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: 73,915 (33,456–160,000)
Engine affected: 3.7L 5 Cylinder
3 model years affected: 2006, 2007, 2008
40 people reported this problem
26 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 !!!
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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!!!
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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.
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2007 Hummer H360,000
Rough idle, cylinder head is bad, just out of warranty. Shame on GM.
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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!!
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 H357,000
bad cylinder head, soft valve seats
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
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.
The idle is getting rough and it almost stalls out when coming to a stop. I am shifting it manually and throwing it up into neutral at lights. No engine light yet but the code may be in there, haven't taken it to a dealer yet but when I do for the heater fan recall, I will have them check for error codes then. HAS ANYBODY HAD ANY LUCK GETTING GM TO FIX THIS WHEN YOU ARE TOTALLY OFF WARRANTY?
2007 Hummer H3104,000
blown valve seats causing misfiring. engine light on. cylinder #3 at 90% PSI
2007 Hummer H397,000
Cylinder #4 no longer holding pressure, they want $4k to fix it.
2006 Hummer H3160,000
Three of the cylinders are misfiring and the dealership said that the cylinder heads needs to be replaced and that they also might need to replace the timing chain. We're talking $5,000 PLUS!! I'm getting a second opinion. Something is wrong.
2006 Hummer H3115,300
check engine light came on, took to Chevy dealership they informed me that I need a new cylinder head
2006 Hummer H397,000
Just found out its misfiring. Only notice it when the truck is in reverse. Firestne says it'll cost $3000 to fix. Guess i need to put in some OT!
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.
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.
Ive been giving the same run a round by GM since Dec. 2013 until Easter 2014 with no help at all from GM. Was even told by a GM so called cusomer assistance rep that MRS. Barra's comment about standing behind there product, meant " standing behind the products coming out now" Really?? Also was told by a GM tech that if I dropped a valve because of this that id lose ALL CONTROL OF THE VEHICLE. when I told GM that said they couldnt help with replacing the valve seats because there wasnt a recall. I guess someone has to die first before THEY STAND BEHIND THERE PRODUCT. Was also told this issue is a result of GM using a 3rd party company and these valve seats were made for LAWN MOWERS , yes you read that correctly MADE FOR LAWN MOWERS..!!!! SHAME ON GM! ISSUE A RECALL!! DO WHATS RITE!
2007 Hummer H395,202
Problem started @ 80,902 but not fully diagnosed until today. Misfire cylinder #5 caused by valve train issue. Dealer recommends replacing head, valves, etc.
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