I just finished doing the motor mounts on my 80 240D. Boy was that fun...NOT. I don't know if I was doing something wrong or not, but there were times that I had the front tires off the ground trying to get enough clearance to get the mount in.

Does anyone know if I was doing something wrong? I had both mounts out and still couldn't get the engine up enough to slide the mount in, especially on the drivers side.

I had to use a pry bar to get that little more clearance to get them in.

Boy, what a difference in the level of vibration. This car was so bad that I have gotten into the habit of kicking the shift lever into neutral at every stop to halt the vibration. Now the idle is very smooth, even in gear.

Glad I did it, but it was not fun.

Joe

240Joe:

Did you also replace the transmission mount?

Before you replaced the mounts, was it idling very rough in gear but not in Park or Neutral?

How did the old mounts look?

TIA.

I didn't do the tranny mount. I thought I would do the motor mounts first, and see how it worked. When I tried to look at the tranny mount, it had so much gunk on it, I would have to clean it before I could tell how bad it was.

I'll probably just replace it when it warms up in 3 months or so.

The symptoms were exactly that...lots of vibration at idle when in gear. If you kicked it out of gear, it would smooth out.

The old ones were were really bad. They were not completely broken, but they were cracked and shrunken down. I don't have any idea how old they are.

HTH.

Joe

I am having a little trouble understanding this.

I always thought bad motor mounts will cause vibration, whether in P, N, or D. A bad transmission mount would cause vibration in R or D but not in P or D.

Apparently your experience does not support that.

I believe the reason vibration is a lot worse in gear is because you have torque on the engine, putting a compression on one of the mounts and tension on the other. Since the mounts are shrunken down due to years of weight and aging rubber, you no longer have the clearance necessary to keep the metal parts from hitting each other (engine to the frame). When they touch, lots of vibration is transmitted from the engine to the frame.

I could be wrong, but it makes sense to me.

thanks
Joe

240Joe:

That explanation sounds good.

I have an intermittent vibration in gear on my 1987 300TD. The driver side mount looks pretty good and I cannot see the one on passenger side without removing the belly panel, etc. I thought it was the transmission mount (also under yet another belly panel).

Will take a look when the weather warms up.

240Joe,

When you get ready to jack up the engine, there is a snubber type mount, at least on manual transmission cars, that connects to the bell housing flange. You have to take this off (and on my 1982 240D it was seriously degraded by a rear seal oil leak that was slowly turning the rubber parts into a tar like substance) to allow the engine to continue to go up. I also found that taking the driver's side mount off and replacing it by lifting and rolling the engine (put the jack off center on the oil pan, and you get a lifting and twisting motion of the engine as you jack the car up)with the passenger side fasteners just broken loose gave me the extra room I needed to get the mount in and the little sheet metal shield back on.

It sure does make a difference, as my car's driver side mount was completely broken and contributed to thrashing the starter to death. When I replaced the starter it was nearly in three cylindrical pieces.

Glad you made it. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

The change I got when I replaced my motor mounts was amazing. When I took it around the block after replacing them I had very, very little vibration. However after a 3 hour drive to Dallas the next day, something interesting happened. Instead of feeling vibration when I am idling, the the car now vibrates when I am accelerating. Before I put my new motor mounts on, the problem was the exact opposite (vibration at idle, no vibration at acceleration). It is especially bad at low rpms and when I am turning right, but it levels out at higher rmps, when I am not accelerating or when I am turning left.

My goal this weekend is to check to see if I might need to retighten the new motor mounts, but it doesn't really make sense that it would be the motor mounts. We'll see though.