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Matt
Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 20616
Experience:  BEng hons Mech engineering, in auto industry 22 years
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My BMW e90 320d makes a noise when rev it over 3 n half rev

Customer Question

My BMW e90 320d makes a noise when rev it over 3 n half rev some thing rattles
Submitted: 2 years ago.
Category: BMW
Expert:  Shantal-Mod replied 2 years ago.
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Expert:  Matt replied 2 years ago.


Hello

if there's a 'tinkling ' noise at idle as well as the rattle over 3.5K rpm then I'd agree that it could be a timing chain

for a turbo to rattle then it would be badly damaged and you can check it over by removing the high pressure intake hose after the turbo and have a feel of the turbine wheel - there should be no play radially at all - but a little bit of axial / end to end float is normal


I'd also try removing the auxiliary drive belt and turning every pulley and ancillary ( power steering pump , alternator etc) by hand. All should turn easily (with the exception of the AC pump) with no grittyness or wobbly pulleys- If you do find a sticky pump / alternator then it should be replaced or repaired
If the engine is stone cold you can briefly run it with no belts to see if the noise changes or has gone away, this will help show if an ancillary is the issue

Examine carefully the condition of the bottom / crank pulley as these are composite construction with a rubber element and its possible this rubber is breaking up and allowing the two metal portions to move.

Another possibility is the variable valve timing system as this does rely on oil pressure to correctly synchronise your vvti pulley on the end of the camshaft. If the valve has become blocked up then its possible the pulley is rattling about and producing the noise.

If all of this is OK then its possible the issue is with the dual mass flywheel on the other end of the engine, these are constructed in the same way I mentioned for the front pulley but are more prone to problems due to greater heat and larger forces.

If your gearstick is rattling this is another pointer to this being the problem.

Expert:  Matt replied 2 years ago.
Hi

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