Engine shocks - what is their real function?
 

Greetings all,

A few weeks back I replaced my engine and transmission mounts on my 1979 300D because of a problem I was having with the engine accelerating when going up a steep short incline (like that of a driveway or parking entrance) as well as with hard left turns. It seems in the time that I had owned the car that the issue was getting worse and more frequent. On the advise of a few board members I replaced the mounts. While the problem seems to have lessened somewhat it is not gone – and it is bugging me to no end. As I am sure most will agree – the only time I want the engine to accelerate is when I am stepping on the accelerator pedal.

I noticed while I was under the car that there are these engine shocks (which you have to disconnect to change out the mounts) and I was wondering how these play into the mix. They look like they are original engine shocks and bushings. Could this be the reason for my problem? How much of a roll do the engine shocks have in supporting the engine and keeping it from moving around?

I want to get this situation (as well as a few others) worked out before the warmer weather hits and I have to start making a few longer road trips.

Some other notes – the old engine mounts were in good shape. They were only slightly compressed with no tears, mushy spots, or cracks. I still replaced them as by the time I was able to inspect them they were already out of the car.

Like I mentioned I also replaced the trans mount. Now it doesn’t seem like this part would really have any impact on the problem described but, I don’t know that for sure either.

Also – when I turn left while at speed I feel some vibration that wasn’t there before.

I do plan on getting the car up on jack stands again this week to inspect again – but I am at a loss here. I mean engine mounts are a PITA to do but it’s not rocket science. I really want to solve this problem so I can move onto other equally fun jobs like the rear suspension and take some road trips.

Appreciate the help.

The shocks are there to absorb the "rocking" you get when you shut off a diesel.....they're just intended to buffer it.

so likely not the culprit eh?

I am hoping to avoid a shop visit but at this point I am stumped.

Vibration Dampeners
 

They dampen the vibration of the engine. :)

"PLEASE", post pictures of your accelerator linkage.. :)

Incorrect assembly, wrong linkage, mis-adjusted linkage and/or damaged linkage are possible. :(

will do when i get home (weather permitting).

i noticed that there is much linkage and following it didn't give me any clues - of course i know not what i am looking for (aside from the obvious). i can say it looks somewhat worn.

thanks,
Scott

shocking
 

they arent that expensive so i would replace them... it might do the trick. it seems as if you have done everything else.

I too was thinking linkage. The 79 MY had the linkage run behind the engine, under the manifolds and up and over the valve cover, right? a lot more twists and turns for it to get hung up on if the ball and sockets are all dry. Try lubing them all and see if that helps.

Hi...those tiny shocks are to stop the sympathetic bouncing of the engine whilst it is running and otherwise changing loading.

The mounts are of solid rubber and have no inherent damping unlike the hydrulic mounts used in most vehicles now.

I have many customers without these shock working and indeed some completly missing with no adverse reports from the owners.

As for your 'unintended acceleration', if there is no free play between the engine mounted bell crank and the cross rod to the fire wall, this will do as you say.

Whilst mounts can seem okay, they are often compessed enough to cause metal to metal contact when turning or over bumps enough to cause a slight vibration in the chassis.

Also check the rear transmission mount too.

The metal heat shield I have found, does not seem to make them last any longer...in fact they often trap engine/diesel oil which attacks the rubber.


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