240 Scraping noise from rear

I bought a 1983 245 a month ago in California, and I drove it back to Minnesota. Somewhere in Iowa, when leaving a gas station, I heard this loud scraping, grinding noise, from the rear of the car?it sounded to me at first like a brake was binding. No brake smell, though, and as soon as I accelerated past 30mph, the noise was gone.

It didn't come back until I left Chicago, some 800 miles later, also at a low speed. Then it dissipated and I drove the 400 miles to Minneapolis without incident.

I'm posting here because I've seen a handful of threads describing this same problem, none of which have been solved. The noise would occur every time I drove the car (i.e., every time it warmed up), for a few minutes, and then would go away if I kept driving.

The noise definitely tracks rotation of the wheels, and happens whether or not I am in gear. At low speeds, it almost sounded like my dad's Karmann Ghia did when it needed a new axle shaft IIRC (periodic clunk/scrape with each wheel rotation).

It seemed to be getting worse (heard it when going 65 one day), but then it went away completely. I heard it once for about 10 seconds a week later. I decided that it must have been the handbrake pads having worn out entirely, so elected to have them replaced. The handbrake was worn and at its full adjustment, but it wasn't the source of the grinding.

So now, I have a new handbrake, and no grinding to diagnose, but I'm paranoid that there may be an issue with the differential, or something else.

Most notably, it's finally gotten tolerably warm here in MN?and others reporting this issue had claimed it went away for months at a time when it was warm outside. What could that imply?

Thanks in advance for any suggestions. I know it's kind of impossible to truly diagnose, but I had to ask just to see if anyone had solved this obscure problem.

I mean this could be so many things. But also... there isn't that much that can REALLY go wrong?

I've found those IR temp guns ($15 amazon) work well in diagnosing any sort of dragging brakes because I can go for a drive and then shoot the temps of my rotors or hubs or whatever to see if one side is higher than the other side.

If you're worried about the diff, then I suppose it doesn't hurt to pull the fluid and get some fresh oil in there... see what's what. It can also be your driveshaft center bearing or a wheel bearing that has run dry of grease. Repair or replace as necessary.

Additionally the REAR bushing on the rear trailing arms (which are a pain to change) can have quite a bit of slop in them that can allow your axle to shift and possibly put some stress somewhere that goes away after it moves about.

It may have a sticking caliper, you should get the brakes checked out if you don't know how to do it yourself.

A couple of years ago to my amazement. My friends 1990 245 developed a scraping noise from the rear of the car that went away as you got over 30mph or so. If you drove around slowly you heard it all the time. It turned out to be his left rear wheel bearing was bad. Usually, they make a rumble or whining sound in my experience. But this one made a scraping noise somehow. I suggest you always replace both rear bearings if one is bad.

Thanks, everyone, for the replies! I did wonder whether a wheel bearing could be at fault—it seems to be the left rear wheel, and turning left or right would sometimes silence the noise for some time.

It's just entirely bizarre to me that the noise all but went away. However, with caliper in mind, I recalled that the car does pull a bit to the left. So that just might be the culprit.

I will find a way to flush and replenish the diff fluid, and check out the caliper. I still need to get my Bentley manual for this thing. If the caliper was sticking, I imagine that I'd be able to notice that friction rotating that wheel while on jack stands? I'm an absolute novice mechanic with anything other than air cooled VWs (with which I'm a ... more experienced novice).

In the meantime, I have driven probably 100 miles noise-free, but wanted to check in case anyone had witnessed this bizarre case, so that I have some plans for diagnosis next time I hear it.

I'll report back when it comes back and/or I find a definite culprit.

gdea73 said:

Thanks, everyone, for the replies! I did wonder whether a wheel bearing could be at fault—it seems to be the left rear wheel, and turning left or right would sometimes silence the noise for some time.

It's just entirely bizarre to me that the noise all but went away. However, with caliper in mind, I recalled that the car does pull a bit to the left. So that just might be the culprit.

I will find a way to flush and replenish the diff fluid, and check out the caliper. I still need to get my Bentley manual for this thing. If the caliper was sticking, I imagine that I'd be able to notice that friction rotating that wheel while on jack stands? I'm an absolute novice mechanic with anything other than air cooled VWs (with which I'm a ... more experienced novice).

In the meantime, I have driven probably 100 miles noise-free, but wanted to check in case anyone had witnessed this bizarre case, so that I have some plans for diagnosis next time I hear it.

I'll report back when it comes back and/or I find a definite culprit.

Click to expand...

I've had good luck replenishing fluid using this method.

I have an occasional scraping sound at low speeds so will have to check out some of the suggestions here too.

I had a higher pitched grinding for a while and could not find it, until there was a bad vibration/grinding noise under 25/30 mph, turns out my center bearing was shot along with mount, plus my center u joint froze causing everything to rattle like crazy at low speeds. 740 tho, should be similar, right?

Noise would wait a couple miles from cold to start, checked all brakes and wheel bearings, all were good. Got louder with tire speed and didnt go away until under 10 mph. When the u joint froze, it was a lot worse and could feel the wobble up to around 30 or so then after that just a metal grinding noise

Mbeas96 said:

I had a higher pitched grinding for a while and could not find it, until there was a bad vibration/grinding noise under 25/30 mph, turns out my center bearing was shot along with mount, plus my center u joint froze causing everything to rattle like crazy at low speeds. 740 tho, should be similar, right?

Noise would wait a couple miles from cold to start, checked all brakes and wheel bearings, all were good. Got louder with tire speed and didnt go away until under 10 mph. When the u joint froze, it was a lot worse and could feel the wobble up to around 30 or so then after that just a metal grinding noise

Click to expand...

That's interesting, because it is quite similar to this issue in the times that it occurs, except that currently I have no noise at all and I think I attribute it to warm weather. Also, it's hard to effectively describe a noise, but I actually don't believe I felt any vibration along with it, and it was not high pitched. For those of you that also experience inclement winters, it sounds sort of like driving over a particularly snowy or icy patch of highway, in fact when it first occurred I thought that was what had happened.

Still need to get new diff fluid in there (have been focusing on my Karmann Ghia lately). Thanks, Rusty_ratchet, for linking that method.

Update: car was quiet all summer. Noise returned the first frosty morning of the season a couple weeks ago, and is as before present once or twice per drive if the ambient temp is cold enough.

Diff oil still looks practically new. No metal shavings or anything. Pulled on wheels: no noticeable play due to wheel bearings. It may be an issue with the axle shaft as it meets the diff, but I don't really know.

It's my daily, so I'm just going to keep driving it until it breaks, then evaluate crushing versus replacing the axle.

The linings on the parking brake shoes of my 88 765 had came off and made so much noise that I had to pull into shopping center and pull the rotor to investigate. I found the linings from both parking brake shoes on the drivers side had came loose from their backings. Threw the linings away and put the rotor back on. I have never used the parking brake on this car and maybe that is why the linings separated.

In reference to my post #4 above. My friends car had no play in the rear wheel bearings and the horrible sound had only started when it got to the first really deep freeze of the winter. It's the only bad bearing I've ever heard a srape sound from.

dl242gt said:

In reference to my post #4 above. My friends car had no play in the rear wheel bearings and the horrible sound had only started when it got to the first really deep freeze of the winter. It's the only bad bearing I've ever heard a srape sound from.

Click to expand...

Thanks for pointing that out. Perhaps I do need to reinvestigate this potential cause, especially since I recently noticed that the noise goes away if I take a left turn, but stays the same or gets louder during right turns. That could point to the left rear bearing.

Hope it helps figure out the weird stuff like that. Sometimes the improbable is what the problem is.

gdea73 said:

the noise goes away if I take a left turn, but stays the same or gets louder during right turns. That could point to the left rear bearing.

Click to expand...

That is important info. I would just add that from inside the car it is possible to mistake where a sound is really coming from. I would suggest checking your front wheel bearings. It is easier than checking the rear, and the fronts fail more often.

Two weekends ago, I had this exact same problem.

Checked the brakes, they were good.

Took the RR axle out and found that the axle bearing race was trashed in one spot.

Put in an axle from a parts axle that I had and all was well.

quillc said:

Two weekends ago, I had this exact same problem.

Checked the brakes, they were good.

Took the RR axle out and found that the axle bearing race was trashed in one spot.

Put in an axle from a parts axle that I had and all was well.

Click to expand...

That sounds about right. Somehow I feel that this is more likely the cause of my issue than the bearing, but putting a new half axle would cover both. Now my dilemma is to determine which side, and also, to find a parts axle. I have access to an '83 244 for parts, but it has been sitting for years, and I don't know if its rear axle is in good working order.

Had similar low speed nose, but more constant from a spring in center mount rubber failed and grinding on everything there.

gdea73 said:

That sounds about right. Somehow I feel that this is more likely the cause of my issue than the bearing, but putting a new half axle would cover both. Now my dilemma is to determine which side, and also, to find a parts axle. I have access to an '83 244 for parts, but it has been sitting for years, and I don't know if its rear axle is in good working order.

Click to expand...

Its probably good. The axles aren't side specific, so you could use either one. Pull both and check the bearings.

In my case, it seemed like the noise was coming from the RR. That was in fact which side was bad. I pulled both to inspect.

You really need to pull the race to inspect it.