92 Voyager AWD- Grinding Noise

Quite a surprise today, taking my AWD into town. All of a sudden, I developed what sounded like a grinding sound below the passenger floorboard. It appeared that the right rear passenger wheel was locking up! I came to a halt and the feeling of a lockup and the noise stopped.

I limped into town and a friend joined me for the journey home.

There were no leaks anywhere.

It appears the overrunning clutch housing was hot as a depot stove!

The sound is like pushing a piece of cardboard into the blades of a fan!! (Not good).

It sounds like grinding inside the transmission. Slow down and stop, wait a few seconds and take off and then it re-appears again.

All fluids were checked before I put this vehicle on the road.

Any help desperately requested...

Reply to
Caravan Guy
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We're just sitting at computers. We can't help. You're going to need somebody under your van with some tools, instead of guys at computers.

Reply to
Joe

Sounds like a transfer case problem. Ted M. and some others on this NG have experience with AWD, and may be able to help.

-Kirk Matheson

Reply to
kmatheson

Kirk: Speaking w/ Ted about it. You just might be correct. Maybe even a mount problem. Noticed something today...front shaft may have struck top of the frame rail. I may know something later today. Taking the car up on a hoist; going to see if I can get it to do the same thing it's been doing. Thanks for your help.

Reply to
Caravan Guy

Under the van, it appears the front drive shaft has hit the frame. Tried using crowbars to make it move, so such luck. Ted had a similar problem, but mine was intermitent. Drive a bit, then all fo a sudden, the shaft hits the bottom of the van. I think Ted shimmed up the front mount and pretty much solved his problem. My front mount is not good, the left engine mount is weak. Will replace and see what happens. Carquest does not have them, so NAPA is my next stop.

Reply to
Caravan Guy

I did shim but I still have the problem, however it only appears under heavy accelleration (which I can easily avoid) In my case my frame is bent so there is nothing more I can do (except take it to a frame shop) and the front mount is shimmed as much as possible, also I put a bolt in the front mount above where the normal bolt goes, in order to prevent the front mount from compressing as much as it normally can.

Unfortunately, the aftermarket engine mounts are no good here, they use softer rubber and will compress more than the OEM mounts, making the problem worse.

The way the geometry works is this:

On accelleration, the resistance of the front 2 axles tends to force the front of the engine up, and the back of the engine down. The 2 side mounts are a bit behind the centerline of the engine, so what happens is when all the mounts compress the back of the engine will go down.

If all mounts are stiff and fresh, and the engine cradle is aligned, the compression of the mounts is not enough for the driveshaft to touch the bottom crossmember. When the driveshaft touches it transmits all the vibration in the engine to the chassis and the body amplifies it, and it sounds like someone is sawing at the body with a dozen files. Worse, the second the driveshaft is slapped against the bottom crossmember it imparts a twisting force on the engine which pulls weight off one of the front wheels, causing it to slip, as soon as the wheel slips the powertrain unloads and the shaft snaps back up off the crossmember, whereupon the wheel reloads and the cycle starts over again. You end up getting massive wheel hop, bang, bang bang bang bang.

If the mounts get weak the compression is enough for this to happen on heavy accelleration. The worse the mounts get the more this happens.

You can shim the front mount with washers about a half inch. You can shim the side mounts with washers a bit less than a quarter inch. Shimming the front mount pushes it down, shimming the side mounts push them up. Start by shimming the side mounts with a single washer on each bolt hole and see if it stops. Then start adding washes to the front mount, testing each time, until it either stops or you run out to the end of the bolt.

If you have to replace mounts, get the stiffest ones you can find. The front is the critical one.

Ted

Reply to
Ted Mittelstaedt

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