In the last 2 weeks my 1990 volvo 240 DL (315,000 km) has developed a soft grinding noise in the rear right wheel area. If you're from a snowy area, it sort of sounds like tires crunching over cold snow.

Testing
- happens on snow/off snow/on pavement. It has nothing to do with the driving surface
- happens during acceleration/coasting/braking. Pretty much all the time.
- happens in drive and in neutral.
- sounds cyclical
- visual inspection of rotors & pads (disc brakes in rear). All looks fine.
- no abnormal tire wear patterns

-> During my testing I drove several hundred meters in Reverse, at speeds up to 30-50 km/h. This seems to 'reset' something and the noise stops. It will be silent, even in Forward for the next few minutes before starting up again.

It's about -25 C outside so I haven't pulled the wheel hub off yet, but my gut is thinking wheel bearing. Could it be anything else? How difficult is it to change the wheel bearing on a RWD system?

 

Pull the parking brake while you're rolling and listen for a change in sound. I would suspect the parking brake shoes. Jack it up and spin and shake the wheel.
Still, you need to pull the wheel off to check the pads, caliper and shoes to see what you've got.
Ed

 

No change in sound with the ebrake. I've got rear wheel disc brakes and there is good play in the cable. It's not locked down and the rear wheel assembly is loose enough to spin with force by hand when out of gear.

 

does the noise change if you lightly ride the brake pedal?

oh hey, do you have the bazillion spoke "Corona" wheels, with the stainless steel flying saucer center cover? those are notorious for rattling in a tinny kind of way that might be mistaken for this crunchy sound you're hearing.



try taking that cap off and driving...


p.s. *ALL* 240's have 4-wheel disk brakes, but the parking brake is a little drum brake on the inside of the rotor disk.

 

May have a pebble stuck in there somewhere...

 

No I just have standard steel rims, nothing fancy to rattle about. Also no change if lightly riding the gas or brake pedal. This is a loud grinding/crunching sound in any gear or neutral. Almost feels like its travelling through the whole body.

Didn't know about the mini drum ebrake though. I've never looked at it in detail but thought it was the cable spring pressure system on the pads-type. could it be stuck on?

When im in neutral on a level surface and shift into drive, i immediately start rolling. When I pull the parking brake, I stop. When i release the parking brake (still in drive), I start rolling forward again.
Immediately. I would think that the parking brake is not stuck on.

 

hmmm. I think I'd jack up the back wheels and spin them by hand (with the car in neutral and parking brake released) and see if you can hear/feel said noise. could be something as simple as a pebble like lev says stuck between the shield and brake rotor.

or, I suppose it could be a wheel bearing going, or even the differential. the differentials on these cars are tough as nails, but if they have ever run dry or something, then all bets are off.

 

Jacked up the rear end and spun the wheels out of gear. No sounds and no grinding. Even threw the car in drive and let the wheels spin slowly... no resistance or sounds encountered. Seems that it only happens when under load.

I'm not sure about the history of the differential. I've only had the car < 2 yrs and didn't get a good history from the previous owner. Sounds like this could be a bit of a job...

 

maybe try this? get someone to test drive for you, find a big empty parking lot in a quiet area, and a bicycle... follow them around on the bike and see if you can pinpoint where its coming from.

of course, winnipeg in the winter, this may not be very practical

 

hehe yeah it's not the greatest time of year for a bikeride. But I did try something similar the other day. I had my wife drive around the parking lot and I jogged alongside. Very hard to pinpoint the source.

BUT I think your comment about the differential may yield something. I was so scopelocked on brakes/wheel bearing when I had it up the other day that I didn't check the differential. Just took a peak with a flashlight and it is dripped wet with fluid. Looks like I may be running low/empty and it would explain the grinding.

I'll take a look again tomorrow when the sun's out and it's a bit warmer... maybe take a picture or two if my hands will stand the cold.

 

a happy rear end should look like this (except without the shiny new IPD sway bar or overload springs, hah!)


click for bigger...

 

Update: Well, slight improvement.

We've had some warmer weather (-10C ish) in the last few days. I took advantage of it and yesterday drained the oil in the differential... if you want to call it oil. It was black as night and about the consistency of warm tar. Slightly low...maybe 70%. But definitely not as low as I had thought/hoped.

Seems like the differential case is leaking. Maybe around the pinion seal... but it's so gunked up I can't tell at this point. I was hoping that there would be no oil inside and that would be the cause of the noise.

I replaced it all with a Motomaster Synthetic 75W-90 gear oil. I still get the crunching and grinding noises, but after I've driven 5 or 10 km they seem to ease up and stop. Then again, it could just be the warmer weather in general is helping.

Now I'm wondering if something went in the differential and perhaps the pinion needs to be adjusted?

 

Did you ever find the grinding issue?

My 92 wagon also has an issue that comes and goes. It grinds for a while and then is completely smooth most of the time. Mostly cold weather and when starting out. It sounds like the disk dust shield might be involved.

 

My grinding started Feb 2014 and quit when the weather warmed up until it started again in Nov 2015 and quit again this spring when the weather warmed up. The brakes look good, the parking brake works. I thought maybe there was ice in the differential? Checked the drain and no sign of water. So it only grinds for a 1/4 mile or so in the winter and then stops for the rest of the trip and doesn't make any noise at all in the summer. I'm told that wheel bearings don't get better, just continually worse. It is a hideous noise, sounds like something heavy dragging and its coming from the right rear wheel. The first time it happened I stopped and looked under the car and found nothing and when I drove off again it was quiet as could be.

 

Disassemble and inspect.

 

Did anybody ever figure out what the grinding noise was?