boxerfan

I recall this conversation from some time ago. Somebody reported that the pulley on different brands sounded very different when tapped. I don't recall the recommendation as far as Graf or Hepu.

I think Frank may be onto something as well. A tighter belt will transmit differnt vibrational frequencies into the system. It may be that a tighter belt causes the lighter pulley to resonate and cause the warble.

RussB

My car: 1988 5000CSTQ

Last I knew, Worldpac sells both Graf (or Geba) and GMB pumps. The GMB is slightly more expensive. I installed a GMB during the last timing belt change with no particular attention to belt tension, and it's quiet.

Here's my observation:<ul><li><a href="https://forums.audiworld.com/v8/msgs/64434.phtml">https://forums.audiworld.com/v8/msgs/64434.phtml</a</li></ul>

Chad T

I was reading your old thread last night Russ. Some interesting observations. Looks like I'll have to see if I can find me a GMB pump. Might try adjusting the TB tension if it's gotten loose for some reason.

Not a huge deal other than the noise which could also be described as a sort of a dolphin bark. I knew I was reading about the same thing when I read about the turkey gobble though. ;-)