I picked up a 07 suburban that runs but low on power, the guy I bought it from said him mechanic told him it jumped time which I found hard to believe since it’s running and I was able to drive it an hour home. It did have a detonation knock when climbing hills and is throwing a p0325 knock sensor and had a cam or crank sensor can’t remember which one and not showing up after the battery was disconnected. I did a compression check which I thought would be on the low side but instead was higher than normal.
1 - 210psi 3-230psi 5-235psi 7-235psi
2 - 230psi 4-230psi 6-240psi 8-235
i was expecting numbers around 135 for a motor with 240000miles. It hasn’t been worked on judging by the gunk build up on the heads, I thought maybe the exhaust might be clogged so I disconnected it but no chance in the compression. Its not burning oil or coolant I used two different compression gauges and used the gauge on my avalanche and it’s working fine, anyone have an idea why I’m low on power and have high compression numbers? Could it have jumped time like his mechanic said even though my experience has been compression goes down not up.

 

Can you hear a rattling noise coming from the front of the engine? Does it idle well? Does it accelerate well? Does run hot? At that mileage it probably does need a timing chain and sprockets.

 

it idles ok but not great, doesn’t run hot at all oil pressure stays around 40, the acceleration is very slow, no rattling that I can here. On the drive home wife didn’t see any smoke from exhaust.

 

Tore into it more looks like the timing was off, there’s slack in the chain one of the plastic guides was broken and 2 teeth on the cam gear are broken off. I can’t believe it was still running and the compression was higher that normal.