2009 denali 6.2 no compression in # 7 #5 190 lbs same in 3 . I removed the valve cover and was thinking the lifter wouldnt be working but all rockers were moving. It looked a little dry , not sure no oil during the compression test. dont know if I should just remove the head and inspect or attempt to a lifter repair for stuck lifter? not sure what to do . Hav 190000 miles should I pull both heads and replace all lifters etc?
afm 2009 denali 6.2 no compression cylinder 7
- Thread starter hawaii
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swathdiver
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Your L9H does not have AFM. But you may have a dropped valve seat or bad lifter sill or even a bent pushrod or broken valve spring. Did the car get hot recently, run low on coolant or something? A dropped valve seat is a common occurrence when 823 heads get overheated.
It is SOP to replace the lifter trays when replacing any lifters. Make sure you use GM OE trays.
It is SOP to replace the lifter trays when replacing any lifters. Make sure you use GM OE trays.
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petethepug
Michael
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I agree look closely at the valve springs for one to be broken and a valve no closing all the way.
if you have an air compresor, you can usually use your compression tester, pull the valve core out of it and use it to put air into the cyl and hear where it's leaking from. just turn the motor by hand to top dead center for that cyl so both are closed.
if you have an air compresor, you can usually use your compression tester, pull the valve core out of it and use it to put air into the cyl and hear where it's leaking from. just turn the motor by hand to top dead center for that cyl so both are closed.
In addition to the other great recs here, I bought a cheap little borescope from scamazon that works great. It’s worth taking a look around in there to avoid having to remove the head.
donjetman
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Harbor freight has cheap boroscopes too.
not hot , started with loud ticking followed up with no compression in cyl 7 . are you recommending pulling the head or both heads with the mileage?
an l9h I did not know that no afm ?
wjburken
Supporting Member
Just a point of information......
#7 is the cylinder that tends to get valves fouled up by the old valve cover design that let a large amount of oil into the intake through the PCV port which then pools at the back and drains into the #7 intake valve. This tends to cause crap to build up which can cause issues. The 2009 would have this design if I am not mistaken.
I am not sharing this to discount what others have shared; only to give some more things to look for when diagnosing the issue.
#7 is the cylinder that tends to get valves fouled up by the old valve cover design that let a large amount of oil into the intake through the PCV port which then pools at the back and drains into the #7 intake valve. This tends to cause crap to build up which can cause issues. The 2009 would have this design if I am not mistaken.
I am not sharing this to discount what others have shared; only to give some more things to look for when diagnosing the issue.
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