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soothappens 06-20-2010 02:07 PM

300SD Engine oscillation
 
The engine in my 81' 300SD is shaking side to side more of an oscillation.

I got it to stop by turning the Alda 1 turn counter clockwise. It ran smooth but the car used excessive fuel. I turned it back to where it was and the oscillating continues. I have replaced the rack dampener bolt with the gold one and adjusted. It still sways side to side. Turning on the A/C smooths it out also. RPM's are set at 700.

Any suggestions on what to check or search for ?

TchTchr 06-20-2010 02:10 PM

Mine was caused by air getting into fuel lines.

jt20 06-20-2010 02:10 PM

compression would be my first concern.

I assume at this point you've already taken care of injectors?

raising the idle also helps.


Others may say the engine mounts are done.

jimmyL told me that you can jack the engine up by the lower oil pan to check the mounts. Next time the engine is shaking in your driveway.. get a solid piece of wood and try it... pretty easy elimination of that theory.

soothappens 06-21-2010 12:12 AM

Quote:

Originally Posted by jt20 (Post 2490789)
compression would be my first concern.

I assume at this point you've already taken care of injectors?

raising the idle also helps.


Others may say the engine mounts are done.

jimmyL told me that you can jack the engine up by the lower oil pan to check the mounts. Next time the engine is shaking in your driveway.. get a solid piece of wood and try it... pretty easy elimination of that theory.

I haven't checked the compression but The engine seems healthy. No blowby or problems starting. When I bought it the guy threw a small battery in it and it was 40* out started on the first spin without waiting on the glow plugs.
The original engine in the 81' was a new long block with new mounts I used these on the existing engine.
The only thing that is damaged are the engine shock top rubber mounts but after searching it seems they're only for dampening when the engine is shut off.
I also raised the idle but then the transmission shifts into gear hard . It does smooth it out though.

Turning up the alda increases fuel so it could be air in the lines . I guess it could be injectors as well. The only thing that puzzles me is the alda increases fuel over all injectors and this smooths out the engine. If it was one injector would turning the alda really help ?
Tch Tchr where did you find the air coming from?

thanks for the replies guys

Diesel911 06-21-2010 12:35 AM

I would look at the under the hood emission sticker that is on the upper Radiator support and see what your minimum and maximum Idles speed is and would adjust somewhere with in the range until it smooths out some.

Also What do you think is using excessive Fuel and how did you determine that?

Check for the air leak also. It is very cheap and easy just to buy some 5/16 of an inch Fuel hose and change both of the Fuel Inlet Hoses that connect to the Plastic Primary Filter.

What I had to do to get rid of the my vibration/shaking:

Raise the Idle speed within the normal range (this helped some as it was around 700rpm, it likes above 750 rpms).

I bought a new Rack Damper Bolt but it did not help much (like changing the Air Filter Bolts it will not cure vibration caused by other things; will come back to that later)

Rebuilt my Injectors with $16 each brand X Spray Nozzles (This took away most of the shaking)

Doing a Valve Adjustment (took away some more shaking)

Changed Motor and Transmission mounts (took away some more vibration)

Found that I had a small air leak that showed up when the Engine was hot due to hard fuel inlet lines that did not seal even with the clamps tight.

Finally was able to use the Rack Damper Bolt to tune out a little more shake. (that bolt was made to reduce the shake on a new engine; not to compensate for a bunch of worn and out of spec parts

jt20 06-21-2010 01:04 AM

all the things mentioned so far are key items.

one injector off could, indeed, cause the shaking. Raising the fuel / RPM increases the angular momentum (rotational energy) of the crankshaft. This allows for defects in combustion to become less perceptible.

Imagine a perfectly balanced engine running on a stand... it should not bounce around... the shocks / mounts etc.. are really there to absorb finer vibrations... not stop the engine from dancing.

with regards to the poor shifting, perhaps this trans was adjusted before you swapped in this newer engine?

soothappens 06-21-2010 01:45 AM

Quote:

Originally Posted by jt20 (Post 2491240)
all the things mentioned so far are key items.

one injector off could, indeed, cause the shaking. Raising the fuel / RPM increases the angular momentum (rotational energy) of the crankshaft. This allows for defects in combustion to become less perceptible.

Imagine a perfectly balanced engine running on a stand... it should not bounce around... the shocks / mounts etc.. are really there to absorb finer vibrations... not stop the engine from dancing.

with regards to the poor shifting, perhaps this trans was adjusted before you swapped in this newer engine?

That makes sense. So turning the alda basically is like adjusting the idle. Possibly masking a bad injector.
On the transmission it shifts fine but if I raise the Idle to much when you first shift into forward or reverse it really jumps.

The fuel was apparent when I drove my usual rounds.Before turning the alda the gauge barely moved . After it used a 1/4 of a tank for the same trip. Returning it to where I found it the same trip barely moved the gauge again.

I did notice when revving the engine fuel rushes into the plastic primary filter and it fills with bubbles / foam .
I checked all the clamps and they're tight . The fuel rushes in fast and steady you can see the stream so I figured it was just foaming . The hoses all look new. Looks can be deceiving though. As you said 911 a cheap and easy fix. Is this normal or have we found the problem ? On my 240 it fills so slow you barely notice it trickling in so I have no comparison .

barry123400 06-21-2010 09:39 AM

In theory you should see no air leaving the primary plastic filter. As I said in theory it makes sense. Any bubbles traversing the plastic filter should be eliminated first I think.

It is a quantity of air issue I imagine with no established guidelines of how much if any is permitted. The same type of appearance by comparison to the two fourty is a reasonable solution to shoot for. There should be no difference in appearance as you rev either engine to half throttle in that little filter.

Also you are describing a hunting condition in my opinon rather than a roughness? If just a rough constant condition it will be easier to address. A dose of cleaner through the injection pump might be considered after the air is eliminated or reduced. Something might be sticking a little as the rack is govenor controlled I expect if hunting is involved.

Also examine your fuel pump base pressure if you have not already. A temporary test is to clamp off the return line for a minute and see if the hunting ceases. Or roughness declines.

There have been no reports of hunting with low base pressure to my knowledge. I am always on the lookout for abnormal symptoms remember. Rougher idle than is possible is caused by very low base pressure though.

Maybe a combination of low base pressure and some air could be impacting things. I have to wonder if any fuel is overcoming the relief valve and if that fuel shows evidence of air containment in a container with the end of a hose submerged. A few simple things to check that may or may not improve things. They should be checked anyways anytime strange idle conditions exist.

There have not been many posts on hunting posted to my knowlwdge yet still a few if I remember that were not resolved I believe. We did not have as good an undertanding back then though.

Or to look at this generally even if the problem does not go away with getting those things in good shape. The car should actually run better as it hunts.:rolleyes: The only other upside then? You will have a firm grasp of what is not causing the problem.

The only mandatory thing that is indicated is the foaming in the primary filter has to be stopped. Your other car would do it as well if it were normal remember. The fuel supply systems are identical as far as I am aware.

soothappens 06-21-2010 10:36 AM

Quote:

Originally Posted by barry123400 (Post 2491355)
In theory you should see no air leaving the primary plastic filter. As I said in theory it makes sense. Any bubbles traversing the plastic filter should be eliminated first I think.

It is a quantity of air issue I imagine with no established guidelines of how much if any is permitted. The same type of appearance by comparison to the two fourty is a reasonable solution to shoot for. There should be no difference in appearance as you rev either engine to half throttle in that little filter.

Also you are describing a hunting condition in my opinon rather than a roughness? If just a rough constant condition it will be easier to address. A dose of cleaner through the injection pump might be considered after the air is eliminated or reduced. Something might be sticking a little as the rack is govenor controlled I expect if hunting is involved.

Also examine your fuel pump base pressure if you have not already. A temporary test is to clamp off the return line for a minute and see if the hunting ceases. Or roughness declines.

There have been no reports of hunting with low base pressure to my knowledge. I am always on the lookout for abnormal symptoms remember. Rougher idle than is possible is caused by very low base pressure though.

Maybe a combination of low base pressure and some air could be impacting things. I have to wonder if any fuel is overcoming the relief valve and if that fuel shows evidence of air containment in a container with the end of a hose submerged. A few simple things to check that may or may not improve things. They should be checked anyways anytime strange idle conditions exist.

There have not been many posts on hunting posted to my knowlwdge yet still a few if I remember that were not resolved I believe. We did not have as good an undertanding back then though.

Or to look at this generally even if the problem does not go away with getting those things in good shape. The car should actually run better as it hunts.:rolleyes: The only other upside then? You will have a firm grasp of what is not causing the problem.

The only mandatory thing that is indicated is the foaming in the primary filter has to be stopped. Your other car would do it as well if it were normal remember. The fuel supply systems are identical as far as I am aware.

Sometimes a firm grasp on whats not causing it shines a light on what is. ;)

The 240 had algae in the tank bad and the screen was plugged. I have cleaned it but I think the line may still be partially plugged, the reason for the slow flow. The 300 had such a velocity when it entered the plastic filter it amazed me therefore I was considering the bubbles normal.

So I will eliminate the air bubbles and check the relief and fuel pressure. I guess you could call what I'm experiencing hunting, sort of like turning a paint shaker on low. A smooth side to side motion.

I'll check those few items you guys suggested and post results , Thanks.

vstech 06-21-2010 10:55 AM

and VERIFY the motor mounts are good.
I was amazed how smooth the motor in my 300 became after I changed the mounts that looked fine, but were not.

TchTchr 06-21-2010 11:53 AM

I had air coming in from the secondary mount somehow. A few new crush washers and o-rings didn't help so I got a mount from a friend and the problem got solved. New motor mounts helped a bunch too. The old ones were completely shot.

barry123400 06-21-2010 05:03 PM

Quote:

Originally Posted by soothappens (Post 2491388)
Sometimes a firm grasp on whats not causing it shines a light on what is. ;)

The 240 had algae in the tank bad and the screen was plugged. I have cleaned it but I think the line may still be partially plugged, the reason for the slow flow. The 300 had such a velocity when it entered the plastic filter it amazed me therefore I was considering the bubbles normal.

So I will eliminate the air bubbles and check the relief and fuel pressure. I guess you could call what I'm experiencing hunting, sort of like turning a paint shaker on low. A smooth side to side motion.

I'll check those few items you guys suggested and post results , Thanks.

My misteak amoungst many. Hunting is an almost constant varience in revolutions. The engine seems to always be hunting for one spot but will not maintain it.

At idle is when that weird uncommon condition is usually observed. I guess with a bracket on one of these engines if shaking enough would mix paint.:rolleyes:

soothappens 06-22-2010 01:02 AM

Alright I changed the Two lines to and from the primary filter. They where hard and cracking. You had to really bend them to see it. I'm still getting the air bubbles. Even at idle you see tiny bubbles if you look closely.

I guess the only other place would be the tank line from the filter to the steel supply line . The clamps where tight on these lines as well but probably cracking.

I made a test fitting from a spare filter return line the three way one on top.
I plugged off one line hooked the gauge to the small barb and routed the clear line from the secondary filter outlet to the injection pump inlet.
This gave me a true reading of what the injection pump was seeing. The gauge was bouncing from 3 psi to 8 psi constantly. revving the engine above 2000 rpm resulted in the gauge quivering around 15 psi.

I pulled the ball and spring from the return side and found both a bluish purple . They looked as if they seen bad heat. I replaced the return check with one that I had stretched the spring to 27mm. The gauge stayed rock steady at 19 psi.
This improved drive ability and the engine was quieter at high RPM's as well.

Its still shaking side to side though. I was backwards on my original post.
At Idle 750rpm its happy and smooth when I turn on the A/C is when it sways side to side.

It was dark so tomorrow I do the motor mount test and see if I can pin point the air leak

Thanks again guys your posts are helping.

barry123400 06-22-2010 09:55 AM

How about feeding the engine from a small container of fuel first? If normal in primary fuel filter and idle is much improved with that then go backwards. You could reverse the pickup and return lines as well I suppose. You need 1/2 tank or so of fuel to enable this I understand.

I am a little leary of doing that as any gunk built up over time in the return line might migrate through the injection pump. Inserting a small primary filter and piece of hose in the return line would protect the injection pump though I suppose.

You do not want to land up doing more under there than required. Unless it is benificial overall like getting the base pressure of the injection pump corrected as you did.

It is becoming strange that so much improvement in the system is available just by correcting the base fuel supply pressure properly with a gauge as you have done.Yet so many still ignore it. After the idle problem is solved you will find that even if it took a fault to get it done it was usually worth having the fault to enable it happening.

Or after you correct the first one for base pressure you will at least check any subsequent or existing cars of this type. My suspicion about the number one rod bearing remains unproven but get the base pressure in the proper area as well on that two forty if it is not. Anyway you look at it the additional power on the two forty is wanted if available usually.

As people have mentioned it could be soft motor mounts but just as easily an imbalance of power pulses in the engine.

I have recently added the ideal of adding the check of the delivery valves test for leakage to the list of probabilities to be examined if what we currently consider normal things do not restore good idle. This at this point is somewhat of a shot in the dark so I will be looking for candidates for this issue as time goes forward. Your car is not there yet.

Unfortunatly for you since we tend to think a little along simular lines as I mentioned awhile ago. Once you clear the fuel supply system as a cause. Time to read the milli volt method to locate the imbalance if not the engine mounts. I guess it would be wise to check the valve clearances first.

On the otherhand if it is just an injecting fuel problem the milli volt thing will locate it quickly enough. I have almost concluded that the occassional bubble up through the primary filter may not be signifigant enough. I just do not know at what point the amount of air becomes a real issue. In theory again there should be none.

The appearance of foaming in the primary filter may allow a lot of very small bubbles up the line that are not visable as basically the fuel may be entraining air . It may become interesting to get to the botttom of your problem. Unfortunatly for us observers there is still an excellent chance that just air in the fuel might be involved.

soothappens 06-22-2010 10:18 AM

Quote:

Originally Posted by barry123400 (Post 2492010)
How about feeding the engine from a small container of fuel first? If normal in primary fuel filter and idle is much improved with that then go backwards. You could reverse the pickup and return lines as well I suppose. You need 1/2 tank or so of fuel to enable this I understand.

I am a little leary of doing that as any gunk built up over time in the return line might migrate through the injection pump. Inserting a small primary filter and piece of hose in the return line would protect the injection pump though I suppose.

You do not want to land up doing more under there than required. Unless it is benificial overall like getting the base pressure of the injection pump corrected as you did.

It is becoming strange that so much improvement in the system is available just by correcting the base fuel supply pressure properly with a gauge as you have done.Yet so many still ignore it. After the idle problem is solved you will find that even if it took a fault to get it done it was usually worth having the fault to enable it happening.

Or after you correct the first one for base pressure you will at least check any subsequent or existing cars of this type. My suspicion about the number one rod bearing remains unproven but get the base pressure in the proper area as well on that two forty if it is not. Anyway you look at it the additional power on the two forty is wanted if available usually.

As people have mentioned it could be soft motor mounts but just as easily an imbalance of power pulses in the engine.

I have recently added the ideal of adding the check of the delivery valves test for leakage to the list of probabilities to be examined if what we currently consider normal things do not restore good idle. This at this point is somewhat of a shot in the dark so I will be looking for candidates for this issue as time goes forward. Your car is not there yet.

Unfortunatly for you since we tend to think a little along simular lines as I mentioned awhile ago. Once you clear the fuel supply system as a cause. Time to read the milli volt method to locate the imbalance if not the engine mounts. I guess it would be wise to check the valve clearances first.

On the otherhand if it is just an injecting fuel problem the milli volt thing will locate it quickly enough. I have almost concluded that the occassional bubble up through the primary filter may not be signifigant enough. I just do not know at what point the amount of air becomes a real issue. In theory again there should be none.

The appearance of foaming in the primary filter may allow a lot of very small bubbles up the line that are not visable as basically the fuel may be entraining air . It may become interesting to get to the botttom of your problem. Unfortunatly for us observers there is still an excellent chance that just air in the fuel might be involved.

That's a good idea on the aux fuel source. The simple things sometimes elude me in my quest to reinvent the wheel. :rolleyes:

I did the valves two weeks ago all were tight. I could have sworn I did the check valve as well , but it turned out I did it on the engine that came out. That's the valve I'm using now.

I also did the millivolt method and all were dead on. Reconfirmed that with a thermocouple on each glow plug and injector. They were all in the same temp range.

After sleeping on it I wonder if the A/C is just bringing the Idle down to low. These older cars don't have any provisions to raise the idle when the A/C kicks on do they ? Other than the governor ?

I'll try an aux source of fuel tonight. thanks Barry

barry123400 06-22-2010 10:18 AM

Well I missed the idle is smooth at 750rpm indicated and roughens up when the air compressor is engaged. Some air incoming may still enable that. It has to be eliminated as a posssible cause anyways.

I am starting to think that next is a general check of chain stretch, primary pump timing and valve adjustment. Thats with all possibility of air being a factor gone. If all that checks out then this car is a really good candidate for examination or a scan with the milli volt method in my opinion. This in my opinion is also the best dynamic check of the fuel injectors condition available to us at present. In a nutshell if an engine deviates from equal power strokes as overall designed or the designed function is upset by common wear of timing chains etc. It does not respond well in an equal cylinder to cylinder fashion as load is applied. Even if it is just the load of an air compressor.

I also think marginal motor mounts could contribute as the compressor is a loading factor for the engine.

barry123400 06-22-2010 11:23 AM

Well being a slow thinker and observer I missed your last post on page one. I should have remembered the tests you applied to this engine some time ago. You are one of the few. I only can hope others will catch on.

The logic basically is otherwise when these cars where delivered new the shake would have been a warranty issue complaint. So it is still not normal in my opinion.

I am pretty sure the manufacturers idle design was high enough to compensate for the load of the compressor when applied. Now if the air system was converted to 134 the compressor load is much higher than with r12 I believe. Although living so far north air conditioning is not common knowledge to most of us.

When living in he south dealing with air conditioning is like puting air in your tires I imagine. So maybe someone with a lot more knowledge could comment. Anyways glad to hear your engine is fairly well balanced powerstroke wise. I still do not like your description of the fuel in the primary filter.

If the engine runs better with the external fuel source fine.If not the final check valve in the lift pump may be suspect. The same general appearance in the primary filter would still be there. It could very easily look like foaming I suspect. Usually you would see a surging back and forth in the primary filter as well I would imagine. Maybe not. This is another unproven observation.

I almost feel lost with all my unproven suspicions. Some with time seem to eventually get proven and that makes me feel a little better anyways. It takes the effort of people such as yourself to let us plunge forward.

The delivery valve test for example is getting off to a very weak start. Based on them only being check valves. Check valves being notorious in my experience for developing problems over time it seemed rational to me and still does. You of course have no symptoms that they are an issue with your car.

You are already well ahead of the average at locating the issue. There is no shotgun approach being used by you. What was originally offensive to me was that there seemed almost no systematic approach possible at one time or in use not that many years ago. Or what was available was too limited.

This was okay if you were a working mechanic pehaps as the intuition from experience factor covered it somewhat. Then there were too many guys like myself on site that have to struggle to find time on occassion to work on their cars only in a sporatic fashion. The interaction on this site anoungst many members is enableing this to change.

soothappens 06-22-2010 11:24 PM

I got home late and didn't get to check the air in fuel issue. The wife drove it all day and said there was a vast improvement overall. It still swayed side to side but she said it drove much better.

I will be making a gauge port leading into the secondary filter as I couldn't believe how far off the fuel pressure was. This will also let you know when your filter becomes obstructed.
All my tests where done on the port leading out of the secondary filter before the injection pump not a good place due to the possibility of trash entering the pump. The line I used was cleaned and re cleaned before attempting it though. I wanted a true reading without the filters.

The A/C is R12 and when I did the valves I checked the chain stretch it was right on the money. On the timing The injection pump has the chisel mark across it and the block and its right on. I left well enough alone on that one.

The fuel pump check concerned me as well when you rev it you couldn't tell which way the bubbles where entering. I did move the filter around and it is coming from the tank side. (real small bubbles at idle)

Troubleshooting is the hardest part and the brainstorming we do on this forum helps a bunch (take the aux fuel source as an example ) Don't give up on your suspicions some just take a little longer to prove.

Once again I appreciate the input :thumbsup:

whunter 06-22-2010 11:50 PM

Disagree
 
Quote:

Originally Posted by soothappens (Post 2491185)
The only thing that is damaged are the engine shock top rubber mounts but after searching it seems they're only for dampening when the engine is shut off.

The engine shocks are for shake/rock at idle and lower RPM.

Engine Shock Mount, Upper (2 Per Car)
MB#116 241 33 13

Engine Shock Mounting Kit, includs upper mount, two bushings, two washers, two nuts, and two bolts (2 Per Car)
MB# 116 240 00 17




Have a great day.

soothappens 06-23-2010 12:14 AM

Quote:

Originally Posted by whunter (Post 2492583)
The engine shocks are for shake/rock at idle and lower RPM.

Engine Shock Mount, Upper (2 Per Car)
MB#116 241 33 13

Engine Shock Mounting Kit, includs upper mount, two bushings, two washers, two nuts, and two bolts (2 Per Car)
MB# 116 240 00 17




Have a great day.

Thanks !

Most of the threads I read contributed them to shut down. Some even said they were missing or never installed since they had the cars. (endless searching on my 240 and 300SD )

Are these dealer only Items ?

Found them on fastlane Thanks again!!

barry123400 06-23-2010 01:00 AM

Hunters suggestion makes sense as well come to think of it. Mercedes may have had an issue with designing motor mounts.

Hard enough to stabilise the engine mounting at low rpms and the car would have had too much vibration transfered.

Soft enough mounts to minumise the issue may have had unwanted effects at low rpms. They would not have added the engine shocks unless it was a problem they could not work around otherwise. They were an expense that is usually not required or used on most engines.

Like all shocks systems they wear out with use I imagine. If the new parts reduce your problem substantually. It will update what to other posters with simular complaints as well should check out. Once the common things are checked properly that is.

I too like an engine that sits pretty still and sounds good at idle. Or at least as good as possible.

soothappens 06-23-2010 11:11 AM

After showing the wife the price of the kits she no longer thinks the rocking is so bad !!

Problem solved ??? :D

I'll fix the shocks and post results ;)

barry123400 06-23-2010 04:27 PM

Quote:

Originally Posted by soothappens (Post 2492808)
After showing the wife the price of the kits she no longer thinks the rocking is so bad !!

Problem solved ??? :D

I'll fix the shocks and post results ;)

Hope that does it. Still if the primary filter does not have a very stationary static bubble at idle or air is moving through I would find the cause and eliminate that anyways. The alternate fuel supply source should tell you if it is an issue.

The overall problem could easily be a combination of two factors rather than just one. Any air getting into the injection lines in a random fashion is going to unbalance the engine a little. Enough to be noticeable with only the compressor load is the unknown question.

Anyways post details of whatever you do. Normally the base idle is smoother with the base pressure corrected or at least quieter. This is a clue perhaps the air might still be a problem if idle quality without the compressor load did not smooth out more than it was.

I am just saying it may or may not be just the shock mounts..:D

soothappens 06-23-2010 11:44 PM

Well for about twenty cents worth of parts ( two 1/2 inch flat washers ) and an hours worth of work I fabricated 2 indestructible upper shock mounts.

I welded the flat washers into the top mount about 3/8 from the bottom and then used a spare set of bottom mount bushings to secure the shock into the mount. tightening the nut squeezed the bushings tight into the mount.
This replicated the factory mount but without the chance of the rubber pulling through. (thanks to a frugal wife ) :D

I reinstalled them on the car and the engine is smooth as glass. Wow what a car!!
Yes the shocks do make a difference on the 617 and not just for shut down.

As for the air Barry I'm going to try the aux fuel supply and I will post results. The fuel pressure definitely improved the performance . To think If I hadn't gone the round about way on this problem I most likely would be replacing the injection pump before long.

A very big thank you to all !!

barry123400 06-24-2010 11:43 AM

So for any light loading causing engine motion to occur will mean posters will have to examine their engine shocks from now on. Just another item on the list to keep in the back of our minds. In a way it is good you had the problem so we now know that. . At the same time not enjoyable for you perhaps.

Injection pump replacement with your nice even milli volt readings was unlikely to occur. Or at least I would have argued against it. I have come to the conclusion some time ago there has to be real indicators it is required. Sure element to element timing might be off a shade with age. But for the engine to produce effects that are really percievable to us the burn temperature has to be different from cylinder to cylinder.

Hunter of course was right about the engine shocks function. Just strange that knowledge was not really common on this site before.

I liked your creative self fix approach as well. Perhaps an improvement on the original mount design as well. The worn out or broken shock mounts indicate on your car those shocks were functioning and a real requirement. Call it hindsight. No reason others cannot avail themselves of your fix. I do not think you would mind.

Since some 123 engines have them and some apparently do not makes me wonder what they were thinking at the factory. You would think they would all have had them.

There is still a chance you might get even further improvement when you get the fuel flow through the primary filter looking normal. I really believe there is a normal for that at least.

All the reflected pressure waves in the fuel supply system could produce interesting side effects. Mercedes or the pump manufacturer have designed a couple of things into that system that have me wondering.

The second check valve in the lift pump for example. The fuel filters would dampen the reflected waves somewhat from the injection pump I would think. Maybe not much if the fuel filters are clean.

There are a lot of very short duration spike pulses being generated in the base of the injection pump. could they affect the lift pump if the secondary valve in the pump was defective?

I think inertia of the lift pumps piston might stop any action if they get through. On the otherhand perhaps those spikes combined are generating something that might cause some effect.. They also may be completly benign.

Foaming or surging in the primary filter may be an indication the secondary valve in the lift pump is staying open. The effect might also be more prounounced with the low relief valve opening pressure you had. The presure differrential being larger.

The lower the fuel pressure in the base of the injection pump the more the pressure will try to surge back and forth. Since you adjusted the base pressure I expect you should see less or no foaming. The only indication it might still be there to some extent might be an unstable bubble. The actual air going through is another issue that should not be there at idle.

Where is all this going? Hopefully at some point an eureka will occur that will let us add a modification that improves something that the original designers missed in development. Not too high a chance of it but I for one am looking over time for any possibility of it. The system is basically simple yet there are still things to learn about it I believe.

Do you remember the post where the guys wife complained the vibration was so bad it was shaking her mamory glands at idle? There were a lot of requests for pictures.:rolleyes: Now we know that if he had just mounted a pair of engine shocks on her anatomy the problem might have ceased.:D

soothappens 06-25-2010 01:46 AM

The wife drove the car all day. She said it ran much better no shaking and real quiet. (so quiet she found other problems / noises ) :(

I enjoy working on these cars just don't have as much experience as most on this forum.
Any little I can give back is satisfying . The plus is actually fixing what you where after.

On the engine shocks are they just on the 617 ? My 616 doesn't even have a place for them but it never had the side to side problem even running poorly.

The top mounts where soaked in oil so it deteriorated the rubber letting it pop out of the metal mount.
One side looked like it was still attached but when removed it was in two pieces.

The rubber on the shock mounts is a very soft compound . I'm guessing this is to prevent vibrations.
The only improvement I would make is to use poly bushings instead.
The ones on a Chevy front sway bar mount look like they would probably work.

Time will only tell how this fix holds up.

Diesel 911 has been kind enough to put directions on posting pics but I just don't get it. If my son can help me I will post pics of the top mount repair.

I still have the bubbles in the primary . Increasing the pressure helped drive ability but had no effect on the air . This weekend I will troubleshoot it some more.



And yes my wife's boobs are no longer bouncing. How could I forget that one. :D :D

barry123400 06-25-2010 10:09 AM

You would think the four would automatically be more prone to requiring the shocks. Might just be the harmonics of the five cylinder occur in a more critical area. The five cylinder configuaration has never been a popular industy standard except for a few makes and even then only of a sporatic nature I think.

Come to think of it maybe your married to one of my wifes relatives. :D My wife can detect the slightest thing wrong with a car. She should have been a mechanic dealing in obscure faults.

Of course I get notified if she detects anything. Over time I have learnt it is better to not put it off too long getting to it. I just love it when she detects a squeek.

Well one has to be fair. She always has been excellent in other ways. This of course has to be qualified a little as she still posseses the common traits of her specis. I think they all do.

She is very smart as well. I often wonder why she picked me. Perhaps I seemed easy to torture. Or she was just bottom fishing. Who can say.

All I know it works well in comparison to a lot of situations I see. Now that the sand is getting ever lower in the hourglass I really can appreciate what we had and still have.

She even tries unsuccesfully to get me to limit other activities and commitments so I can get to things like working on my own cars. She wants to see me get to the things in life she knows I enjoy doing. Basically stating that I have already done more than my fair share out there.

One of the few outlets I make time for is this site. The amount you can learn and insite you can gain here is amazing. Idealy wished we as members lived closer together in the same geographical area.

vstech 06-25-2010 10:20 AM

wow barry, well said!

soothappens 06-27-2010 05:05 PM

Quote:

Originally Posted by barry123400 (Post 2494071)
You would think the four would automatically be more prone to requiring the shocks. Might just be the harmonics of the five cylinder occur in a more critical area. The five cylinder configuaration has never been a popular industy standard except for a few makes and even then only of a sporatic nature I think.

Come to think of it maybe your married to one of my wifes relatives. :D My wife can detect the slightest thing wrong with a car. She should have been a mechanic dealing in obscure faults.

Of course I get notified if she detects anything. Over time I have learnt it is better to not put it off too long getting to it. I just love it when she detects a squeek.

Well one has to be fair. She always has been excellent in other ways. This of course has to be qualified a little as she still posseses the common traits of her specis. I think they all do.

She is very smart as well. I often wonder why she picked me. Perhaps I seemed easy to torture. Or she was just bottom fishing. Who can say.

All I know it works well in comparison to a lot of situations I see. Now that the sand is getting ever lower in the hourglass I really can appreciate what we had and still have.

She even tries unsuccesfully to get me to limit other activities and commitments so I can get to things like working on my own cars. She wants to see me get to the things in life she knows I enjoy doing. Basically stating that I have already done more than my fair share out there.

One of the few outlets I make time for is this site. The amount you can learn and insite you can gain here is amazing. Idealy wished we as members lived closer together in the same geographical area.

You where right again. After Google brought up any site with engine shake , roll etc. and lots of reading it appears that the 617 was prone to this problem due to the harmonics , and pulsations at idle. At least thats what I interpreted it as at 2:00 am. One site said it was a mystery to Mercedes as well The reason behind the new rack dampener bolt. Some will shake and some don't.

It said its worse when the engine is warm at idle due to the timing mechanism in the pumps becoming looser and wearing with age. Acceleration takes up the slack.
Recommended repair is overhaul or change the pump.

Not much was mentioned regarding the shocks though. This in my opinion pretty much eliminated the problem. There is a ever so slight rock barely noticeable but maybe I'm getting spoiled at this point.

I did the Aux fuel supply test. I ran a diesel purge on it 2 birds with one stone. The bubbles where still there leading me to believe its in the fuel pump. Either the primer pump or the check valve. I have a spare so that should be an easy test. Diesel 911 has some good posts about that. Back to the search.

The engine runs 110 % better quiet on the highway and you can feel the governor doing its job.
The wife is happy so problem solved.

Sounds like you have a good thing going there it makes for a happy life. I Don't worry to much about the sand as some have outlasted the wood that the hourglass is held together with ! ;)

Thanks again for the help. As for the distance were only a click away!! :D

clintard 06-27-2010 08:43 PM

Pics to go along with this thread would be really awesome. Im having the same problem you are with the rocking. Id love to see how you rigged your engine shocks so i can do the same and see what happens with mine.

How do you check to make sure your fuel pressure is correct? Id like to do this but i cant make sense of how to do it from reading this thread. I have an electric fuel pump feeding my engine, but it makes no difference in running when you pull the fuse to it. Its part of an aftermarket biofuel system.

Also, what is the millivolts test?

My friend just bought a total beater 300D rust bucket that does exactly the same thing. (picked it up the other day for 500$, rust holes all over it)

Both cars make a thuddy (thud thud thud thud) sound from the exaust and a steady side to side rock of the engine. On both cars this only happens after the car is fully warmed up and driven a while and only at idle. Give either car a touch of throttle and it runs smooth. Adjusting RD bolt seems to have no effect on either car (both cars have old style)

We think the rocking and thud thud sound from the exaust indicates either low compression on a cylinder or two, OR that our valves are way out of adjustment and are not seating correctly when idling. Neither car has any record of the last adjustment. PO of my car said hes never done it and he had the car for 3 years and unknown miles.

I dont have the extra cash for the valve adjusting wrenches right now and he says he cant and wont justify spending 80$ on a set of wrenches for a 500$ car. I will buy the wrenches soon so we can eliminate this as a possible cause or a cure.

Today we both did diesel purge. His IP was so dirty that the clear liquid turned dark BLACK. Definitely did some cleaning and plugged the filter. Mine didnt change colors whatsoever and didnt plug the filter either.

We also cracked the pressure lines going to each injector while the cars were both rocking and every single line cracked made a very noticeable change in engine note. Does this eliminate injectors causing the rocking?

EDIT: My car is an 83 300D and his is an 82 300D

I really appreciate all of the help and support given here. Thank you

soothappens 06-28-2010 12:57 AM

Quote:

Originally Posted by clintard (Post 2495227)
Pics to go along with this thread would be really awesome. Im having the same problem you are with the rocking. Id love to see how you rigged your engine shocks so i can do the same and see what happens with mine.

How do you check to make sure your fuel pressure is correct? Id like to do this but i cant make sense of how to do it from reading this thread. I have an electric fuel pump feeding my engine, but it makes no difference in running when you pull the fuse to it. Its part of an aftermarket biofuel system.

Also, what is the millivolts test?

My friend just bought a total beater 300D rust bucket that does exactly the same thing. (picked it up the other day for 500$, rust holes all over it)

Both cars make a thuddy (thud thud thud thud) sound from the exaust and a steady side to side rock of the engine. On both cars this only happens after the car is fully warmed up and driven a while and only at idle. Give either car a touch of throttle and it runs smooth. Adjusting RD bolt seems to have no effect on either car (both cars have old style)

We think the rocking and thud thud sound from the exaust indicates either low compression on a cylinder or two, OR that our valves are way out of adjustment and are not seating correctly when idling. Neither car has any record of the last adjustment. PO of my car said hes never done it and he had the car for 3 years and unknown miles.

I dont have the extra cash for the valve adjusting wrenches right now and he says he cant and wont justify spending 80$ on a set of wrenches for a 500$ car. I will buy the wrenches soon so we can eliminate this as a possible cause or a cure.

Today we both did diesel purge. His IP was so dirty that the clear liquid turned dark BLACK. Definitely did some cleaning and plugged the filter. Mine didnt change colors whatsoever and didnt plug the filter either.

We also cracked the pressure lines going to each injector while the cars were both rocking and every single line cracked made a very noticeable change in engine note. Does this eliminate injectors causing the rocking?

EDIT: My car is an 83 300D and his is an 82 300D

I really appreciate all of the help and support given here. Thank you

Welcome to the forum. One of the most informative I've found on any Mercedes you might have.

First do your maintenance . Filters and valve adjustment ' as for the wrench's I use regular open ends . This is a little trickier probably takes a little longer as well but if you hold your tongue the right way...........;)

On the pictures I'm working on that. I resemble a cave man chiseling on a rock when it comes to the computer. My sons the guru still waiting on his help. :wallbash:

As for the shock mounts the top ones where the damaged part . Thinking about it you could easily put a 1/4 " fender washer on the top and bottom of this mount and reinstall the shock to see if it helps. This would only be used for testing because your making a solid steel mount the vibrations would run throughout the car. Pull the mount and you'll get the idea. It sure helped in my case.

The milivolt thread is a long one but a good read. Here's the link:

http://www.peachparts.com/shopforum/diesel-discussion/152389-setting-pump-primary-timing-milli-volt-method.html?highlight=milivolt

The fuel pressure thread is another long one but packed with info as well
Here's that link :

http://www.peachparts.com/shopforum/diesel-discussion/234609-fuel-pressure-relief-valve-adjustment.html?highlight=fuel+pressure

Get a cup of coffee and enjoy the reading !! :D

clintard 06-28-2010 03:43 PM

Thank you. I think the millivolt thing is over my head so im gonna stay away from that for now. I just read the entire relief valve thread. Im going to go see if i have the serviceable or non serviceable bolt. If i can access the spring i will try and stretch it and see if that helps.

Will be ordering a couple valve cover gaskets and hopefully doing valve adjustment soon. Ive never done it before so it will be a task.

barry123400 06-28-2010 03:56 PM

The condition of the body metal is not a good indicator of the engine in my experience. I have seen really good engines in rusted out bodies. When I say really good I mean far above average.

If I were you I might start by checking the motor mounts and engine shock mounts if you wish. Valve adjustment is a maintenance required item every 15k. Although every valve clearance check will not always mean all of them need adjustment. They should still be checked.

On an older unmaintained example there are so many things to check out in the fuel supply that you should get a 10.00 30 pound gauge from a place like harbour freight. Make sure it is a liquid dampened one. I recommend a permanent installation unless you have to use it on multipal cars.

Stretching the spring only works if you have the pressure available to use the increased relief valve setting. The gauge will tell you if your fuel filters are clear enough, the lift pump producing properly, the screen in the tank clean, fuel lines not obstructed etc. Also the gauge lets you set the pressure where it should be. You want 19 pounds operational base pressure with overflow capabilities still existing from the relief valve.

To be fair the milli volt thing is reserved for the times when everything obvious has been looked at. Then it can help locate problems rather than just spending money by shotgunning. That can be a very painful methology and you can still have the problem remaining afterwards. Many have experienced this. I can easily live without the financial pain involved.

clintard 06-28-2010 04:43 PM

I forgot to mention that on both cars when we ran low enough on the diesel purge we filled the makeshift mini gas tank (biggest mason jar they make) with clean diesel fuel and then went and drove. The engine still shook/rocked on both cars running off a mason jar full of diesel after a 5 mile run driving like maniacs.

I think ive eliminated air bubbles, tank strainer, fuel lines etc by doing this.

If i clamp off the return hoses on both cars when they are doing the shaking/rocking after warm and they continue to do so, would this eliminate the possibility that the cause is low fuel pressure at idle?

barry123400 06-28-2010 05:13 PM

Proper base fuel pressure does make the idle sound smoother for many reasons. You are describing major shaking though. Fuel presssure would not differentiate between hot and cold engines I suspect.

It will do no harm to close the return off though and if the engine runs a little different it means the lift pump filters etc are flowing well enough to increase the pressure on demand. Plus the relief valve was working with an unknown release pressure before the clamp off.

Now if you disconnect the fuel relief line you should get some fuel flow out the line while running. Also submerging that line in a jar of fluid and watching the level increase with no bubbles at least totally clears you of air being present.

Be sure to do that with the engine really warm though as you could be getting air when warm only.

At this time it could be one item or a combination of items.

Back up and start with the valve adjustment. When you come down to hot idle with poorly seating valves you might be partially loosing a cylinder or two. You know your valve clearances are way overdue for a check anyways. This is not unusual in itself.

The exhaust valves for example would have expanded with the heat of the run making any slightly tight valves cold now possibly slightly open hot. In your case you have to cover the basics first. It would only take one exhaust valve having no clearance cold to do this remember. The clearances on the valves decrease with usage and wear over time.

clintard 06-29-2010 01:12 PM

Barry, ive gone through a lot of your past posts in different threads and read them. You know your stuff. Are you an engineer? Thanks for your help, you are appreciated.

I will do the valve adjustment as soon as i can and re check them after a few hundred miles.

I will also take before and after videos of both cars cold and hot so if it helps our problem other noobies can see. If you would like to see anything else in the videos i can do that too. Dont hesitate to ask.

Last night we took the relief valve out of my friends car, measured the spring at 21mm and stretched it to 27mm. Put it back in and we havnt noticed a difference. I have yet to check mine as id like to see what my base pressure is with a gauge before i stretch it.

MBeige 06-29-2010 04:16 PM

Quote:

Originally Posted by soothappens (Post 2493358)
Well for about twenty cents worth of parts ( two 1/2 inch flat washers ) and an hours worth of work I fabricated 2 indestructible upper shock mounts.

I welded the flat washers into the top mount about 3/8 from the bottom and then used a spare set of bottom mount bushings to secure the shock into the mount. tightening the nut squeezed the bushings tight into the mount.
This replicated the factory mount but without the chance of the rubber pulling through. (thanks to a frugal wife ) :D

I reinstalled them on the car and the engine is smooth as glass. Wow what a car!!
Yes the shocks do make a difference on the 617 and not just for shut down.

As for the air Barry I'm going to try the aux fuel supply and I will post results. The fuel pressure definitely improved the performance . To think If I hadn't gone the round about way on this problem I most likely would be replacing the injection pump before long.

A very big thank you to all !!

That's it, I'm ordering these next :D

barry123400 06-29-2010 06:55 PM

Quote:

Originally Posted by clintard (Post 2496301)
Barry, ive gone through a lot of your past posts in different threads and read them. You know your stuff. Are you an engineer? Thanks for your help, you are appreciated.

I will do the valve adjustment as soon as i can and re check them after a few hundred miles.

I will also take before and after videos of both cars cold and hot so if it helps our problem other noobies can see. If you would like to see anything else in the videos i can do that too. Dont hesitate to ask.

Last night we took the relief valve out of my friends car, measured the spring at 21mm and stretched it to 27mm. Put it back in and we havnt noticed a difference. I have yet to check mine as id like to see what my base pressure is with a gauge before i stretch it.

Now if you clamp or close the return line off on that car and there is no difference. I expect there will be none by the way. Your operational fuel presssure is pretty low. All the clamp off in your case is doing is verification the relief valve is not open . I still believe this is not your primary problem. Just that it deserves to be rectified for the car to run well. Add it to the list to deal with later.

As for me? Of no importance. Just an average guy with many interests that is always too busy. I would feel more comforatable on this site if I were a working mechanic. Since I am not I really try to suggest what my approaches would be in a simular situation as a poster. Many other members do the same exact thing remember. We all have something to contribute in my opinion.

Also I am an occassional amateur mechanic I suppose with not enough time to get my hands dirty usually. Plus I have always had an inquisitive mind.

Remember I will be and can be wrong on things as well.

I also like probing into areas not well covered or understood in general by the majority of us. There will be failures yet from the probes knowledge will grow for all of us to use if we wish. The posters really help with their experiences. Remember it is far from one sided. It takes a lot of effort and positive results by many before any general new approaches are accepted.

For example if you purchase a gauge to check the fuel pressure. You are still amongst the few as this to me important usage has not solidified yet. Once you correct the problem and post others will be tempted to try it or at least seriously consider it. You have to prove concepts in spades before people will change.

With the support of this site and your participation you and your friend will get your cars repaired. That is one of the primary reasons you are here and this site does cater to it. You in theory cannot bond with an inanimate object yet with old diesel cars it can and does happen.

soothappens 06-30-2010 02:44 AM

I figured out the picture thing.

I'll fabricate another top mount and take pictures to post this time. Time being tight please bear with me.

clintard 06-30-2010 12:34 PM

Quote:

Originally Posted by soothappens (Post 2496690)
I figured out the picture thing.

I'll fabricate another top mount and take pictures to post this time. Time being tight please bear with me.

Greatly appreciated! I did a visual check of my engine shocks and everything LOOKS fine, even with engine running.

4thesporty 06-30-2010 01:52 PM

Quote:

Originally Posted by soothappens (Post 2496690)
I figured out the picture thing.

I'll fabricate another top mount and take pictures to post this time. Time being tight please bear with me.


I really look forward to seeing this pic. My drivers side top mount is completely torn through and I have really been putting off buying one at >$90 :eek:

Thanks for taking the time to do this.


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