My car runs a 1990 turbo motor, and has a very strange engine noise that appears to be related to oil temperature (ie viscosity or how thick it is).

When the engine is cold, there is a noticeable whirring sound (sounds like a worn out diff), that goes up and down with engine revs. It can't be the driveline, cause it doesn't matter what gear, going or stopped, it's from the engine somewhere.

The hotter the oil gets, the quieter the noise becomes, so much so that after a good thrash you can't hear the noise. The motor runs really well, but it's just this weird noise. I changed the oil from Penrite HPr 40 to a lighter weight oil, and that has improved things... So the noise appears to be related to oil thickness (ie the thicker it is, the louder the noise).

Anyone have any idea what's going on???

Thanks!!

 

Rotor bearing?????

 

I don't think it's a bearing, as it gets quieter as the motor warms up - I think bearings usually get noisier as the oil thins.

Also, it hasn't gotten any worse, and it has been driven hard from time to time. I think it would have let go if it was a bearing. Could be wrong, though

 

check your post in the ausrotary forum