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.

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1979 Thistle Green 300D 272,xxx miles
1984 Orient Red 300 D 4 spd Euro Import - 189,xxx miles
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Lofat Productions
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The shocks are there to absorb the "rocking" you get when you shut off a diesel.....they're just intended to buffer it.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

so likely not the culprit eh?

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

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1979 Thistle Green 300D 272,xxx miles
1984 Orient Red 300 D 4 spd Euro Import - 189,xxx miles
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Lofat Productions
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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

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1979 Thistle Green 300D 272,xxx miles
1984 Orient Red 300 D 4 spd Euro Import - 189,xxx miles
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Lofat Productions
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

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.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

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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