lower knock in my 5.3 vortec

[flanker1970]

I have a 2001 tahoe with a 5.3 vortec. When I first start it up, it has a noticeable knock coming from the crankcase. It sounds like a few rods are knocking. I have a hard time believing that it is a bad bearing or wear and tear. I've owned it since new and have anal with its maintenence and operation. It has 94,000 miles on it. Any ideas? thanks

[pat mccarthy]

did it ever have a leaky intake if so the antifreeze gets in the oil and in time will take out the rod bearings i have seen some that were fix and down the road the rods go out

[gwaidman]

Pretty common on the 5.3 and 6.0 engines to have a little piston slap on start up. IF you search it on the net you will see. My 01 Suburban does it to and has for quite some time. 150k on her now and no worse. Just ticks me off to have any noises coming from a 'new' vehicle.