240D - Vibration Woes - PeachParts Mercedes-Benz Forum

treiberg · #1 04-28-2010, 12:02 AM

Engine vibration is still present after many attempts to alleviate....

Symptoms: Have some engine vibration at idle and in neutral (but tolerable), much worse when I put it into gear (I shift out of drive while waiting at a light just to avoid the vibration!). Once RPMs are above 1000 or 1200 rpm things smooth out and vibration seems to go away. I see no smoke at idle or under load when driving.

I have done motor mounts, tranny mount, adjusted valves, and rebuilt the injectors with new nozzles and balanced them. By now, I expected a smooth idle!

From reading on the forum, sounds like other things to check are:
-compression (I fear this one because I know the fix is not easy!)
-injection timing
-timing chain stretch
-air getting sucked into fuel system somehow

Any one willing to wager on which of the above it is, or have any other ideas?

(I have a similar post under a topic related to removing motor mount bolts. Thought it fit better under a new thread with a new title since the topic is somewhat different now, sorry for the redundancy.)

layback40 · #2 04-28-2010, 08:13 AM

injection timing/ chain stretch . You should have checked when you did valves !

air would be causing misfire
comp would cause smoke

leathermang · #3 04-28-2010, 08:26 AM

Describe completely what you did when you changed the motor mounts.

markho · #4 04-28-2010, 08:50 AM

damper pin?

Mark DiSilvestro · #5 04-28-2010, 08:53 AM

Does it vibrate, or is it more like a misfire?
In my case, my first 240D (automatic) has a vibration (not a misfire) at idle that new motor-mounts and a valve-adjst didn't cure. Upping the idle speed slightly improved things in neutral. But in drive, the severe vibration continues. The PO's teenager had an accident in this car and some repairs weren't done well. The crossmember under the engine appears slightly bent and the left motor mount doesn't sit square. So I often shift into neutral at long traffic-lights. Otherwise, it drives OK for a $200 car, so I'll put up with the vibration till I sell it.

Happy Motoring, Mark

leathermang · #6 04-28-2010, 09:00 AM

OK, we will add Mark to this question...

Describe Exactly and completely what you did when you replaced the motor mounts.

treiberg · #7 04-28-2010, 09:22 AM

Leathermang, motor mount job was pretty straightforward, bolts underneath were a bit tough, but they finally popped loose, new mounts went in fine. Old mounts were actually in pretty good shape, so didn't surprise me that it didn't make too much difference. Let me know what other details you want. I also did tranny mount. The only mount I did not do was the T-mount. I reallly need to do this also, but for some reason, I can not seem to get it off. The nut on the bolt was missing, so it should pop off once I lift the engine, but it almost feels like someone welded it in place (although don't see a weld). Pounded pretty hard on the mount with a hammer and cannot break it loose. I'll take a pic later and post it.

To describe vibration better...it does not feel like a miss. It is more of a high speed vibration - putting hand on valve cover when running, it just doesn't feel right (I can only compare to my 300SD, which has normal diesel shaking, but not this vibration I feel on the 240D). It almost feels like something is out of timing - the shaking/vibration dampens out at higher RPMs, so I have my idle speed turned up a bit (probably around 900).

Both motor mount and injector nozzzle replacement did seem to help, but core problem is still evident, so I don't want to give up yet.

Mark DiSilvestro · #8 04-28-2010, 09:52 AM

Quote:

Originally Posted by leathermang

OK, we will add Mark to this question...

Describe Exactly and completely what you did when you replaced the motor mounts.

Placed a chunk of 2 x 6 wood and jack under the oil-pan and unbolted the mounts andengine-shock. Also replaced the tranny mount. Pretty straightforward except for the one PITA allen-bolt under the engine-arm!
Noted the left motor mount didn't look very old or bad but had a permanent 'twist' due to the misaligned crossmember.

Happy Motoring, Mark

leathermang · #9 04-28-2010, 10:18 AM

OK...so you are saying.... ...that you did not use the engine mount shop made feeler gauge which the FSM describes how to make and use to make sure your engine is in the correct place?

barry123400 · #10 04-28-2010, 02:56 PM

If your glow plugs are fairly recent a look at the voltage they are producing from cylinder to cylinder might indicate something. The timing by millivolt method thread is pretty extensive but gives you an ideal of how to do it. Basically it is a cylinder to cylinder operational temperature comparison

I will not go back through the posts but I assume you have adjusted your valves. Also look for a stream of bubbles coming through the primary fuel filter.

A fairly static large bubble being present is normal. Last but not least shut off the hose return from the injection pump and post what difference if any presents. If no overall difference at all then the base pressure in the injection pump is too low. If a massive improvement noticed then the actual pressure present needs checked with a gauge.

Mark DiSilvestro · #11 04-28-2010, 07:18 PM

Quote:

Originally Posted by leathermang

OK...so you are saying.... ...that you did not use the engine mount shop made feeler gauge which the FSM describes how to make and use to make sure your engine is in the correct place?

According to my FSM, this 'feeler guage' is only used to adjust the clearance of the front engine 'stop', an engine movement limiter device mounted between the oilpan and front crossmember, which my '82 240D doesn't have.
No adjustment or guage for the front engine mounts is specified.

Happy Motoring, Mark

treiberg · #12 05-03-2010, 07:15 PM

One symptom that is very evident as I am driving the car again today...the vibration is only apparent when the car is in gear (it is an auto) and at a stop. Once I put it in Drive or Neutral, it really has little to no vibration. But stick it into gear, while pushing the brake and car is at a standstill, and the VIBES start! Once you pull away and start driving, things are fine again. Could this mean that the vibration issue is more related to transmission, or does it just mean that the load created by the tranny is causing the engine to shake more, so the core problem is still engine?

10fords · #13 05-03-2010, 10:02 PM

Just a thought- My 81 240D had the same symptoms and it was the exhaust mounting rubbers. One was missing and the other three were stretched beyond their limit. Replaced all four with the good heavy duty ones, not the plain round donuts, and all was smooth again. Good luck- Scott

gatorblue92 · #14 05-04-2010, 03:16 PM

Quote:

Originally Posted by 10fords

Just a thought- My 81 240D had the same symptoms and it was the exhaust mounting rubbers. One was missing and the other three were stretched beyond their limit. Replaced all four with the good heavy duty ones, not the plain round donuts, and all was smooth again. Good luck- Scott

seems odd that exhaust mounts could have such a profound impact on engine vibration...

treiberg · #15 09-06-2010, 12:06 PM

Just an update: I have now checked injection timing (it was fine), checked for timing chain stretch (it was 4 degrees) and have even re-adjusted valves, and still have vibration at idle.

I am beginning to think these just vibrate, although I have a hard time understanding how a buyer would drive one of these off the showroom floor with this anything even close to this vibration, it could not have done this when it was new. I went out and drove a couple of 240D's that were for sale here locally and they both seemed to have very similar vibration at idle.

Only things left to check would be engine compression, exhaust mounts (mentioned above by a member), air getting into fuel lines, and there is one mount (the T mount) that I was not able to replace. Other thought is that maybe there is some issue with the IP pump. I guess I could try to find one on ebay and resell if it doesn't cure issue.

I love this car other than the vibration....this one has no rust, almost perfect body and paint, has been meticulously maintained by previous owners, AC works perfectly, everything else works, etc.