Hi all, recently, I've noticed a whine that tends to come and go while driving my brick. Sometimes it's really noticeable, other times, not at all. It's not really high pitched, like a belt squeal or brake squeal, but it's not really a groan or a grind either. The pitch raises with the speed of the car, and drops as I slow down. At steady speed, the pitch is steady. My best attempt at writing what it sounds like is that it sounds alot like a fire station siren, or a tornado siren, slowly ramps up with acceleration, holds steady, then slowly drops as I come to a stop. It seems like maybe it's coming from somewhere central to the car, like the driveshaft, or the differential, because if I drive with my windows down and go near a building it doesn't seem to be more prominent on one side or the other. I uderstand this is not the most exact method of troubleshooting. It is definitely not related to engine RPM. I'm thinking it's one of three things.

1) Drive shaft support bearing. I slid as far under the car as I could yesterday when I got home from work (after dealing with it the whole trip) and the bearing didn't feel warm at all. Would it if the bearing was going?

2) The rear end has an issue.

3) New tires that I recently put on the car, though I would think that it would happen all the time and not come and go like it does.

High-pitched whine IME is carrier bearing. I service mine on the car. Several threads in the archives.
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240 drivers / parts cars - JH, Ohio

Similar sound on my '88 244 turned out to be a loose brake pad shim plate. One of the holes in the plate that the retaining pin goes through had rusted out.

It was pretty clear to me the sound was coming from wheel rotation and from the right front.

I know it's not the shims. Up until this past weekend, I had no shims on the car. Thanks for the tip though.

I went through the same thing trying to find the same noise on my car. I thought it was the trans for a while until I put in a new engine and trans and didn't get rid of the noise! I got worried it was the rear end, so I jacked up the rear and put jackstands under the rear jacking points. I started the car and put it in drive. With the hood up, I SLOWLY revved up the engine and let the trans shift up a few gears. The noise was loud and obvious! With the driveline spinning down, I poked my head under the car and verified that it was the driveshaft carrier bearing.

If you're going to try this, I HIGHLY suggest using four wheel chocks to tightly chock the front wheels. Also, be careful to rev slowly! You'll be surprised at how much the car wants to rock back and forth, even when on very stable jackstands, when the mass of those wheels accelerates!

I just changed my carrier bearing assy this past weekend. It's not a hard job. The driveshaft came apart easily, but the bearing didn't want to come off of the driveshaft. I had to get a bearing puller set from Harbor Freight - that did the trick! I cleaned up the bearing surface on the front driveshaft with some 400grit wet/dry paper and put the new bearing in the oven for 15min at 350deg. The new bearing just literally fell into place. When it cooled, it was solidly attached. If you're going to do the job, also be sure to mark the driveshaft positions to the trans and the diff. Align the front and rear driveshaft yokes per your Bentley manual when matching the splines. Easy job!

Steve

Thanks to all. I don't know why but the sound went away shortly after I posted this and has not returned. I did have a leaky steering rack that I used stop leak to correct about the same time. No more leaks or noise. Not sure if they were related or not..

Does it by any chance sound like a car backing up with Straight-cut gears?

I have no problem using WD-40 as a light lube and it's always served me well, but I think a heavier grease would be a good idea if that turns out to be the problem.

Does anything in particular make you suspect the rear end?

Might the tires whine only when they're warm or cold? You could raise or lower the pressure a few pounds temporarily and see if it changes the pitch at all.

You might also check for something rubbing on the driveshaft. It's not obvious, but it might happen. Also, is this a manual or auto trans car?

Good Luck
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1990 740 Turbo, on its way to stock specs, maybe beyond

We used to have the same issue when we had the kids--whined from start to finish-now it's the mother-in-law---. I keep telling my wife duct tape will correct that---. forgive me-----

To isolate the center support bearing and possibly rule it out I would recommend you do something very simple: Get under the car and squirt WD40 on the bearing from BOTH front and rear. Then drive. If the whine goes away.... If not go for the other stuff. I know people cringe when WD40 is mentioned but it worked for me. In fact, in cold, damp weather [such as it is here in Scam Diego CA] periodically the whine returns in my car and I get out the WD40 and am good for another season, never have changed that bearing.

i had a similar problem in one of my 240s. i would suspect the carrier barring as well. i live in new england, and the problem was much more noticeable when it was cold out. in fact, during the summer i never even heard it.

Carrier bearing would be my pick. Drop it, pup the seal, clean, regrease.

Whines can come from several things of course but carrier bearing is the most common IME.
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240s: 2 drivers and some parts cars

I am having the same problem I sounds like a small turbine and I here it the most comming to a stop from 40 to 5 mph I am jacking it up this morning to see if I can get it to do it while the wheels are off the ground and ss if I can pinpoint where the noise is comming from. I am thinking transmission. 92 240

I am having the same problem I sounds like a small turbine and I here it the most comming to a stop from 40 to 5 mph I am jacking it up this morning to see if I can get it to do it while the wheels are off the ground and ss if I can pinpoint where the noise is comming from. I am thinking transmission. 92 240