Cold High Pitch Whine from engine area... - BMW Forum

441tech · 12-10-2009, 02:28 PM

I'm hoping someone else has had this problem...

I have a '99 323i E46 Sedan (M52 motor) Automatic. The car & trans. have 180,000 on the ticker, and the motor maybe has 110,000. When it's cold out (pretty much all the time now), as I accelerate through the gears (in D)there is a high pitch whining noise that seems to be coming from the engine compartment. It will slowly die off and go away as the car gets warmer. It really sounds very similar to a power steering pump that ran dry. If it's really cold, it doesn't seem to fully go away. The noise also changes directly with engine RPM, although I tried a free-rev once out of gear, and it didn't seem to do it, although after I put it back in gear and took off, the noise wasn't there anymore either. It's loudest under acceleration, quietist when I let off the gas.

The trans. shifts fine. (Although a little jerky until it warms up). No lights on in dash, engine runs fantastic. Full synthetic 5W-30 changed religously every 5,000 miles. The viscous fan is not siezed. No coolant leaks. The power steering system doesn't leak a drop, and the noise has absolutely no change when I turn the wheel (going around corners).

Could this be pulleys? Belts? Water Pump? Trans?

Any help/input would be GREATLY appreciated.

marti5 · 12-11-2009, 03:06 AM

It maybe your rear differential whining, the sound will be transmitted to the front of the car and the noise of a diff will go up and down with revs. Also with that sort of mileage when was the last time the trans had a fluid and filter change.

brettski · 12-11-2009, 05:15 AM

One way to isolate the diff is to get up to speed and slip into neutral/foor off the throttle, then listen for a change in the pitch. Given that you think its related to the revs, I'd be more inclined to think that its further up the drive train, into the gearbox or engine, or maybe the altenator/water pump/belt tensioner. Could it be an intake leak, or maybe some kind soul has installed a turbo when you weren't looking. Bless their hearts.

marti5 · 12-11-2009, 06:10 AM

Quote:

Originally Posted by brettski

One way to isolate the diff is to get up to speed and slip into neutral/foor off the throttle, then listen for a change in the pitch..

Not a good Idea in an automatic....

441tech · 12-11-2009, 07:19 AM

Thanks for the advice. Although I forgot to mention that I also replaced the rear end a few months ago with a 30,000 mile unit. Plus, before I put it in, I drained the fluid that was in it and refilled with Redline.

That being said, when I started the car this morning, I noticed that it was making a bit more racket than before at idle. I rolled down the window, and it kind of sounded like it was pulleys or something...I had to get to work, so I'm going to check it out over the weekend, and I'll keep this thread updated. Hopefully it's nothing serious.

Thanks again.

marti5 · 12-11-2009, 10:55 AM

Hmmmmm.....Im now thinking its the torque converter on its way out.

441tech · 12-11-2009, 06:11 PM

Quote:

Originally Posted by marti5

Hmmmmm.....Im now thinking its the torque converter on its way out.

Why do you say that?

brettski · 12-11-2009, 09:49 PM

Quote:

Originally Posted by marti5

Not a good Idea in an automatic....

Why is going to neutral whilst moving an issue with these gearboxs?

I have done this plenty of times in other cars, without any issues. I am not suggesting going Drive to Park whilst moving, but Drive - Neutral - Drive shouldn't be an issue unless there is something different about the way BMW configure their autos. If there is an issue please let me know because I'd like to be aware of it.