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.
98 Outback with AWD Problems- rear wheel power only
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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.
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.
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.
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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.
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.
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!
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??
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In the 4EAT with the multi-plate clutch transfer system (not VTD), the AWD transfer clutch controls power to the rear drive shaft, only.
The front drive shaft (pinion shaft to the front differential) is permanently connected via the reduction gears to the output shaft of the transmission. If there's no drive to the front while there is to the rear, there has to be a problem in the front drive system; that is, at the reduction gears, through the pinion shaft, the front differential, and the two front half axles.
(Put differently, it's impossible for one or both rear wheels to be turning while neither front wheel is turning, unless there's a mechanical disconnect/break in the front drive train.)
Your car is equipped with a FWD socket in the engine compartment. It should be near the firewall on the passenger side. Insert a fuse in the socket. This should disable the AWD (prevent the clutch from engaging) and turn on the FWD warning light in the instrument panel.
With the fuse installed, the rear wheels should/will not get any power. Now, you can see if the fronts work at all. (If the front drive is intact, the car should move almost normally -- it would be the same as a front wheel drive car. This, of course, assumes that the transmission itself is working properly to begin with.)
The front drive shaft (pinion shaft to the front differential) is permanently connected via the reduction gears to the output shaft of the transmission. If there's no drive to the front while there is to the rear, there has to be a problem in the front drive system; that is, at the reduction gears, through the pinion shaft, the front differential, and the two front half axles.
(Put differently, it's impossible for one or both rear wheels to be turning while neither front wheel is turning, unless there's a mechanical disconnect/break in the front drive train.)
If there's a disconnect in the front drive (such as a broken axle), the AWD mechanism will sense this as a spinning front; it will increase the pressure on the transfer clutch, causing the rear wheels to push the car. Once the car is rolling, there's no way to know if the fronts are working or not.
The AWD system does not control power to each wheel (that is, side-to-side). It only controls power to the rear drive train, while the front is, normally, always powered.
Your car is equipped with a FWD socket in the engine compartment. It should be near the firewall on the passenger side. Insert a fuse in the socket. This should disable the AWD (prevent the clutch from engaging) and turn on the FWD warning light in the instrument panel.
With the fuse installed, the rear wheels should/will not get any power. Now, you can see if the fronts work at all. (If the front drive is intact, the car should move almost normally -- it would be the same as a front wheel drive car. This, of course, assumes that the transmission itself is working properly to begin with.)
Problem solved! Thank you all for your help. Plain OM, CarDoc, RasterMan, and Canubaru you guys are awesome in explaining how the all wheel drive system works and thus helping diagnose the problem. Easy fix...we added trans oil to bring up to normal level. It was unable to function correctly without the right pressures or level of fluid. I was incorrect in my original post description of the problem by stating that only the rear wheels had power. It did appear so but upon further investigation that was not true and I do apologize. I hope this thread helps anyone else dealing with any of the same issues. It is a great day today.
Yep. Where's the weak spots on these?
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