GURU Stumper *'06 Trailblazer

A flat lifter?

Hi, I removed all lifters and inspected. Some were siezed but I managed to bring them back to life. When I was done cleaning them, they all seated nice and the springs were moving freely. I also blew them out with air then cleaner and they were clean. Any other ideas? This has been killing me!

When you had the valve covers off did you look for any valves that had clearance?

#3 compression is pretty low, how many miles on this engine?

Compression is off, either from timing, valves, or head gasket. P0017, possible cam actuator solenoid (most people assume it's a cam or knock sensor). This has the variable valve timing does it not? If it does then I'd look into timing issues.

I believe you may have "valve knock", meaning it is a clearance issue with the valve covers. Also, Bob is correct. Your #3 compression is low (should be closer to 200). I'm thinking you've got multiple things going on here. Check the inside of your valve covers to see if there's any evidence of contact there...that will likely be your noise source. Secondly, check your timing and see if it is off. Something tells me it is by a few degrees. Good luck with that one. If nothing works, I like the set it on fire option.

ok, I couldn't get past the part that says the "choke" turns off- it doesn't have a choke- but staring through the fog of confusion in my crystal ball, why don't you tell us how many miles are on this engine? It's a lot, isn't it? Why even bother warming up the ball to think about a "knock" on a worn out engine?