Trying to diagnose a rattling or grinding noise from engine, '98 Boxster 121K

I'm assuming it's an idler pulley. The top top one spins smoothly but the lower one and the tensioner have some noise, although not as much as I was anticipating. I should mention there is also a squeaking noise at around 2400 rpms.

All the accesories spin smoothly, it's hard to tell with the ac compressor unless it's clutched into the system.

Should I go ahead and replace the lower pulley and the tensioner?

Thanks.

Quote
worldwide4
I'm assuming it's an idler pulley. The top top one spins smoothly but the lower one and the tensioner have some noise, although not as much as I was anticipating. I should mention there is also a squeaking noise at around 2400 rpms.

All the accesories spin smoothly, it's hard to tell with the ac compressor unless it's clutched into the system.

Should I go ahead and replace the lower pulley and the tensioner?

Thanks.

cold and run a bit?

Be sure you note the routing of the belt before you take it off. Take pics.

If the noise is still present, well, come back with that bit of news.

Assuming as is almost always the case the noise is absent, then with the belt removed then you can replace the suspected idler rollers and tensioner. In fact IIRC -- I bought a full spare set years ago and still have them in the trunk -- the idlers/tensioner are not that expensive so you can replace them all, without incurring too big a financial hit.

Spinning smoothly is just part of the testing you should do. Does the belt have a sharp edge? This can be a sign the belt is not tracking right and this is due to (my experience) a bad water pump. Check every accessory drive pulley/shaft for any play. Go around several times until you have found one with a bit of wiggle or you can say no pulley/shaft assembly wiggles any more or less than the others.

I confirmed the water pump was bad doing the above.

Sincerely,

MarcW.