Mechanics

HEAD GASKET JOB GONE WRONG

1996 Pontiac Grand Am • 2.4L 4 cylinder FWD Manual • 200,000 miles

This grand am 2.4 had a new head gasket put on and has not ran since. I was hired to get it figured out. After making sure there is ample spark and fuel getting to each cylinder it still is not running and is barely even poofing at all. So I decide to see if they put the timing chain on right and discovered it was off a few teeth. They didnt put it on right or it skipped. So now im thinking valves are bent and compression test confirms that 3 of 4 cylinders have 30-40 psi while other has 130. I mentioned this to owner and found out they bent what he called a rod and had to replace it. Now im thinking all the exhaust valves are probably bent at the least. I have put alot of time into this and not sure if it is worth taking head off and trying to repair all of thisjust get a new motor. After I set the timing chain right the car started right up and sounded pretty good considering. Then a clanking sound from the top of the motor started and the motor shuts off. I havent tried to run it since but im thinking these bent valves are screwed and one gave completely. I realize with the compression values I should not have even entertained running it but I was curious if it would start. Any words of wisdom here before I move forward are greatly appreciated. Thanks
Avatar
Miles hubbard
November 30, 2013.




If it has enough compression to run with bent valves, they shouldn't make any noise. A cylinder leakage test is a better indicator of the condition of the cylinders than a compression test. A compression test will only tell you if the compression is low. A cylinder leakage test will tell you why. If it's just the valves, that's a lot easier job than replacing the entire engine. I suspect there's something else wrong because the 2.4L is not listed as an interference engine. The valves shouldn't have been damaged by incorrect installation of the timing chain.

Caradiodoc
Nov 30, 2013.
The noise may be coming from the timing chain area as well. I did not replace the tensioner and maybe its not functioning properly. Also, every forum I read says that this 2.4 on a 96 grand am is in fact an interference engine. Do we know for sure that it is or isnt. Thanks again

Tiny
Miles hubbard
Dec 1, 2013.
There's way too many engines to remember, so I refer to Rock Auto. They state when an engine is an interference design when you look at the listing for a timing chain or belt, or other related parts.

There was no reference there. If you found that this engine is indeed an interference engine, I have no reason to doubt that or argue with it.

Also, there are some engines with timing belts that will have bent valves if the belt is off only three teeth. Most interference engines can tolerate a little more than that.
AD

Caradiodoc
Dec 1, 2013.

AD