gmt400 1999 GMC Yukon SLT Engine Problem

[Blackandgold51]

I have a 1999 GMC Yukon SLT with a 5.7 liter V8, and the problem I have is when the engine is running there's a little "knock, knock, knock, knocn" noise like an old beat up 70's American Car. The Engine does run fine nonetheless, but that "knocking" sound is the only problem.

 

[dz2a8r]

a tick tick tick noise is sometimes ok but a knock knock knock usually means something bad, use an automotive stethoscope, or a broom handle if you dont have one and place one end against the oil pan and the other end to your ear, thisll tell you if its a low end knock or not, if its pretty loud could be a rod bearing, if its not loud, put one end of the listening tool against each of the heads and see if the noise is louder there. Judging by the way you say the engine runs fine other than the knock im going to go with rod bearing