Engine Misfire Due to Worn Valve Seat on Hummer H3

The engine may develop a misfire due to worn valve seats. This fault will cause the Check Engine Light to illuminate. Replacement of the cylinder head may be required to correct this concern.

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Average mileage: 83,394 (33,456–199,999)
Engine affected: 3.7L 5 Cylinder
3 model years affected: 2006, 2007, 2008
58 people reported this problem
39 people shared problem details
2008 Hummer H3- 3.7L 5 Cylinder41,000
Dealer had to replace heads...still under warranty... if it was not it would be big $$$...Gm should do a recall !!!
Same rough idle & check engine light on. Took to dealership under warranty, they said misfire on #5 cylinder & need to replace head. They said it is a common problem with H3. One year later, same problem. Have to take to dealership again. GM NEEDS TO DO A RECALL TO PERMANENTLY FIX IT!!! ITS RIDICULOUS IF THEY ALREADY KNOW ITS A PROBLEM!! I am thinking of getting rid of the vehicle after its fixed because I only have one more year of warranty left & its ashame because the vehicle is very good with no other problems ever with it.
2008 Hummer H3- 3.7L 5 Cylinder82,500
Engine light came on; 2 months after warranty expired, so brought it to dealer and found cylinder 5 pressure was low and need a new head....$2657 later it's as good as new. GM WHERE IS THE RECALL!!!
2007 Hummer H360,000
Rough idle, cylinder head is bad, just out of warranty. Shame on GM.
2008 Hummer H3- 3.7L 5 Cylinder43,550
Check engine light keeps coming on. Have had it on machine twice both times show recent engine misfire. the second time it pin pointed #5 cylinder.Mechanic switched #4 coil and plug with #5 problem still in #5 cylinder. Problem is still in #5
2006 Hummer H394,500
2008 Hummer H3- 3.7L 5 Cylinder40,666
I first noticed an intermittent rough idle when starting the engine while cold. The rpms would hesitate then drop suddenly to below 500 before jumping up to around 1100 and normalizing without any other issues while running. As it started to happen more frequently, I brought it to the dealer and was told that there was no check engine light and they weren't able to recreate the problem. I brought it in twice more and had the throttle body and injectors cleaned before catching a rough start on cell phone video and brought it to the dealer for the fourth time. They advised me that the check engine light should have been lit, but never came on and there was a misfire trouble code. The service report said that there was an "erratic misfire on cylinders 1-4 and a consistent misfire in cylinder 5". They compression tested the #5 cylinder and found the pressure was low due to "leaking exhaust gases". The cylinder head was replaced in accordance with service bulletins and thankfully under warranty.
2006 Hummer H382,000
Cylinder 2 misfire. Bought used with no warranty from dealer in 2010. Dreading repair costs to fix it. The idle is so rough now and I put so much money in it thinking I was getting a quality car. Now pissed at GM and will never purchase a car from them again the do not stand by the customers or product and give the recall as necessary.
2006 Hummer H333,456
Engine light illuminated several times over a 2 week period. Initailly, dealer suggested that I check the fuel cap and\or purchase fuel from a "different" station. However, neither of the suggestions solved the problem. Major work (replace head) was required on vehicle. Dealer estimates it will take at least a week to fix it. On a good note: it's under warranty!!
2006 Hummer H357,000
bad cylinder head, soft valve seats
rough idle, in shop now, tech says code shows seepage in cylinder, doing a leak test now. Final report: bad head. Just out of warranty. Cost: $2335 to replace.
2006 Hummer H384,000
Same as others , #2 and #5 valve misfire need new head. Why is there not a recall on this?
2006 Hummer H367,000
Very low milage on th car. Check engine light came on while on a road trip. Took th car to a mechanic twice. 2 heads have misfired. Can't smog and repair is getting more costly.
I have had the cylinders replace 3 times! once at 74,240, once at 90,0010, and again at 127, 277! this is ridiculous! and although I love this car GM knows they have made a faulty product and refuse to stand behind it and fix it! showamom13@aol.com
Rough Idle Check Engine Light constantly OnStar Diagnostic Mechanics have checked Found out it is a common problem and GM knew about it and decided to screw the Americans like all of corporate America
Its was diagnosed by professionals at the college by the mechanics instructor, have not got it fixed yet, waiting on prices on the new head.
2006 Hummer H3129,000
Major clicking when accelerating, has gotten worse since yesterday, taking it for repairs tomorrow. Not under warranty, so that'll be fun...
2006 Hummer H386,542
Cylinder misfire code, low compression across the board. Given the known problem why no recall on poor quality parts. Where do I sign up for a class action law suit against GM
2007 Hummer H384,000
2008 Hummer H384,000
leaking cylinders. top of engine needs to be replaced
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