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Matt
Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 20605
Experience:  BEng hons Mech engineering, in auto industry 22 years
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E46 316 touring Occasional repetitive scraping noise form

Customer Question

E46 316 touring

Occasional repetitive scraping noise form gearbox area related to speed only .

Can be stopped sometime by reversing few times.

Also at end of period with no noise, sometimes a loud clunk noise from the diff near side when a very low speed . Scraping noise starts soon after.
Submitted: 2 years ago.
Category: BMW
Expert:  Matt replied 2 years ago.
Hello

I'd 1st try draining the diff oil off and as it drains use some paper towel to strain the oil to check for bits of metal

then replace with fresh oil

if that doesn't help then check over the state of the prop joints and centre bearing it should turn smoothly with no notchy action and the centre bearing mount have no splits in the rubber

Also check for worn mountings - check the tightness of the engine and gearbox mounts and their condition - this is best done by using a jack to take the weight of the engine off the mounts and seeing if any cracks or splits open up in the rubber.Also check the tightness of the mounts bolts


Customer: replied 2 years ago.

Might this cause it


Rear near side subframe mount cracked

Expert:  Matt replied 2 years ago.
Hello Graham

a cracked rear mount will certainly give issues with the diff location
So the load path through the joints and diff won't be right and potentially could result in the joint wearing prematurely

so I'd look into getting the cracked part welded up to see if that helps at all

if it does then consider replacing the rear subframe with a good used item
Customer: replied 2 years ago.

Thank you

Expert:  Matt replied 2 years ago.
no problem Graham

I'd alsocheck for a worn drive shaft joint - typically these won't produce any vibration unless badly damaged but they can be noisy or 'clonk' for a long time beforehand, take a look at the drive-shaft rubber boot there should be no rips or tears in it and the suspension should be clean and dry of any grease.

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