So, I've searched the forum and read the shop manual... but.
How do you determine whether a motor mount needs to be replaced.

Take for instance, the front mount on our '03 GC. I can see the engine side of the mount move when the vehicle is shifted from neutral to either drive or reverse.
How much motion is allowable? Can the left and right hand mounts be measured as far as the height of the engine side to the body side?

And, if the info exists, where?

Recently a shop replaced the transmission on our '99 GC. Now I feel engine vibration and the 'shock' of the transmission shifting. I assume that the problem might lay with the transmission end mount, but how to judge.

Any thoughts?

Thanks, Stan

 

Have someone power brake the engine in all gear ranges and look at the mounts. If the seem to be a lot of movement, replace them. Or if the mounts look broken. If you are feeling a vibration or rumbling sound. Check the motor mounts adjustment, because the exhaust could be hitting the K-frame on the 1999 van.

 

Well, it looks like I have to find a similar van with known good mounts so I can calibrate my eye.
I was hoping that some numerical value might be available to enable my initial eye-cal.
This van will be going to the shop tomorrow... I'll make a point of watching as carefully as I can, without getting under the mech's feet.

Thanks for your reply,

Stan