Cylinder head/gasket dilemma

[redfishsc]

Ok guys, L31 MaxExpress was definitely right.

Started pulling compression numbers.

Cyl #1 was 170psi
Cyl #3 was 158
Cyl #5 was 135. So i checked the adapter for fit and retested a few times. Then I got WATER out of the gauge purge valve. Quite a bit. (only water in the rad right now)


So I stopped there since the gauge had water in it and I put the plugs back in.

Found a local source for reman heads for about $200, which I probably will buy. I'll put in the MFI injectors
while I'm at it.

 

[Schurkey]

Leakdown test might tell you if the low compression is from valves or rings or bad head gasket/cracked casting.

If it's rings, you might as well pull the engine to freshen it. It's very possible that a "rings, bearings, gaskets" short-block job, plus cylinder-head inspection and a valve job if needed, or outright head replacement would set that engine right for a very reasonable price.

 

[redfishsc]

Is there any way (other than teardown and visual inspection) to detect whether this could be a cracked block?

I know the heads and gaskets on these are far more prone to failure than the blocks but of course getting coolant in a piston gets one concerned.

Thankfully I've never found coolant in the oil and it takes several thousand miles before synthetic oil begins turning dark amber. Nor have I noticed blowby from the oil fill or dipstick.

 

[Schurkey]

Is there any way (other than teardown and visual inspection) to detect whether this could be a cracked block?

No. But if it passes a leakdown test, it's maybe worth taking a chance.

Pressurize the cylinder with compressed air, see if there's bubbles in the radiator or the cylinder(s) next-door. If there's ANY, the engine comes apart.

There should be NO leakage audible at the throttle body (intake valve) and NO leakage audible at the tailpipe (exhaust valve.) If there is, the engine comes apart for valve/guide/seat work. You will have leakage at the oil fill cap, some leakage past the rings is inevitable. If you use a real leak down tester, you'll have a gauge to know if the leakage past the rings is acceptable or not.

 

[redfishsc]

Sorry I never updated this post.

#5 cylinder head was definitely cracked. Not a huge crack like my other 99 had, but a crack nonetheless.

I swapped the cylinder heads with stock iron remans from a local machine shop. New MPFI injectors while I was at it, the old spider injectors looked wretched.

Truck has been running like a champ for the past year. Had to replace the starter (was original starter) and alternator (don't buy Autozone crap) over the past year but other than that, she's a winner.

 

[XJPhoenix]

Thanks for coming back and updating us! It's nice to know that things turned out well for you.