This is what a failing water pump on your 996 sounds like. Hopefully this will keep some folks from freaking out, thinking the rattle they hear is their IMS bearing.

P.S., If anyone knows where I can get a cheap 996 water pump, let me know! I don't have a whole lot of cash on hand at the moment (a new little girl was just added to the family ).

 

Video #2 also shows the angle of the water pump pulley changing - when you can see it rocking, you know its bearings are shot.

 

Nice. What's that white fan lying on the ground?

 

BTW, we should all upload sound track of our IMSBs so we can compare their health

 

I was just cooling the motor down a bit. Just got home from work and it was getting HOT lying under there poking around with my mechanic's stethoscope!

 

Absolutely. That's exactly what I was trying to show in that video.

 

Go for the Pierburg brand, KO performance had good pricing http://www.koperformance.com/catalog...ater-Pump.html, you may also want to try 928s R us http://s287999742.e-shop.info/ Roger Tyson is a great supporter of the 928 community but can also get other Porsche parts at good price.

 

Thank you!

 

Don't forget to make a vid for us after the new water pump is in the car. So we can compare the sounds. I mean are you really sure that is where the knocking sound is coming from? A wearing out water pump?

 

Take the serp belt off, if the sound goes away, it's something that's being driven by the belt. Check the water pump for play, any play, looseness or roughness and it's the WP.

 

It was definitely the water pump. Here's the old next to the new one. I'll get a recording of the sound (or lack thereof) as soon as I finish getting the coolant flushed and refilled. For what its worth, the missing impeller blade from the old pump was stuck in the thermostat.

 

And here's the final product. All fixed. Excuse the awesomely loud exhaust - I was still running a straight pipe on the driver's side.

 

Thanks Fixxxer. Very helpful for us novice mechanics who spend our days behind a desk.

 

Wow! What an awesome thread. My water pump went out today and at first I expected the worst. However noticing that there was no smoke, no loss in oil pressure, I figured it was the pump. I drove slowly straight to the shop and they confirmed it was in fact the pump. Thanks for posting this as others can see and have a great idea of what could be going on with your car and not the IMS or something. Cheers!

 

I spend my days behind a desk too!

Glad it helped!