Name that whine!

[Ferret]

Okay guys, gonna need a hand with this one...

While sat in the drivers seat, I can hear a whine coming from behind me while the car is in overrun.

Decelerating anywhere over 20 mph and I get a drive train whine.

I'm not sure where this is coming from... as when I sit in the rear seat while someone else is driving, I cant hear the whine noise.

My first instinct is to point a finger at the differential, but I'm not 100% and dont want to go throwing money at a rebuild without knowing first. Can anyone recommend a fluid to change into it to see if it'll shut the hell up?

These differentials have an incredible ratio on them, it's barely ticking over at 70mph in top gear, as the diesel torque allows it to really fly. I could try swapping a 540i diff into it as it's the closest ratio I'm going to be able to find , and see if it goes quiet under there...

However the rear suspension cage on the diesels is weird, it doesnt have any of the under-diff ladder frame in place :(

EDIT: Anyone had any experience bearing changing/rebuilding a diff?

[Morgenster]

Okay guys, gonna need a hand with this one...

While sat in the drivers seat, I can hear a whine coming from behind me while the car is in overrun.

Decelerating anywhere over 20 mph and I get a drive train whine.



Define 'overrun'?
Sure it's not wheelbearings? My old E30 had a bad wheelbearing which would get real loud at speed. lifting the rear with transmission in neutral and turning each rear wheel can tell you what's up. Have someone hold a wheel and then turn the other. Makes it easier to locate noises and excessive friction. Just be careful with the front wheels. They need to be firmly fixed, though something tells me you of all people should know all this?

[Ross]

If overrun is off throttle, coasting then I agree with you pointing to the rearend. Not the diff but the ring and pinion. Put some fresh oil in there and see if things improve.
Lots of miles?

[Barney Paull-Edwards]

EDIT: Anyone had any experience bearing changing/rebuilding a diff?[/QUOTE]
Dont drop the oil all out,add some Wynns and see if it goes.I have spare 535 diff so you are welcome to swap, leave me the original and I`ll do the bearings,do not have tolerances but cannot be too tricky, done toyota, Range-Rovers and all three of Metro`s(two bloody times!),bought engineers blue in bulk for that one.Does yours have an LSD, if so remember they use different oil and Wynns will piss it off.

[whiskychaser]

Jack up the front end. Grab the tyre at 12 and 6 o/clock and wiggle. Yes 2inches is small but a bit too much for a bearing

Edit: Must have been replying to another thread or need more water with it. But I DO know what over-run is:-)

[632 Regal]

Been there done that...

http://www.bimmer.info/~regal632/rearend.html


Anyone had any experience bearing changing/rebuilding a diff?

[Ross]

Hey Jeff, I have the same press you do!

[Barney Paull-Edwards]

Been there done that...

http://www.bimmer.info/~regal632/rearend.html
Anybody who praises Smokey Yunick is a God themselves! His variable displacement V8 is in a museum near here, now that man defined lateral thinking, or downright sneaky!

[Ferret]

Anybody who praises Smokey Yunick is a God themselves! His variable displacement V8 is in a museum near here, now that man defined lateral thinking, or downright sneaky!

Okay guys, I'm now more starting to think it's the centre bearing and/or a universal joint...

After having crawled all over the back of the car while the wife was driving, I was starting to get confused. While sat in the back seat, you can hardly hear the noise at all - and it felt like it was coming from in front slightly.

While sat in the drivers seat it definitely sounds like it's coming from behind you.

A few days on and there's a metallic hissing noise coming from under the rear seats which is making me think that the mechanic who changed the Guibo didnt re pre-load the centre bearing and after the abuse it was put through while the guibo was deadded, the bearing and/or the nearest uj is now packing in...

Any thoughts on this guys?

[Ross]

That hissing sound you descibe makes me think pinion bearing. If it doesn't change between load and coast then look to the bearing.

[SnakeyesTx]

My first guess would be pinion bearing as well. How many miles do you have on that diff?

Usually center support bearings would make a noise just about any time, on the throttle or coasting (probably more prominent when coasting). If you happen to use an additive like Lucas oil treatment for the diff and the noise goes away, keep in mind you're only prolonging the inevidable. Another way you could probably check without getting too dirty is to disconnect the driveshaft and grab the pinion yoke and see if there's any excessive slack in-and-out or side-to-side.

[Ferret]

My first guess would be pinion bearing as well. How many miles do you have on that diff?

Usually center support bearings would make a noise just about any time, on the throttle or coasting (probably more prominent when coasting). If you happen to use an additive like Lucas oil treatment for the diff and the noise goes away, keep in mind you're only prolonging the inevidable. Another way you could probably check without getting too dirty is to disconnect the driveshaft and grab the pinion yoke and see if there's any excessive slack in-and-out or side-to-side.

The Diff has just gone through 140k...

I'm going to get under the car... well it was going to be this weekend but I've just been informed i'm working for the 6th weekend in a row. *Really Pissed off now* ... and check for play in the system. I might drop the exhaust and have a look at the condition of the centre bearing - see how rough it is.

I'll set the tranny to neutral and try and turn the whole lot over by hand to see what condition it's in. Theoretically I should be able to feel where the busted bearing is.

I'm seriously considering selling the bugger quick before the whine gets really noticable and buy that nice M badged 535i down the road...

What oil do you guys recommend for an LSD housing?

[Dave M]

The Diff has just gone through 140k...

I'm going to get under the car... well it was going to be this weekend but I've just been informed i'm working for the 6th weekend in a row. *Really Pissed off now* ... and check for play in the system. I might drop the exhaust and have a look at the condition of the centre bearing - see how rough it is.

I'll set the tranny to neutral and try and turn the whole lot over by hand to see what condition it's in. Theoretically I should be able to feel where the busted bearing is.

I'm seriously considering selling the bugger quick before the whine gets really noticable and buy that nice M badged 535i down the road...

What oil do you guys recommend for an LSD housing?

All good ideas, except for the last (M-badges 535 ;) ). Now, it can't be that difficult to find the source of the 'whine'.

First, you won't be able to feel a bad center bearing as turning the driveshaft is a fruitless endevour. Until you drop the driveshaft, a visual inspection is more likely to tell you something.

But, before you go dropping the exhaust, find a lift (I know, I know) or get some very sturdy jack stands and a helper and raise the rear end. First turn the wheels in neutral, if nothing, start it up, slide it in gear and very safely have a listen for the noise.

FWIW, my diff has gone through 300+k and doesn't make a peep. I would hope its your center bearing which is a relatively easy fix.

Dave M