Car Problem Reports

GMC Envoy Worn Valve Seats May Cause Engine Misfire

GMC Envoy Problem
26 Reports
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Model Years Affected: 2002, 2003, 2004, 2005, 2006

Engine Affected: 4.2L 6 Cylinder

Average Mileage: 87,944 mi (57,000 mi - 141,000 mi)


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.

  • Visitor, , 4.2L 6 Cylinder, 135,000 mi

    engine idles to rough told it was a cylinder misfire what does it involve is it expensive

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  • blue74nova, , 4.2L 6 Cylinder, 80,000 mi

    Cylinder 5 misfire , Pepboys said it needs a valve job , for $3400 and now GMC dealer says the head is leaking and it needs a new head, possibly a cracked head?, I read that this is a common problem and GM has changed this head five times so far, so they are prob trying charge me for a new version head and a vale job , $3500 to $4000, this car is way too new for this kind of problem, I don't tow anything with the Envoy or drive it hard, my wife actually drives the kids to school in it. There should be a recall on this problem, instead of keeping it quiet and letting the customer pay for this, I'm not sure what to do, but I know I won't buy another GMC.

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  • Visitor, , 4.2L 6 Cylinder, 57,000 mi

    misfire cylinder one, check engine on, "turn engine off" warning sign. no pressure. car white cloudy smoke, irregular idle, loss of power. warranty expired.

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  • BassAngler37, , 4.2L 6 Cylinder, 77,000 mi

    My check engine light came on. I took my car to a local mechanic and had it checked out, the mechanic plugged his device in my car and it read misfire in cylinder #4. The mechanic looked further into the problem and found out that cylinder #4 read a low 70lbs of compression and cylinder #3 has 120lbs of compression. He explained to us that the low cylinder compression was the reason why our car shakes while idling and runs rough when accelerating. He advised us to buy a new car or get a new engine.

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  • Visitor, , 4.2L 6 Cylinder, 80,000 mi

    i have a 2005 envoy with 80K miles, #3 cylinder has 50 Lbs of compression, guess im pulling the cylinder head....

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  • Visitor, , 4.2L 6 Cylinder, 117,000 mi

    Engine misfire at cyl 6. New plugs, etc., cleaned injectors, replaced intake manifiold gasket. No change. Removed head and had a burned exhaust valve at cyl 6.

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  • Visitor, , 4.2L 6 Cylinder, 88,000 mi

    I have a check engine light. I took it in a found out that it is my valve. Cant fix it right now. Driving minimal.

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  • Visitor, , 63,000 mi

    engine missing. problem was # 6 cylinder not firing. turned out to be valve and valve seats on head. Had to replace cylinder head.

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  • Visitor, , 4.2L 6 Cylinder

    i have the check engine all the time even if fifed it , it comes back

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  • Visitor, , 4.2L 6 Cylinder, 65,000 mi

    Misfire cylinder 6, dealer (Chevrolet) charged me over $1000 on repairs before diagnosing problem, Now wanting $2612 to repair bad valve.

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