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850 diagnose awd

Could anyone point me to a link or explain how to diagnose/check my awd system on my 1997 850 awd?

There is not much info regarding the 850 awd system but from what I can tell it's the same as the early v70's.

I have no access to a lift but I do have a pit at my father's that I can use, I also have no jack stands.

I have tried spinning the wheels on grass and the front wheels spin without the rears moving.

I have jacked a rear wheel up with the car in neutral and the wheel only turns a cm or 2 and I can hear movement from the prop shaft.

With the car in neutral I was unable to turn the propshaft.

I found a service bulletin
That explained a process to test the Viscous coupling.

Ensure that the viscous unit remains at room tempera-
– Raise the left or right-hand front wheel so that it rotates freely. The other wheels must be in contact with
the ground.
– Select neutral.
– Position a torque wrench horizontally as illustrated.
Read the torque value.
Note! It is important that the torque wrench points towards the center of the wheel to provide the correct
torque reading.
– Turn the torque wrench half a turn (180) clockwise
with even torque for 25 seconds.
– The torque must be GREATER than 50 Nm ( 37 lb ft)
during the entire turn.
The test method assumes that all the other components
included in the system function correctly. If the torque is
below 50 Nm (37 lb ft), the viscous coupling is outside
the specification and/or damaged.

Would this test work for my car? And I remember reading somewhere that the specs where wrong in the bulletin.

I am considering removing the prop shaft today until I am certain how to diagnose and check the system.

Thanks in advance.


  • Ex850RSnoopy (@Ex850R) Somewhere Over the Rainbow. Melbourne.
    Talk to @Rob , he has the awd convert C70 and just sold the 850awd. Rob fixed cheaply what is generally thought to be too hard. So many just give up , say it's too hard and make a fwd out of them. My V70R project will stay awd once I check it all so I will be watching this space to see how you go!
  • RobRob (@Rob) - Lockyer Valley, SE Qld
    if you park on grass and drop the clutch (or accelerate very quickly) you will still spin the front wheels. The difference is that the car will still accelerate rapidly until the wheels stop spinning where a FWD would just continue to spin.

    I would expect that the drive sleeve between the transmission and angle gear is worn. this is very common. fortunately there is an upgraded genuine sleeve available. it all depends how badly worn the splines on your gearbox and angle drive are.

    Checking is easy enough but does involve pulling out the tailshaft, draining the transmission and removing the rh axle then pulling the angle drive out from underneath.

    Unfortunately there is really no other way to test for a worn spline.

    I can certainly give you tips on repairing it should you find it is worn.
  • Thanks rob, yeah tried the grass, the front wheels just spin... No forward momentum...

    I don't have the facilities at home to do this so will have to do it at my father's garage. Is there any thread with the details you mentioned for checking the spline/sleeve?
    Am I correct in understanding that it's the same system as the early v70's?
    Thanks again

  • RobRob (@Rob) - Lockyer Valley, SE Qld
    yes. all P80 AWD systems are identical
  • edited April 7
    Hi Rob,

    I just joined, mainly because OZ Volvo seems a good source for information that I can't get locally. I live in Whistler BC. We use older Volvos in my advanced driving school. My personal car is a 1997 850 5-speed AWD, one of only 214 imported to North America. They all came to Canada. Mine looks stock, but brakes and suspension have been updated, it, still a very satisfying car to drive.

    This spring, the 850 started making a thumping noise from somewhere in back, only while turning with quite a bit of steering lock. We took out the driveshaft and the noise went away, but I want to keep the Volvo AWD. Any ideas? I haven't been able to find a part number yet for just the bearings. Also hard to find whether the driveshaft is the same as on the 1998 V70.

    Any help from you or other members would be greatly appreciated. Volvo dealer hasn't been much help.


  • gavinhGav (@gavinh) Parmelia, Perth
    Sounds like the front cv joint on the drive shaft,
    Its easy to replace if you do it your self, while the drive shaft Is out repack the other one.

  • Thanks, I'll have a look at the shaft this evening.
  • That's an old thread revisited. Might take Rob a while to respond to that.
    If sound was from back wouldn't it more likely be the rear diff?
    I know car was steering and front cv joints will make noise under lock but noise was from back and was ok after taking out shaft so problem is obviously something to do with either of:

    1- Viscous coupling

    2- worn splines on shafts?

    3-rear diff and rear drive shafts

    4- "the drive sleeve between the transmission and angle gear is worn" as rob said

    But you are in the right country to get the problem fixed with colarado drive shaft offering very cheap freight within US. Here in Australia it costs us around $800 to get a balanced shaft from US.

    Talk to Colarado drive shaft and tell them symptoms - they may be able to pinpoint it for you.
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