how tell if bad motor mount

[dslpwr]

I have a intermittent vibration in motor sometimes.
Motor has different sound when stopped at light with tranny in drive.
Shift to park noise goes away.
Look like motor is setting a little bit off center.
When under truck looking at motor mount, the spacing is different between the two mount.
Also took nail bar and pryed up on motor mount there is some movement.
Thanks Danny

[HowieE]

Sag is the first indiaction. If they are not the same side to side you most likely have a bad one.
With your pry bar you could move a good mount, but look for sag. There should be clearance between the 2 metal sections of the mount.

[britannic]

When my passenger side header bolts started tapping on the frame, I realized the motor mounts were toast. In fact the rubber disintegrated as I removed them. So I fitted Energy Suspension replacement inserts into the shells and the engine now sits about an 1" higher with better clearance and the driveline angle has improved a bit too.

[pedro]

Turbo Power;

How much trouble was it to replace thr mounts?
How long did it take?

Thanks

[britannic]

I chose to keep the engine installed and jacked it up using the oil pan with suitable crumple protection.

It wasn't that easy, but took me about 3 hours, even without an assistant to hold a wrench on the nuts underneath the mount shells (I used a bungy cord and long screwdriver to hold my wrench onto some of the nuts).

The total time also included R&Ring the mechanical lift pump, which necessitated removal of the pass. side block upper mount bracket - I didn't want to dismantle my Banks turbo system to get at the pump and jacking the engine up makes it easier to get at.

I split the shells by drilling out the rivets, after which installing the poly mount inserts was very straightforward.

[cowboy832]

Energy Suspension replacement inserts Where did you get them? Since my truck is totally stripped down to the frame, I would be interested in using something better than the stock motor mounts when it goes back together.

[britannic]

I can't quite remember which of the 2 suppliers listed below I bought from, but I ordered the Chevy 350 motor mounts, since they didn't list our diesels.

The insert completely fills up the shell, but it fits perfectly in all respects. YMMV, but there's a real difference in smoothness from the drivetrain during driving.

www.Truckperformance.com (http://www.Truckperformance.com)
www.Performancecenter.com (http://www.Performancecenter.com)

[Kennedy]

When they look like this:

http://www.kennedydiesel.com/images/Worn_Motor_Mount_small.gif

Old mount from my 1984 6.2. Pic from my 6.5 Tech tips page.

When they get too bad, the ears of the engine bracket can rub the frame. A brake torque can also find a very bad mount as the engine will really jump when they get extremely bad...

New mount will look like this:

http://www.kennedydiesel.com/images/motor_mount_new_installed_s.gif