Diagnosis needed, no compression, help pls

[1995Tahoe]

1995 Tahoe, 5.7L TBI
180k miles
"Rebuilt heads" from previous owner

Ran compression test, 8=120, 6=120, 4=110, cyl2 was at 0, needle didn't even flinch when cranking. New plug in 2 was covered with soot. Bad tick from passenger side of engine. Bad power, bad fuel consumption. Oil pressure goes down to almost 0 while driving, but will increase under high RPM. BUT no smoke. strange. what are the chances it's rings? Thanks all.

 

[DallasTahoe]

1995 Tahoe, 5.7L TBI
180k miles
"Rebuilt heads" from previous owner

Ran compression test, 8=120, 6=120, 4=110, cyl2 was at 0, needle didn't even flinch when cranking. New plug in 2 was covered with soot. Bad tick from passenger side of engine. Bad power, bad fuel consumption. Oil pressure goes down to almost 0 while driving, but will increase under high RPM. BUT no smoke. strange. what are the chances it's rings? Thanks all.

Sounds familiar, I'm thinkin blown head gasket between cyls 2 & 4 or atleast partially between the two cyls.


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[1995Tahoe]

Sounds familiar, I'm thinkin blown head gasket between cyls 2 & 4 or atleast partially between the two cyls.

The heads were just rebuilt from the previous owner tho. You still think it's the head gasket?

 

[DallasTahoe]

Unless you have a camera to fit in the spark plug hole to see, or maybe pull a valve cover to see if maybe you have a broken valve spring, the only way to really know is to pull the head


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[SunlitComet]

a blown gasket will not cause a zero oil pressure issue. inspect your valve clearance for that dead cylinder and strongly consider you may need to tear off the top end for more clues.

 

[SunlitComet]

also if the rings alone caused no compression you would see smoke. and if ring caused zero compression, you can kiss that piston and cylinder hole good bye. pressure issue is either bad bearings, clogged or broken pump or blown lifter but the last is very unlikely.

 

[1995Tahoe]

the only way to really know is to pull the head

What would I be looking for?

inspect your valve clearance for that dead cylinder and strongly consider you may need to tear off the top end for more clues.

Inspect valve clearance like if it's hitting the piston?

Like above, what would I be looking for if I were to pull the head?


Thanks.

 

[1995Tahoe]

Aaand it just backfired on me on the way to work. I was making a somewhat sharp turn, nothing crazy though.

 

[ccapehartusarmyINF.(ret)]

backfireing indicates lean mixture wich points to valve timing

 

[DallasTahoe]

backfireing indicates lean mixture wich points to valve timing

Backfiring doesn't indicate a lean mixture, it indicates timing


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