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[platty]

Hiya guys,

Car has been running fine but on Wednesday I pulled into work as usual and reversed into my space, only to hear a grinding noise coming from the front(ish) end of the car. Though it might just have been me reversing with too little revs and the diesel struggling.

Drove about 130 motorway miles not remembering the previous days problems, but when i got there i was hearing the same sound when turning right only. I jacked up the front left corner and had a good look around the suspension components, wishbones (knackered but being replaced, i do not think these are at fault), the steering felt good, the strut was tight and all seemed to be ok.

I drove home again and it seemed to be getting no worse.

This morning i start the car, and whilst it is still on choke, the noise is constant. If i rev the car it increases slightly but as the revs increase it stops. If i engage a forward gear and release the clutch slightly then it stops, if i try and reverse, the noise is extreme! When driving, under acceleration it is fine, drives just like normal - under deceleration the noise is bad and i can feel vibrations through the floor with my feet. The noise still happens on right hand turns, but not left hand. But when i brake firmly, the noise doesnt occur under this kind of deceleration...

I am starting to think that it is a drive train problem, possible prop shaft bearing? Car is parked up now as is undrivable - Any ideas would be greatly appreciated!

[Mick_600]

Hi, just to check does it only make a noise when the car is moving ?

If moving only, I would check front wheel bearings, probably one getting loose more than failing. The noise would be the disk scraping on the brake caliper when it moves. When you press the brakes, this will stabilise it a bit in relation to the caliper and the noise go away. Worth checking sooner rather than later well ...... 3 wheels on my wagon !!

If it occurs also when stopped, I would say either clutch related or input shaft.

[platty]

Originally I noticed it only when moving, but this morning it did it (for the first time) when i was stationary. It was a constant noise when idle (700rpm) when i revved it to about 1200 rpm the noise increased in speed as though something was rotating faster. After 1200rpm the noise disappears.

When driving forward accelerating in a straight line, there is no noise, vibration or anything to indicate there is a problem. Have checked both wheel bearings, checked callipers, discs, all suspension and seems to be unrelated to these as far as i can see.

I agree that it could be drive train related but why would it make noise when stationary and decelerating but not when accelerating?

It is baffling me somewhat!!

[hotel21]

If it happens when stationary and simply by revving engine then you can obviously rule out wishbones, bushes etc on suspension and wheels.

That leaves anything driven by aux belt so try again to replicate the noise with aux belt removed, if possible.  If noise goes, then something driven by belt.  If noise remains, something directly driven by engine.

If noise is there when driven by aux belt, try with aircon on/off and replicate again to try to tie down noise.....

[platty]

If i push the engine (rocker cover) from the right side of the car it makes the noise... engine mount? someone has told me that these bmw lumps have hydraulic engine mounts... is the true?

has anyone had a bmw lump out before and know what the mounts are lilke?

[ians]

Its nothing as simple as a loose heatshield at the front of the exhaust/manifold is it?  Could resonate at different (engine) speeds/loads..

[platty]

I'm pretty sure it is the engine mount now, just wondered if anyone knew about them.. I might have to start a new thread!

[platty]

Finally got around to looking at the strange noise - and i'm glad i did!! I suspected that the engine mounting could have failed and i wasn't far off the mark.
Removed the stupid plastic cover and jacked the engine up and saw this:



Don't worry about the oil.. leak sorted now



1 bolt missing, 1 finger tight and the other half way out... This had allowed the engine to drop on the near side by about 1 inch resulting in...



The pulley is munching into the anti roll bar and also spitting rubber everywhere.

Removed offending bracket, straightened and refitted to give proper clearance again..



Much better!!! Glad I had a look sooner rather than later, i think it could have lead to many more problems if left alone!!!

Belt is looking very much worse for wear so will have to change that before i use the car, pulley should be ok though.. opinions?

[GastronomicKleptomaniac]

I'd swap the pulley too, for the price of the part it saves having to get in there if it does fail. Nice job identifying it, though.