Engine Rattle

plinkie · May 24, 2007

2000 Sierra,5.3 2 wheel Drive,auto. 108,000 km. When accelerating, there is engine noise that sounds similar to a noisy valve lifter. It is mostly at around 2000rpm that it makes the noise. No noise if you idle engine, or even rev it up at a stand still , but once you put it into drive, and accelerate, you can hear an irretateing knocking noise from engine. As long as I am not accelerating, the engine is quiet. Even at 120 km, no noise. But slow down and accelerate again, and engine noise comes back until you quit accelerating. It isn't real loud, but as I said, sounds like a valve lifter noise. Same when engine is hot or cold. IF this was a lifter, wouldn't I be able to hear it at all times? Driving me nuts! Thanks for any ideas.

jhm · May 25, 2007

Is your truck 4wd? Does it have floor mounted selector?

jhm · May 25, 2007

sorry, didnt notice you said it was 2wd.

1999 Tahoe 4x4 · May 27, 2007

2000 Sierra,5.3 2 wheel Drive,auto. 108,000 km. When accelerating, there is engine noise that sounds similar to a noisy valve lifter. It is mostly at around 2000rpm that it makes the noise. No noise if you idle engine, or even rev it up at a stand still , but once you put it into drive, and accelerate, you can hear an irretateing knocking noise from engine. As long as I am not accelerating, the engine is quiet. Even at 120 km, no noise. But slow down and accelerate again, and engine noise comes back until you quit accelerating. It isn't real loud, but as I said, sounds like a valve lifter noise. Same when engine is hot or cold. IF this was a lifter, wouldn't I be able to hear it at all times? Driving me nuts! Thanks for any ideas.

I had the exact same thing. Sounded exaclty like a one valve lifter is faulty. Frequency, metall on metall sound everything...

I Just fixed it. It was the exhaust doughnut. See my post "5.7 Ticking on Accelleration"

plinkie · May 27, 2007

Thank you. I will check your post. I had one other person suggest to me as well that it could be an exhaust problem.

ryank1 · May 30, 2007

Check your pcv valve and the hose, I have seen more than once a bad pcv valve causing a tapping noise or simply the pcv hose is laying against the throttle cable and the noise transmits