Cyl 4 misfire, coolant in cyl, holds 65lbs compression, new intake gask, help

[Bryyrtw1981]

I can figure out what's wrong with it. It's a 99 denali that I just got. It's throwing the cyl 4 misfire code, has coolant in the cyl but holds 65 lbs of compression,yes that's low, leaks down when doing a rad pressure test. Just put new intake gaskets on it and its still doing it.
Could this b a stuck valve or cracked head?
No oil in coolant or coolant in oil. Please help

 

[SunlitComet]

Broken head gasket? And was the test done with a WOT? Also when you put the intake gaskets on did you clean out the manifold to head bolt holes and use new sealant on the bolts or got new ones with sealant on them already?

---------- Post added at 05:55 PM ---------- Previous post was at 05:52 PM ----------

Matter of fact almost positive it is a bolt or head gasket sealing issue as the coolant passages in the manifold are in front of 1 & 2 on the vortec. Possibility of course you got or installed the wrong gasket too.

 

[Bryyrtw1981]

Yes I cleaned all the bolt holes out, use the new felpro gasket that everyone says to use, new bolts and torqued then in a x pattern goin form inside to out. Could the head b cracked at the #2 intake runner

 

[SunlitComet]

Right at the intake runner is not likely. I think you will have to take the head off and have it and its gasket inspected.

 

[Bryyrtw1981]

Yea I'm pretty sure it's head gasket. Jut shot some air into the cyl and coolant came out the lower rad hose.

 

[TahoeMV]

My Tahoe 1998 - 5.7L 4WD - light "service Eng soon" sometimes light is off but most of the time ON - code: misfire cyl#6. Slightly only shakes at idle, but perfect when runs or higher RPM. Compression on #6 is 105PSI and 140-150 on other. Any idea how to fix it
without expensive jobs. Thanks for help

 

[SunlitComet]

Evaluate your spark flug to find out if you are burning fluids in the cylinder. And if so what fluid. IF coolant it is possible the engine is savable becuase a broken head gasket could be be letting it in from the coolant flow paths as they are under pressure when hot. If oil only and absolutely sure there are no signs of coolant leaks no matter if you see blue smoke out the exhaust or not there are two possibilities. Do a compression test again(with WOT of course) and jot done the reading, and a teaspon or two of oil into the spark hole and do it again right away if the compression has improves more then 5 psi your engine is due for a rebuild. If no improvement at all it is likely a cylinder head will solve the issue depending on the damage to it. Your reading are out of range of what the engine should be operating under. No more then 20% difference between the highest and lowest reading and no cylinder under 100PSI.

 

[Bryyrtw1981]

Ok so too the head off and along with the gasket being bad, the head was cracked at the #4 exhaust valve and up into the exhaust runner. So I got a set of 520 head for 100$. Are they ok to put on or do I need to stay with the 062's?

 

[retorq]

I was just gonan say if you leak down from the chamber to the coolant passage you have a cracked head...

520 heads are old school 283 engines, not Vortecs. Vortecs are 062s and 906. Either is fine.

 

[SunlitComet]

Ok so too the head off and along with the gasket being bad, the head was cracked at the #4 exhaust valve and up into the exhaust runner. So I got a set of 520 head for 100$. Are they ok to put on or do I need to stay with the 062's?

NO! These units here are brand new GM vortec heads. It would be ideal to use them instead over remaned ones which may actually cost more then the new ones in local stores. http://www.jegs.com/i/GM-Performance/809/12558060/10002/-1