Member
Good morning, I'm restoring mine 850i of 1991, manual transmission.
It has a vibration between 1500 and 2500 rpm.
The vibration is perceived in the passenger compartment and seems to originate from the floor; it also propagates in the seat.
The vibration is present both with hot and cold engine, both in neutral and during driving.
I replaced the engine mounts (one crushed and the other torn), belt, belt tensioner, and water pump (which had the shaft misaligned and made the fan swing)
The vibration has been reduced by 80%, but it is still present.
The fan clutch and the fan itself have not been replaced .... The residual vibration could be due to a deformation of the fan clutch that for several kilometers has rotated irregularly?
Could it be the flywheel or the clutch?
Could it be a problem of injectors and compression?
Or what else?
P. S. Another symptom: downshifting, at the release of the clutch, the gear change tugging.
Help me
Thanks
Member
I would removed both drive belts and start vehicle on cold, and see if it'll still be present. (note: since belt will be off, make sure don't run your engine too long, since your water pump won't be rotating - 10-15 seconds won't hurt you engine without water pump or alternator)Originally Posted by MarcusP8
What you mean by Tugging?
Ultimate Machine Driver
Check Transmission mounts and double check that the engine mounts weren't torn.
Member
a
The both engine mounts have been replaced.
The vibration has been reduced
But now I think the vibration may be due to a resonance phenomenon of the collector or Catalyst.
The previous owner had replaced them with non-original steel products.
If not well fixed could they touch the frame, resonate and propagate the vibration? Only in a specific range of rpm?
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