- February 25, 2017 at 7:04 pm #15095
I have a Alero with a 3.4 v6 and recently was driving down the road and stopped to get gas and when i got back in the car and turned it back on it started knocking. It also lost power. The noise sounds like its coming from heads and speeds up with engine when i hit the gas. I have already replaced oil pump, oil screen, knock sensor, flushed engine changed oil, it was still making noise. So a couple days ago we tore apart engine and found that 2 valve springs were broke(one on each side) but no bent pushrods, and we took out the hydraulic lifters and they all looked good.
We figured it was something with the springs so we replaced all 12 and went and got a new gasket set then put it back together. Started it up and its still making noise. And now its idling high and slight whistle.
How do you check lifters? And what else should I check? And we are thinking about buying two new heads will that help?
Reply: Assuming everything was installed correctly, correct 3.4L pushrod location order and you still have a top end noise, i have not had springs break on this engine. Have had a lot of rocker arm bolts pull out of the cylinder head. Re-tapping and installing a heli-coil fixes that. Lifters should not be able to be compressed by hand using a pushrod. That is about the only way to check them. A whistling noise is usually a vacuum leak.