I am wondering if anyone knows what can mimic the sound of a blown rod? I recently thought I blew a rod - see my other post.

Yesterday I had the engine running for about 10 min. to move the car (keeping rpm's < 2500). There was no smoke, it developed good oil pressure, but it sounded like a diesel. I'm keeping the engine off to avoid any further damage. Are there any other parts that would make this sound, and can I figure it out without tearing the engine apart?

Thanks for any advice. I don't have nearly the mechanical sophistication of you guys on this board.

 

Its next to impossible to troubleshoot this remotely, but a few things might help a little. I suggest pulling the spark plugs to see if one or more look different than the others. This might show a bad cylinder, and lead to a valve problem. Also, you could do a compression test on each cylinder to check for obvious issues. This isnt too hard and a cheap gauge is available at Autozone/Sears. If you can stand running the engine after these tests, try and isolate the noise, could it be a tensioner that broke (by chance?) or some other chain issue? Also, I would pull the valve covers and check for a broken head stud. I know, this isnt characteristic the sound you are describing, but they can make quite a bit of noise if one breaks.

This doesnt really solve your problem, but should give you some insight on whats wrong.

 

Thanks, Chris. Good starting points.

 

seamd,
Try disconnecting the spark plug wire on the suspected cylinder while it's idling. The noise should reduce on the cylinder with the bad rod bearing due to removal of combustion load.

Hope this helps,
Sherwood Lee
<a href="http://members.rennlist.org/911pcars" target="_blank">http://members.rennlist.org/911pcars</a>