I'm trying to help a friend with a bone stock 03 with an auto. The motor has a knock that sounds like a bad bearing. It has a rough idle and no power. It starts fairly easy,has no codes and does not smoke. I can see nothing wrong with the valve train. Is there anything else that we could check before pulling the head and/or motor?

Something just doesn't add up to me. I can understand if it has a bad bearing why it has the knock but why the rough idle and lack of power?

Forgot to mention that we will do a compression test before we go any further. Any other ideas?

 

Got a stethoscope? May be a good time to buy one. They can help a lot.

 

I did try the stethoscope the other day. Nothing conclusive but it sounded to me like it was coming from one of the back two cylinders. Bore scope was too large to go down in the hole for the injector nozzle.

 

bad injectors will cause a knock. rev the motro up does the knock increase if so then it a bearing if not and seems to stay the same or go away then its injector knock. only other thing it could be that would cause ruff idle is a valve seat, but hat brings smoke and lots of it. had it happen twice