My Cooper has the dreaded canister engine mount BUT it has not leaked yet. At 54K miles could the internals, whatever they may be, be worn and would I benefit from replacing it.

I recently replaced the lower engine mount (first with poly, then back to new OEM because of too much NVH) and installed an upper engine damper. The car still does not have the quiet shake free idle I want and there still is some driveline movement.

I am thinking of raising the idle speed to around 1K since it smoothes out at that point. I have a poly tranny mount coming, which will increase NVH but I understand it goes away after a while.

Any comments are appreciated. Basically I want no driveline movement and smooth engine idle.

 

An inherently unbalanced 4 cylinder engine and no driveline movement? I'd suspect that going to poly engine mounts actually increased wear on the upper mount. Perhaps you're getting some vibration coupling at idle, causing the shake?

 

The poly mounts were in for 5mins. before I took them out. I used to have an 03 Cooper S that had some, as you say inherent vibration since it is a 4 cyl, but it didn't have the yo-yo or jerk of the drivetrain.