Hi all. I have a 93 Sub K1500. Anytime I press the gas pedal, it makes a knocking sound. I know there are tons of different sounds that an engine can make, but is there one that is more likely to happen only when accelerating? I already replaced the valve lifters and adjusted the valves, and at this point it really doesn't sound like valve rattle. Most of what I've read says to listen with a stethascope(sp?), but that's hard when the sound only occurs with the vehicle moving. O-ya, I guess I should mention that it only occurs when accelerating, under load (so not just reving the engine while in park). I also replaced the EGR (or ERG?) valve, but not the solenoid or MAP sensor. I've adjusted the timing a lot also, with a light.

 

Ar you sure it is not coming from the transmission near the back of the engine? Does it do it if you power brake it?

 

Thanks for the suggestion. I'll try that when I get it running well enough for a test drive. Will probably be a few weeks as I'm about to start vacation (way too hot here, need to get out of town for a while).