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.

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.

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

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

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.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

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!!

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

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.

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

Problem solved ???

I'll fix the shocks and post results

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

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..

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 )

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 !!

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

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. Now we know that if he had just mounted a pair of engine shocks on her anatomy the problem might have ceased.

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.

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

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. 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.

wow barry, well said!

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!!

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

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