I am trying to track down a rough idle in my 82 and decided to check the motor and trans mounts.

No obvious external cracked or broken rubber on any of them.

At rest I can slide a 3/8" diam rod between the driver side motor rubber and the upper metal bracket and maybe a scant 1/4" on the pass side.
When I jack up the motor, the upper brackets on both sides lift up about and 1/8"

The trans mount at rest sits with about 1/4" slots on the rubber part.
When trans lifted the gap also increases a solid 1/8".
There is fluid below the mount but the tranny pan gasket seems to be leaking so there is fluid on things
The mount rubber does not appear wet.

The engine shock has some old residue on it but once again fluids have migrated from other engine parts so I am not sure of this either.

I believe these components are originals as everything else was or still is.

The car rides and handles great it just has the lumpy idle.

I have yet to pull my injectors till I order heat shields and some other parts, like maybe motor mounts.

What is the opinion here?

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

When a mount is shot, it usually manifests itself as a deep vibration in the chassis when idling. Sometimes the vibration is only present when you put it in gear and not when idling in neutral or park.

Also, if you have a vibration that clears up when you put the car in reverse that's a clue as well.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

It still shakes when in gear F or R but clears up as soon as I start to accelerate

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

1984 300d turbo 147k
rePlace the trans mount the same time diy

Actually it idles pretty smoothly in neutral but shakes in D or R. Trans mount?

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

Any pics of the mounts? Reason for there to be less vibrations in neutral could be the increased rpm's.

If the motor mounts are old or unknown, then change these first. Cleared my 81 300SD up. I am not sure how accessible the 6 mm mount screws are on a 240D. On mine i had to remove the engine mount arm to access the driver's side inner. Don't want to strip these.

The engine mounts only seem to last a few years; doing mine on my 1982 diesel made the car sooooooooo much more driveable. Worth it.

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- Brian


1989 500SEL Euro
1966 250SE Cabriolet
1958 BMW Isetta 600

I just did mounts on a pair of E300's.

MY99, nasty shake thru the steering wheel at idle. One mount obviously colapsed, but both were bad.

For the other car MY98, it had a hint of a shake at idle. We did both mounts off the bat, instead of one at a time. Mounts didn't really look bad. Maybe down only 3/8". Replacing the mounts made the steering wheel idle shake disappear.

Wasn't a hard job. Helped to have 2 people. We did each car in under an hour.