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240 Rear Differential Whine

S

sheepbleat

Member
Joined
Nov 16, 2020
Location
Brooklyn, NY
I?ve got a ?91 244 that has a steady whine from the rear end that seems to increase as speed increases. I asked the go-to old Volvo mechanic in this neck of the woods and he was fairly certain it?s the rear diff. He also said he doesn?t often see issues with the rear diff on 240s, so I?m definitely scratching my head a bit.

The car has less than 150k miles on it, but whoever had it before me didn?t exactly baby it.

I?m gonna swap the diff fluid, replace the gasket, and take a gander at what?s going on in there tomorrow. Any other thoughts or tips about what this whine might be from? I?d love a solution that doesn?t involve hunting down a new differential.

Thanks TB!
 
I just swapped the rear axle when mine started to wine due to being low on oil. Pulled one from a decent looking car at the junkyard, dropped it off at the Volvo shop to have the seals replaced (didn't want to deal with it myself) and had a friend help me to swap it.
I would just drain and fill the diff and not worry about the gasket if it's not leaking. The wine is not likely to go away but you can still drive for a while and prepare for eventual swap.
 
Driveshaft center bearing?

I'm also surprised when people have problems with these, given how robust they are and how relatively little power these engines make. You know the car's history though, and as they say, **** happens.
 
I used the Lucas gear oil. They claimed it helps quiet a whiny diff. It really did help it and eventually over time it seemed to completely go away. Make sure there are no leaks.
 
Thanks all. Gonna crawl under there to swap the fluid and take a gander at the magnet tomorrow. Will let you know what I find.

For what it’s worth, the whine gets louder when the motor is sending power to the rear wheels, but is present at almost any speed.

Hoping diff fluid solves it. If not I’ll be hoping for wheel bearings. Not particularly excited about replacing the diff or center support bearing.
 
I just did a center support bearing. It took me a couple tries with different dies/punches and the hydraulic press. When I say dies/punches I mean pipes, sockets, and whatever was laying around. I broke the first rubber support. I had a couple more new ones on hand, so no big deal. Just pay attention to the depth of the bearing and where the dust shields go.

If you went low on fluid you could have toasted the gears or bearings. Excessive backlash in the gears will cause whining.
 
I use a giant syringe-like tool to inject new fluid into differentials. The job is so much easier that way vs. trying to squirt it in with the bottle/hoses/etc.
 
Update: Drained the old oil today. It was black and sludgy. There were some metal shavings on the magnet but nothing crazy.

Replaced the oil. Took it for a spin. Same whine/whirr sound. Bummer.

Any tips on differentiating issues with the center support bearing vs the diff?

Axle looked pretty rusty and tired when I was under there. Should I just be looking at replacing it instead of replacing the diff?
 
First off, do the differential yoke twist to check for play in the differential. If you can twist the yoke at all without any movement in the rear wheels you have lash inside the differential that is not going to go away with an oil change. The fact that the noise changes under load versus coasting is consistent with a differential problem. If you do a Google search on diagnosing differential problems by noise you can find more details.

Complete diagnosis requires inspection and measurement. Replacement of parts requires removal of the guts. On the early Dana 30 this requires a case spreader and I expect that yours is likely the same. Although people have managed to remove the guts on the Dana 30 without the case spreader, it is not advisable.
 
Your whine is more likely to be wheel bearings and/or driveshaft carrier than ring and pinion. It takes a lot of abuse to get them that bad.
 
There is a # etched on the ring gear for the back lash, some where between .005 to .008". .001 shift reduces back lash by .001" approx. When I rebuilt the diff for my MG Midget, back lash was .029, It would howl @ 55-60 MPH. I was able to switch shims side to side, I was lucky, now it is quiet. Things wear out. My V8 Wagon is suffering the same fate, @ 60 MPH I can hear some whine, But [1031/3,31 gears] I have driven it hard since 2008.
 
when the ring and pinion wear threw the hardened surface, you will get whining noise. I had a worn out 9 inch dif years ago that would whine real loud during acceleration. Hope you get it figured out.
 
Update: Put in a rear end with a better diff from the junkyard in today. 10 hours of a whole lotta rusty hardware, but problem solved. Relieved.

Next... bushings.

Thanks for the help, y’all.
 
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