Ive got a 95 1500 5.7 4x4 suburban LT Ive got a strange knocking that that i cant pinpoint and looking for some ideas. I AM A MECHANIC so im not a dum dum but this has me stumped. Ok in the morning when its first started my motor has a light knock (not like a spun rod bearing but a knocking none the less. its not noticeable inside but outside it is if you listen for it. The knock is only at idle andwhen cold. once its warmed up it goes away ALOT. Ive gotten under the truck with a screw driver to listen with to try and pinpoint the knock and i can not find it in the motor. I know its in the general area of the passanger side rear of the motor. for litening to the motor without the screwdriver. the only thing ive noticed beyond that is that the exhaust does not have much pressure coming out the tail pipe and i dont have any leaks. Could a clogge dcat cause the knocking ? any other ideas?