Vibration when stopped in drive
 

I am new to the forum...

I have a big vibration problem with my 82' 300SD. It is only when
the transmission is in drive and foot on the brake. If I put into
reverse, it seems perfect. This problem has been driving me crazy
for some time now..

Any advice or ideas would be very much appreciated!

Thanks, Dan

Here is what I have done so far

1) new motor mounts
2) new engine shocks and shock bushings (rubber)
3) new trans mount (I may have not replaced this on this
car.. I could be mixed up with my old
240d)
4) new filters
5) 2 cans of LB diesel 100% purge (primed the system and connected
supply and return lines to a can)
6) New upgraded gold colored rack damper bolt/spring


I plan to adjust the valves, check for timing chain stretch and check
compression next week, but since everything is OK in reverse, it
makes me think the problem is somewhere else..

Adjust your valves before you do anything else, then drive the car like you stole it. That may solve your problem - you'd be surprised by the difference a valve adjustment can make.

i just put a new flex downpipe on my 300d and seems that it is so close to the tranny that it will vibrate against it when i'm at a stop with my foot on the brake. it's very annoying, to the point of me putting the car in park so as not to hear it. i am pretty sure i put the pipe on correctly, but am going to take it to the muffler shop at the end of the street just to be sure. perhaps they can pry it away from the tranny...is your vibration a metal slapping sound such as i'd describe mine to be? or is it more like an engine shaking vibration situation?

vibration
 

I think it is more shaking... If I watch the
oilpan, there seems to be no movement, but
the air filter housing seems to shake pretty
good, but only in drive.. Not reverse..

I'll do the valves and then adjust the rack damper
and keep my fingers crossed...

Looks like the exhaust hanger on the down pipe
has rubber bushings.. I'll check them out as well.
This one has been a pain... Car seems to run perfect
otherwise.. Zero smoke and 28 mpg..

Thanks!

Dan

how bout the air cleaner mount/bushings. i went to replace my bushings as it was shaking a lot and making a racket, and found out that 2 of the 3 mount arms were broken:eek::eek::eek:

air cleaner mounts
 

My air filter housing did have 2 broken rubber mounts as
well, but all 3 were replaced recently..

Thanks,

Dan

idle speed?
 

You've done quite a bit of the usual replacing. Try a slight adjustment in the idle speed (does the tach work?). That helped us one time.

alright, how about the rack damper bolt...behind the ip...

is that in good shape. i've read that it can exhibit these symptoms if bad.

I have almost the exact same problem with my 1980 300SD. My next step is a valve adjustment.

Is the problem worse the closer the engine gets to operating temps?

That is symptomatic - at least on my 300CD - of valve adjustment time. As the motor reaches operating temp, the shakes increase.

Most (not all, but likely the majority of) shaky-idle conditions can be solved by adjusting the valves and THEN adjusting the rack dampener bolt.

Have you noticed any smoke indicating unburnt fuel?

There is no smoke at all.. The part that really confuses me
is why would it seem perfect in reverse and vibrate when in
drive.. This to me would rule out the Engine I think..

Thanks,

Dan

82 240d daily driver for 9 years (sold)
73 280 Daily driver for 4 years (sold)
82 300SD Daily driver and 175k miles

Adjusted the valves today and all but 1 needed adjusting.
Helped a little, but the vibration is still there..

I did put in an new rack damper about 1 month before the
problem appeared. The rack damper is all the way in, and not much
happens if I back it out 2 or so turns..

The problem actually gets better with a hot engine.

Inspection of the trans mount shows that this was not likely
changed.. This will be my next guess..

Timing chain stretch is about 4 degrees, so this seems OK

Zero smoke... 27 to 28 mpg on the highway.

Reverse definately quiets down the noise/vibration.

To recap what I have done. New Motor mounts, eng shocks,
shock bushings, filters, pure luber molly diesel purge.

How to tweak the idle??

I am almost stumped.. Lets see what the trans mount does...

Thanks again for all the tips..

Dan

sorry i see now where you mentioned in the first post about rack damper.

how bout just bumping your idle up? what is ur idle set to now appx? i think there's a little set screw near the throttle linkage that you can adjust the idle with...someone chime in to make sure that's the only way.

OR

injector pattern/new injectors perhaps?

I FIXED it!! When I purchased the engine shock bushing I was cheap
and didn't purchase the whole kit... When tightening the shock,
I squished the rubber that goes between the inside cup and the frame
and there was metal to metal contact.. I installed new rubber between
all of the cups and on both sides (total of 4)..


Bottom line is to replace all of the mounts, the engine shocks, the shock bushings
and the rubber between the lower shock shaft and the frame. My car has been
vibrating for over 1 year and I have probably rattled other stuff loose..

The filters, valve adjust and the damper should all be done as well... The car
feel new again!
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