XC70 99 thump from transfer case in reverse?

[Duncan B]

Hi all.

I was reversing my trailer up a grassy incline next to my house yesterday. The front wheels on my XC70 99' started to slip a little, then BANG! I heard a thump sound it came from around the transfer case or the rear of the transmission tunnel/prop shaft area.

I'm not sure what this was so I had a look under the car to make sure I hadn't hit something or bottomed out, then did it again... Yes , there is a definite sound coming from this area when reversing and the AWD starts to kick in. I have not experienced anything like it going forwards. But I haven't tried to get stuck on the grass going forwards.

I am not sure the AWD works in forwards or reverse as I haven't had the Volvo for a very long time. It wasn't a steep hill and the trailer was empty. I have had other AWD cars in the past and they behaved a little differently.

I am wondering if anyone else has had this problem, if this is a common failure or just some bad luck. Is this a quick fix or a bigger problem? Is there a way to correctly diagnose the failure? Any help would be awesome.

I am going to have a look under and around the transfer case to see if anything is loose once I can get it up in the air.

[Duncan B]

So after my last post, I noticed a noise coming from beneath the car around the transmission, it made a noise like feck, feck, feck, feck, feck. Kind of sounded like road noise coming from the tyres when you have mud on them and when it eventually all flies off and it stops and is all good. But it was coming from a more central spot with faint vibration through the accelerator pedal and it didn't stop.

I had a poke around under the car. Its the beginning of winter here in Sweden and today it was -5 degrees with limited daylight. Unfortunately I don't currently have a garage so I braved the elements, at least while the sun was shining.

On my inspection I found the drive shaft has come away from the rear of the transmission. It looks like the bearing forward has exited the transmission. Im not sure how it is normally retained, as the section forward was effectively partially hanging out of the transmission but still attached to the drive shaft.

There is a lot of play in the drive shaft with movement forward and aft. Im not sure how much this should move, if this movement is a contributing factor or a result of the drive shaft popping out of the transmission after something else failed.

I will remove the driveshaft tomorrow morning and see what I find on a more detailed inspection. At least I seem to have found the issue, and the source of the noise. Now to fix it.

Anyone else had this experience? Have any tips on getting this drive shaft out with minimal removal of other components? Advice on how much play there should be in the drive shaft? What limits the movement of the driveshaft? (Carrier bearing, circlips.... etc) Any schematics. Also If I remove this will it function in two wheel drive temporarily without any other modifications?

I don't currently have a workshop manual for a v70 xc '99. But any help, tips or comments are most welcome.

Cheers.

[Duncan B]

So today I got the drive shaft out.

On inspection of the drive shaft I found one of the U joints to be extremely stiff and it looks like the bushing or bearing? is beginning to fail limiting the flexibility of this joint. I am not sure if these can be replaced or repaired as the parts seem to be punched in location and don't look like they can be removed. I will see what can be done.

I checked out the transaxle/ angle gear and removed that. I mentioned earlier there was excessive movement in the output shaft bearing. It didn't take too long to remove so that was good. I basically pulled the wheel, the axle retaining bolt, unbolted the two lower bolts on passenger side strut. Released the carrier bearing on the drive shaft and then pulled the axle complete with CVs etc out. I undid the remaining 5 bolts securing the Angle Gear assembly to the transmission and a bump stop. Then after some shimmying it came out.

Sadly my angle gear is buggered. I opened it up to check inside and the bearing inside the casing has self destructed sending pieces of roller bearing through all the moving parts, chipping teeth and rendering it useless. The casing is in good nick, but both gears are in tatters.

I am wondering the cause of this? Does anybody know? Is it anything to do with my stiff u joint on the drive shaft. I have heard volvos 4wds have a habit of failing in this area. Well at least I do now I have the problem and are looking to fix it.

What is the best option for repairing this? I need the AWD, but I don't need to spend the cost of a Subaru on repairing this one. I can see it may be the better option to convert this to FWD. Can I do this by removing the output shaft and blanking it so I do not have to source another Angle gear assembly?

As always any questions or comments are most welcome.

[v70xc gav]

ive a nice newish one forsale

[Duncan B]

Thanks, but I have since sourced one locally with low kms. I will see how it goes.

Out of interest what is your location?

[v70xc gav]

UK south west wales

[Richardkimber]

Excellent post Duncan, looks like you have got on top of the problem. Some questions come to mind.
What is the car mileage ? Do you suspect its the originonal bevel gearbox oil ? Obviously bits in it, but was it black like a thin molasses ?
I do beleive the AWD does work in reverse.
Hope all works out well.