When to replace engine mounts?
 

My vehicle is a 1991 300SL with 97,000 miles. For the last month or so, when I start the car, something seems to momentarily rap against the frame somewhere on the right front underside for a moment or two. I've checked the exhaust and it is tight. Has anyone in the group replaced engine mounts on a 300SL / 320SL? If so, what were the symptoms and at about what mileage did you change them? Is this a DIY job? I'm a reasonably good auto mechanic and have tools. Thanks. Tod

I would check the cat heat shield.

If your motor mounts were worn, you'd feel it with an unusually rough idle being transmitted through the cockpit...

Thanks....I will look at that. Actually, I've noticed an idle that is getting rougher and the accelerator pedal is binding a bit at the start of it's travel. These things change so slowly you aren't really aware of them until they get bad enough and then you finally think. "this isn't right' . I was hopeing someone would post at what mileage they encountered engine mount troubles on a six cyclinder SL. In any case, it'll have to wait until next spring. The salt will be flying here any day now, so I've put the car into winter storage. Up here in Wisconsin, for every inch of snow we get, the highway crews spread an equal amount of rock salt on the roads, thereby disolving the sheet metal off of every vehicle that moves. That's why we proudly call it "The Rusty State".

I changed mine on a '90 300SL at 115K miles because one of them was beginning to leak fluid. It was straightforward and not difficult at all.