I am hearing a rattling sound from behind the engine when driving around 800-1200 rpm, it only rattles for a couple seconds. Its very constant every time i am stopped and start accelerating I hear it. I never hear it at higher RPMs. Does any one know what that sound is? I could have swarn I heared the same sound on the last 928 before something eventually snapped and I could not go into any gears. Anyways the car is a 1989 928. I am in Middletown, NY (just got here on Friday) if anyone has time I could drive by their house. I am going to use a lift tommorow the change my oil I think it would be a good time to see what could be loose or broken. Any pointers or places to look?

 

check the motor mounts see if they are collapsed then the manifolds will be hitting the side braces of the crossmember.
See if the air injection tube to the cats is loose
See if anything is hitting the firewall under the air cleaner
Check the tightness of the front pinch bolt on the flex plate
Check the heat shields make sure they are not hitting anything
Check the power steering lines where they attach to the fender well

Thats a start

 

They all do that.

No seriously - it seems that many S4 transaxles make that noise when you start moving while lugging too low in the rev band. My '89 does it, and I have come across at least 2 or 3 threads asking about this same phenomenon.

Solution - start moving from a lower gear or with more engine speed.

 

One of the advantages of having a 928 is that basically everything You experience, has been experienced by someone else before You and been discussed in this beautiful forum.

See thi sthread: https://rennlist.com/forums/928-forum/337177-5-sp-transmission-questions-and-discussion.html


Ragnar

 

My '85 does it too. I thought the TO bearing or something was worn out.





The more I drive my 5-speed, the more I like my auto. Stab it n' steer!

 

5-speed or auto?

My guess is torque tube and/or torque converter bearings.

 

My guess is a loose heat shield.

 

On my car, there's a nut behind the big wheel that gets loose. More whining than rattling when it happens though. Very pronounced when it does. Doesn't seem to do it when others drive it.

To the OP--

Front torque tube bearing likes to move around in old age. You can pull the bellhousng inspection cover off from below and feel back with a coathanger, looking for a bearing maybe six inches back in the tube.

Since you have access to a lift on base, put the car up and run it while someone listens underneath. A stethoscope will find the bearing noise, and a gloved hand will quiet a ratting heat shield. Hope it's a heat shield!

 

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