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I think my cadillac has a rod knock in cylinder #2, when i was adjusting my timing, i heard the knock. I started taking off spark plug wires one by one, when #2 was taken off, the knock went quieter. But when i took the stethiscope to the rocker arm bolt on the other side, i heard the knock VERY clearly. The oil wasn't changed very often in my cadillac thanks to and old granny, and it only has 94,000 miles!!!! I am positive that the knock is my lifters because they may be dirty. The knock is not around AT ALL when cold. Other than that, the engine runs like a clock, nice and smooth. It may also be my #1 main, right? The main bearing thump was also present in HT4100's. It sounds like a mallot knock, my oil PSI is perfect. I changed the oil 6 times within the past year and the car has not been driven much at all, maybe twice on the road. I did another one just uesterday, but added tranny fluid before change, lifter tick is gone. I added lucas oil stabalizer, and my oil PSI went up. The knock has been present ever since i had the car. Under the oil cap, the rocker arms look pretty clean, a GOLDEN BROWN. My question is, which one of these is the knock? I have a flowmaster 40 series delta flow and the knock is simeltanious to the sound of the muffler, so it must be the lifter(s). Would the oil P.S.I drop with a rod knock?
 

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A rod knock is an indication of 'looseness' in the space between the rod bearings and the crankshaft. If this space is large enough, it MIGHT change the oil pressure but, most likely, ONLY SLIGHTLY.

Same thing goes for the #1 main, where the change in oil pressure would be more likely.

Hope that helps some...
 
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