This might apply to the xj's as well but I dunno. On the factory motor mounts is it common for the thin layer of rubber to break / rip? Is this an indication of the mount going bad or is this a common occurrence and does not affect the functionality of the mount. I replaced my mounts about 6 months ago, I did not replace the trans mount like I should have. There is a little bit of play when I rev the engine but it could be normal.

 

If the rubber is ripped and allowing the sleeve insert to lift.. the mount needs replaced. They will develop cracks as they age, does not mean it's bad.

A little play will be normal.

 

If it is the paper thin rubber that is in the voids then it is not a problem, that is just flashing from the moulding process.

 

That is what I assumed but I wanted to be sure.. so if the round part of the rubber mount actually moves in the metal housing it needs to be replaced?

Just want to be sure so I don't spend 4 hours replacing something that doesn't need replacing...

 

Right, if the rubber that holds the metal sleeve looks funky and broken then it's time to replace it.