98 V70 X/C AWD Bad rear differential

pgalli92 · Post by **pgalli92** » 20 Jun 2012, 19:53

Hi,

I've had my volvo v70 for over 2 years now and absolutely love it! I'm at 224k Miles and would still like to keep it going. About 4.5k miles ago I was driving on the highway heading to work and heard a slight humming noise and thought nothing of it but as I slowed down off the highway it got louder and louder. I stopped and noticed my rear differential was leaking gear oil and took it to the closest shop where I had them look at it. They said all the gear oil leaked out and the gears are completely shot in it and recommended not driving it at all. Well I kept driving it and am currently driving it, I have put about 4.5k miles on it with a bad rear diff. Lately it's been getting louder so I want to fix it.

One shop quoted me $700 which includes labor and parts + taxes. But a friend of mine suggested to just remove the driveshaft and convert it to a FWD. I figured this wasn't possible simply because the gears with in the rear differential are already completely shot as they hum loudly and grind at slow speeds. It will also occasionly "pop" and jolt forward slightly while driving at around 30-40mph, only when the humming is very loud though. Everything is fine with the volvo besides a slight oil leak in the front but I'm not too concerned with that currently.

Is it possible at this point to simply remove the driveshaft and leave the worn gears in the rear differential and ride it like that? Or am I forced into replacing the whole rear differential?

Thanks,

Pat, 1998 Volvo V70 X/C AWD

Post by **MoVolvos** » 20 Jun 2012, 20:03

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I recommend you remove the old fluid and replace it with this
http://www.pelicanparts.com/catalog/sho ... co_pg4.htm

http://www.pelicanparts.com/catalog/sho ... detail.htm

Blessings,
BKM
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pgalli92 · Post by **pgalli92** » 20 Jun 2012, 20:23

Well, there is currently no gear oil in the differential as it all leaked out and I never put more in as it would have just leaked it all out. I was just thinking if it's possible to pull the driveshaft and run it as a FWD but will the worn out gears/differential still make noises even if it isn't receiving power?

Post by **MoVolvos** » 20 Jun 2012, 20:34

pgalli92 wrote:Well, there is currently no gear oil in the differential as it all leaked out and I never put more in as it would have just leaked it all out. I was just thinking if it's possible to pull the driveshaft and run it as a FWD but will the worn out gears/differential still make noises even if it isn't receiving power?

The driveshaft puts energy/heat into the rear differential when it is functioning. Without the D/S the gears are still rotating so it still requires lubrication. Take care of the leak and Fill ASAP!!!

Blessings,
BKM
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pgalli92 · Post by **pgalli92** » 20 Jun 2012, 20:38

Thanks for your speedy replies,

I believe it is too late to save the differential at this point as I have been driving it with no gear oil in the rear differential for over 4k miles now and I can hear the gears are shot especially at low speeds. I just never fixed it because I didn't have enough money and it was only a slight whining noise but now it gets loud at points and becomes very annoying. So my only route is replacing the entire differential?

Post by **MoVolvos** » 20 Jun 2012, 21:00

pgalli92 wrote:Thanks for your speedy replies,

I believe it is too late to save the differential at this point as I have been driving it with no gear oil in the rear differential for over 4k miles now and I can hear the gears are shot especially at low speeds. I just never fixed it because I didn't have enough money and it was only a slight whining noise but now it gets loud at points and becomes very annoying. So my only route is replacing the entire differential?

Not sure where the leak is but perhaps you can temporally patch that up or just pore some in. If the noise subsides considerably there is still hope for it. I've seen Swepco remarkably save what most would considered problems that are beyond repair. That aside just get some Generic/Approved Fluid in there and see what it sounds like.

Blessings,
BKM
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Post by **jimmy57** » 20 Jun 2012, 21:04

Look on this site. A few 98-2000 XC's have been listed as parting out. I don't recall seeing anyone ask for the diffs on these so maybe one is available.
The rear diff is not a terrible job to replace.

pgalli92 · Post by **pgalli92** » 22 Jun 2012, 23:11

If I were to replace the differential, would I also need to replace the half shafts & drive shaft because they connect within the differential and since my diff is shot wouldn't the gears on the ends of the d/s and cv shafts be worn as well?

Post by **jimmy57** » 22 Jun 2012, 23:23

No, the halfshafts are splined on the ends and those splined ends insert in the diff side gears and not move relative to those gears. i would not expect them to be worn there. They may otherwise be worn but rear halfshaft CV joints are very long life units unless the boots are leaking the grease out.
The driveshaft from the angle gear back to the viscous coupling on the front of the diff may need attention or replacement.

pgalli92 · Post by **pgalli92** » 24 Jun 2012, 16:01

I did a bit more research and found out that you can remove the driveshaft, and remove the rear cv half shafts so the differential would basically become dead weight and nothing would be spinning the gears within the differential at all. I don't see a problem with removing the driveshaft but would it be safe to remove the rear axles?