Engine Noises at 3000-4000 RPM when cold

0

Question:

My 73tii has recently developed a noise that sounds like something vibrating, and happens between 3000 and 4000 rpm’s when cold. From the driver’s seat, the sounds seems to come from just beyond the firewall, and down around the transmission. Once warmed up, the noise goes away. Any ideas on what this might be? As far as I know the engine has not been rebuilt, and is probably pretty tired. Timing chain noise? Piston slap?

Thanks, Dave

Answer:

We have some recommendations, but we can’t be for sure on this one. If you have access to a lift, you may be able to pinpoint it yourself. An experienced BMW mechanic could probably pinpoint it with a stethescope on a lift.

Noises in the region you are speaking of could be:

  • Your transmission throw out bearing could be making the noise, try holding the clutch in, does it go away?
  • How old is the starter? The starter pinion clutch may be worn out and slipping out onto the flywheel gears and making contact at high RPM. This happened to me before and it was an awful vibrating racket near the firewall, and could be heard easily.

Back to your original comments:

  • The timing chain is at the front of the engine, not the rear. The timing chain noise is more of a “grrrrrrr”, and can be adjusted. See our other how to on that one:

Noisy Timing Chain: How to bleed your M10

  • The oil pump’s chain is up front also, they usually don’t make noise, they just quietly go bad.
  • In general, wrist pin noise is more of a ratcheting sound and not a vibration and does not go away when warmed up.

Last update: 2009-06-24 19:02
Author: tiiregister

Leave a Comment