M112 Motor Mounts ......Difficult or easy?

[300B]

Hey gang,

I am contemplating changing my engine mounts and possibly my tranny mount too however I haven't read too far into how difficult or easy this job could be.

What's the verdict?

Car's a 99 C280 btw.

[mbdoc]

Takes a dealer tech 2-2.5 hrs on a rack.

[deanyel]

2.5 hours by a dealer tech on a rack can, in my experience, translate to 3.5 hours for a DIYer, or 8 hours, or completely impossible, depending on the task. I know absolutely nothing about your car but just finished a 124/119 motor mount job which is a very tight job, and it was a struggle once again, in spite of having done it several times before. But a lightbulb came on during the job which I haven't tried yet. It occured to me that I should be loosening the top bolt from above, not from below. I think others have done this I've never been able to get the leverage from above to loosen the top bolt. I've always worked from below and it's a struggle.

But the new (at least to me) idea is this - get a 1 by 3 or similar piece of wood, maybe a couple feet long, drill 1 inch holes in it every couple of inches, C-clamp it on the frame rail (pretty big C-clamp) or somehow wedge it nearby, then get a 24-36 inch long 1/2 galvanized pipe, put the bottom of the pipe in one of the holes, and use it as a lever against your rachet handle, or whatever wrench will fit in your space. It might look impossible with the engine in place but the top bolt is much more accessible once the lower bolts are out and the engine is raised. You might then have to take the motor mount out from below but you could at least take the upper bolt out and put it in from above. Loosening and installing the top bolt is in my experience the toughest part of the job and working with a good lever from above would make the job considerable easier, it seems to me, but I haven't actually tried this yet.

[glenmore]

I did the motor mounts on my 1991 300CE w124/m104 and the big hangup as always is the drivers side top bolt. I wasted an inordinate amount of time going back and forth between above and below trying to get this bolt and finally did it quite easily from above with some extensions and a flex socket. You just have to be gentle here as you thread the extensions thru all the delicate throttle linkage. A helper would be nice to seat the socket from below as you drop it down.

I've glanced at the motor mounts on my 2000 C280 and access looks to be a lot worse so not looking forward to that repair.

glenmore
1991 300CE
2000 C280
1990 Ls400