BGSilverado310

Hello! New to the forum here. I'm reaching out to you knowledgeable people as a desperate measure. Sent in my last payment and warranty has expired. I do not work on vehicles other than changing oil and brakes.


Check Engine came on at 56,000 miles. Along with the service stability track and service Tire Monitor System. Care would shake at idle and really shake when I let the brake go without stepping on gas. But once I get going it was fine.
I checked it and showed a P0303 code. Cylinder 3 misfire.
Took it to the mechanic and we checked the coil, plugs and injectorws. All are fine.
He hooked up a device that screws onto the spark plug with a gage and it showed the compression at approximately 50 pressure/compression which is very low as others over 150.
Decided it needed a valve and head job. Got it done. $1200. Says that the machine shop did a compression check and everything is fine. Picked up the truck and bam same issues (shaking and same codes). I take it back and he said that he's going to take it apart and send back to the shop to double check and he will diagnose it again.
Call him yesterday and he said that the compression is between 150 and 160 however, when you begin to drive it the compression shoots back down to 60.
He says that we need to do the bottom part of the engine and mentioned piston ring.


My question is shouldn't this be a recall or something? I shouldn't have to overhaul an engine at 56,000 miles. I take very good care of vehicle. Thank you for any input you may have.

cleveland63b

In my opinion it sounds like your mechanic is taking the shotgun approach and not fully diagnosing anything. If compression was low he should have done a cylinder leakage test to pinpoint where it was being lost instead of just rebuilding the heads. I would do a cylinder leakage test, also if you can physically feel the misfire at idle then if compression was the issue it would normally show itself on a normal cranking compression test. That low of mileage I would suspect an ignition system or injector issue but I'm not there to see how or what was tested.

BGSilverado310

Thank you for your response Cleveland. I took it to another mechanic and he said that he just fixed two other Silverado's with the same problem and says that it's the Camshaft and Lifters. I've read other complaint about this problem (AMF) dating back to 2008. Problems occur right after the warranty expires (Class Action ?). Having to redo an engine at 58,000 is unacceptable! I have a few more questions, if you guys can shed some light on this for me.


1) Has anyone had this problem. Did you fix it and did it happen again?
2) Do the GMC 5.3 engine have the same problem?


I'll keep it if I can fix it and drive it for another 5 years. If not, I'm going to trade it in. For what, I don't know! Than you in advance for your response(s) guys.