Re: Engine mount advis please
I've had the same issue on several mounts. I believe the main problem is poor quality parts; i.e. the rubber is not properly bonded to the backing plates (same problem occurs with a lot of aftermarket 'stock' exhaust mounts).
One thing that helps is to adjust the clearance on the top mount; if the gap is too large this allows the weight of the engine settling to put a large side load on the lower mounts, which (at least) contributes to the 'shear' load on the mounts and drooping and delamination. IIRC, the spec is for a 0.015" gap; installing aftermarket parts can create a gap of a quarter-inch or more. Originally, there were shims available to be placed under the backing plate of the upper mount; I have not found them to be available at any of the 'usual suspects' here in the 'States. I took some large--approx. 1.5"--fender washers and cut notches in them so they could slide past the stud the holds the upper mounts (you can/should only do the adjustment after the engine is installed as the gap varies). This seems to have helped, as when the engine settles more of the weight is carried by the top mounts and the shear load on the lower mounts is reduced.