98 Outback with AWD Problems- rear wheel power only

[drivesubarus]

Our 98 Outback Limited is having some issues with the AWD. Rear wheels will spin on the snow and ice and front wheels have no power! What on earth could be causing this? This is an occasional problem as it does work properly but is more recently having issues. Again, the rear wheels do have power and spin while the front have no power. When it does this the fronts will suddenly grab as the engine is reved and make clunk noise. Someone please help.

[canubaru]

what trans??

a busted front axle will cause this situation on an auto trans car.

[drivesubarus]

Originally Posted by canubaru

what trans??

a busted front axle will cause this situation on an auto trans car.

I'm not sure what trans. model. Its auto. not manual. Wouldn't broken front axle make noise all the time? The AWD works sometimes as it should, then other times the rear wheels only have power until the front ones suddenly engage(with a clunking noise). Thanks and any help with this is appreciated.

[rasterman]

There was only one auto for 98 so that narrows it down enough. Inspect the front drive axles. It sounds like one is broken or disengaged, the clunk etc is the AWD making a sloppy correction to a problem it wasn't trained to deal with.

[drivesubarus]

Originally Posted by rasterman

There was only one auto for 98 so that narrows it down enough. Inspect the front drive axles. It sounds like one is broken or disengaged, the clunk etc is the AWD making a sloppy correction to a problem it wasn't trained to deal with.


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I will check the front axles tomorrow although I have doubts one can be broken since the problem is erratic and there have been no other noises. Keep the ideas coming in...need to get this solved.

[plain OM]

When looking underneath, also check to see if either of the two front axles has pulled out from the differential (as rasterman mentioned above). This has been seen here before.

There's a short "stub" shaft between the inner (larger) CV joint and the differential. The stub is splined, and engages the side gear inside the differential. Sometimes the stub gets pulled out, perhaps because of a stiff inner sliding CV joint, and the splines become disengaged.

The inner side of the inner CV joint should be very close to the differential -- the stub shaft should not be visible.

If you grab the outer case of the inner CV joint and push/pull on it by hand (only), it should not move in or out from the differential. If it can move away from the differential, the stub shaft can become disengaged from the side gear.

The inner CV joint outer case is connected to the stub shaft by a "roll pin". If the roll pin is missing, or broken, the CV joint can move in and out on the stub shaft.

[drivesubarus]

Okay, so we were finally able to check out the front axles. Nothing out of the ordinary other than a torn inner boot. The axles are tight and splines connected and in the differential as they should. Upon further testing of the AWD today here are some observations: The problem happens from a dead stop or standstill, seemingly not while already moving. At times the rear wheels only spin. Sometimes right side only. Sometimes maybe even fronts spin. For some reason it is not distributing power correctly to all fours as the car should and always has until recently. While accelerating it will engage all wheels (with a big clunk sound) and then work properly. This is an intermittent problem as it works as it should at times and has amazing traction. Someone give me some more troubleshooting ideas please. I really appreciate the help everyone!

[cardoc]

Have you checked the transmission fluid level?

[drivesubarus]

Originally Posted by cardoc

Have you checked the transmission fluid level?

That's my next step. I'll check the level or change it and see what happens. From what I've read the other thing it could be is maybe the clutch that controls the awd??

[cardoc]

Yes. MPC assembly controls torque transfer and is operated by fluid pressure.