I just started noticing a high-pitched whine a few days ago. I thought my bike rack was whistling in the wind on the highway, but I'm pretty sure it's not that. it comes & goes anywhere from 50-65 mph on the road.

even more so, when I decelerate, I get a whine that starts high and drops as the car slows...sort of like a bomb dropping (!!). it's not rpm based, as I can accelerate or shift down to 2nd and it doesn't increase/decrease with the tranny or rpms.

it's not brake related either, as the whine comes even if the car is just coasting down...no brakes applied. I haven't tried putting the engine in neutral, I'll give that a shot on my way home from work.

I was thinking diff fluid maybe? I can't tell where the sound is coming from exactly...sounds like all over, haha.

any ideas? could this be the driveshaft bearing? how do you test that? anything else I should look at?

J.

 

My guess would be that you have a vacuum leak.

 

what makes you say that? the whine doesn't change w/rpms. and it doesn't do it when the car isn't moving...not sure how a vacuum leak would stop if the engine doesn't.

J.

 

Sounds more like the rear end is going out to me BUT...it could also be a bad tire. Rotating the tire front to back and listening for a change in tone is a cheap test. Yes, the differential could be low on gear oil but more likely if the noise is from there it's failing internally. The rear end oil slings out and lubes your rear axle bearings as well, so it would be a good thing to check the level. To locate the noise, I'd recommend taking it to a small shop that would run it up on the lift. Keep in mind that the suspension will be unloaded and the sound may not be duplicated. Also, a failed transmission mount can throw the driveshaft out of alignment...motor mounts too to a lesser degree.

 

yeah, I was gonna jack up the back and see if I can get it to do it, but with my luck, it probably only works when there's load on the rear tires...

supposing it's either the bearing or the ring/pinion...are they easy to get a hold of? I used to own Jeeps, so I know the aftermarket is good for those, and I've even helped replace one before. I just don't know much about the rear ends in these Volvos...

J.

 

It's a Dana 30 rear end so yeah, pretty straight forward. Honestly, the simplest thing is to swap in an entire rear axle assembly. Only takes a few hours.

 

trouble is finding one that is in better shape than mine. mine's only got 165k on it...

J.

 

Mileage doesn't kill 'em as quickly as poor maintenance and low fluid does. The trick is to find one with no signs of long term leakage. To swap the guts, you have to remove the calipers, pull the axles out of the carrier bearings (now's the time to replace rear axle seals if leaking), pull the ring gear assembly. Remove pinion gear.

 

Backlash setting on the ring and pinion for the DIY'er is not the easiest thing to do if you plan on being able to drive the thing for any real amount of time. I concur the best thing to do is swap the whole rear axle out with a known good working replacement.

 

swiftjustice44, I know this is a very old thread but I was wondering if you could give me some advice. I'm trying to swap the differential from a '93 960 wagon into a '93 940 wagon to raise the gear ratio(better mileage). It was an easy swap, as many have said, but I did not pull the pinion gear from the 960 and I seem to have a little more backlash than the stock setup. Problem? Also, I can't find the posts on doing this but they mention taking the right shims with you when you pull the new one. But I can't see any shims that could come off. Are they between the ring gear and the bearing?