no compression in cylinder 5? What to look for? [Archive] - Forum


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05-18-2011, 12:21 PM
I found a 2003 grand am gt for sale. the body, and interior are in perfect shape. The guy told me that cylinder number 5 had no compression. He didn't say anything about the other cylinders. I am going to go look at the car this evening. I was wondering if there were any simple ways I could diagnose why it had no compression in cylinder 5? If anyone has any tips or advice for me that would be great. Thanks

05-18-2011, 02:17 PM
Well the valve cover needs pulled to see if the rocker bolt stripped out That a pretty common thing with these especially if its had a LIM gasket change

05-18-2011, 04:26 PM
So that would make there be no compression in cylinder 5? Also cylinder 5 is the back right if your standing in front of the car right? The guy kept calling it back left cylinder.

05-18-2011, 07:07 PM
Yes, cylinder 5 is the back right if you're standing in front of the car.

As unchained mentioned, check the rockers to see if the bolts pulled out of the head. Or for broken pushrods. If you see neither of those two things and still don't have compression, it may need a motor.

05-18-2011, 09:51 PM
Out of my own experience, it may be a floated valve, may need a valve job. Happened to my 03 at 118K.

05-19-2011, 06:21 PM
I went and looked at the car tonight. It was raining outside, and I didn't get to check out the rockers, or valves. I got to talk to the guy a little better tonight though. I guess it did have a little bit of compression in cylinder 5. All the others were good compression the mechanic he took it to said. The car started up and ran decently well. You could tell it was missing. It has kind of a ticking noise. It didn't sound horrible though. The oil looked good no water in it. Would the ticking noise maybe be a sign that its a rocker, or valvetrain related problem? I'm going back tomorrow to look at it again.

05-19-2011, 09:09 PM
The ticking definitely says valvetrain related. You may have a good fixer-upper on your hands.

05-22-2011, 09:49 AM
Well I couldn't figure out how to post a wma video on here so I posted one on v6z24. Here is a link to it. Anyone have any ideas what to check for? A mechanic told me he doesn't think its rockers. He said more likely to be lifters? What do you think?

05-22-2011, 09:51 AM,id,40655.html

05-22-2011, 09:44 PM
It was a rocker stud that pulled out. Just like you had said. I got a helicoil and fixed that, but couldn't find the push rod anywhere. Here it had fell down in the lifter valley through one of the other spots in the head. I couldn't reach it or get it with a magnet......So I had to take off the intake manifolds, and get it. Then it started storming when I got everything off. I didn't have it in the garage because it was nice out. So my day started out good thinking it was just gonna be the rocker, then gradually got worse. Hopefully tomorrow I can have it all back together. Thanks for the help guys.

05-23-2011, 08:59 AM
Glad you found it hope it all works out well for ya !! Make sure to put RTV in the corners of the lower intake amnifold or you will have an oil leak

05-23-2011, 08:17 PM
You're in the clear if you found the stripped rocker post. Good job.

Consider loosening and re-tightening the rest of the rocker arms with a GOOD torque wrench (read new and not harbor freight, well looked after or recently calibrated). This could save the others from pulling on you as well.

05-24-2011, 11:31 AM
Yes I ended up checking them all, and about 5 o them had threads in the the bolts.....So I went ahead and added heli coils to all of the ones that were starting to mess up. I got it all put together and it runs great now.