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 ?

__________________


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

Mine was caused by air getting into fuel lines.

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Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke

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.

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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

__________________


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

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

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84 300D, 82 Volvo 244Gl Diesel

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?

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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 .

__________________


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

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. 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.

__________________


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

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.

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.

__________________
Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke

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.

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.

__________________


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

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.

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

__________________


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