AWD Opinions Wanted

**Space** · 01-16-2010, 02:33 PM

1998 V70XC

Here's the deal, it's broken.

I need to narrow down what the problem is. Local shops given me conflicting opinions so I thought I'd post it here.

First, I have replaced the drive shaft, serviced the diff and bevel gear. The bevel gear I actually had off the car to replace the torque converter seal. While is was out I drained and refilled it. The end play of the shafts did not seem excessive nor was there what i would consider abnormal play in the rotation.

A banging sound has developed at the rear of the car along with a vibration. The vibration is worst at about 63mph. The bang is associated with lite load on/off throttle. It occurs when traveling at highway speeds when the throttle is fully released to decelerate a bit then picked back up. I also occurs if I slow to round a turn. For instance, apply brake to go around a corner at an intersection and the throttle back up and bang. Rarely does it happen when coming to a complete stop or accelerating from a stop.

Based on my own research on how the system works I have my own idea of which part is FUBAR'd, but would like to know what others have found. I have read several other posts stating extremely similar symptoms with no conclusions. I am not against spending some money to get another 100k out of it WITH AWD.

**holler1** · 01-16-2010, 05:06 PM

Have you removed the driveshaft to see if the noise goes away? That should help narrow the problem down. I am in the process of doing that myself to find a metallic pinging noise near the front center of the car that I think is one of the CV joints or the bearing on the driveshaft. I had a similar noise several years ago and fixed it by replacing the driveshaft's front CV joint.

**Space** · 01-17-2010, 09:24 AM

Originally Posted by holler1

Have you removed the driveshaft to see if the noise goes away? That should help narrow the problem down. I am in the process of doing that myself to find a metallic pinging noise near the front center of the car that I think is one of the CV joints or the bearing on the driveshaft. I had a similar noise several years ago and fixed it by replacing the driveshaft's front CV joint.

The drive shaft is out and no noise. When I first removed the drive shaft I found the front CV boot was gone. I replaced it with a remaned unit and the noise came back. I have since removed it again so not to damage anything further.

This seems to be quite a common noise but I cannot find anyone who has posted the the solution.

**JRL** · 01-17-2010, 11:45 AM

If you think your current driveshaft is a good one, your viscous coupling is probably shot!

**Space** · 01-17-2010, 06:30 PM

Originally Posted by JRL

If you think your current driveshaft is a good one, your viscous coupling is probably shot!

Thats what I think. Actually I think it the freewheel mech. On your recommendation I called Erie and they want $950 for a used one

I can get a new one for $1060.

I really just want to rule out the rear end being the problem.

**holler1** · 01-18-2010, 04:30 PM

Are you sure Erie Vovo wanted that much for a Viscous Coupler? I checked their website and they seemed to be selling a used "viscous clutch" for $375. Isn't that the same thing? They list it under driveshaft.

I finally got my driveshaft out today, and my metallic clicking noise went away. I think it was coming from the driveshaft's front CV coupling again; the same one I replaced four or five years ago.

By the way, I found a thread on Matthew's Volvo Forum that described how to test the VC. This is a quote from DurangoStang- "I looked on the XC site, and found some more information, including a service bulletin on how to check the free wheel (put the car on jacks and see if all 4 wheels spin - at 35mph, the rears should stop spinning) and viscous coupling (jack up one front wheel, put a torque wrench on the center nut, and make sure it doesn't turn up to the specified torque)." I haven't tried this.

**Space** · 01-18-2010, 05:19 PM

I saw the test procedure for the VC and the freewheel. I have to reinstall the shaft to do it.

I called Erie and got a quote of $950.

$375 and I would have bought it.

I may have a new remaned shaft for sale soon for an early VIN 98.

**bronson75** · 01-21-2010, 03:05 PM

I am in the process of doing that myself to find a metallic pinging noise near the front center of the car that I think is one of the CV joints or the bearing on the driveshaft.

I just diagnosed this same problem on my wife's '99 XC. At moderate speeds (sub 55), it sounded like someone was beating on the driveshaft with a jackhammer, the sound was right under the shifter. Pulled the driveshaft, and the front CV has some play, but the main culprit is a bad U joint. One axis is seizing, and it would bind during rotation, sending a shock up the driveshaft into the front CV.

Now I get to have the whole shaft rebuilt, but for now the car is back on the road.

**Space** · 02-09-2010, 10:47 AM

Between snow storms I reinstalled the drive shaft today then did the test for the freewheel and the viscous coupling. The VC required more than the spec'd minimum 50Nm to turn the wheel. The freewheel, however, was unlocking at less than 20kph not the 50kph that is spec'd. Also, there is a lot of clatter from it while it was not engaged.

Now to find a VC on the cheap Erie is out of early 98's