What's Normal Compression for a 22R

[drj95018]

I have recently acquired an 85 4X with a 22R motor. It's overheating and using water, although there is no oil in the water or vice versa. I hear head problems are common in this motor and (thankfully) got the truck cheap enough that I have no problem with pulling the head and having it rebuilt, but was wondering if it was worth it on an engine of unknown lower end health. I did a compression check (cold engine) and got 170-180 across the board. So the question is, are these compression readings Good or OK or Poor?

Thanks
DrJ

[Brian R.]

1st - Check your oil pressure. If your lower end has good clearances, then your oil pressure will be normal. Minimum of 4.3 psi at idle and 36-71 psi at 3000 rpm.

Compression should be around 170 psi, minimum of 130 psi. They should all be fairly even at any reading above 130 psi. 170-180 looks good for compression. Might actually be a little high - indicating excessive combustion chamber deposits. Run some SeaFoam or GM Top Engine Cleaner through the engine via the intake.

[KimMG]

Pressure test the cooling system to check for small leaks. Also pressure test the radiator cap.

[Brian R.]

Originally Posted by KimMG

Pressure test the cooling system to check for small leaks. Also pressure test the radiator cap.

This is definitely the way to go before you replace the head gasket. Your leak could be anywhere. Head gasket is the last thing to replace to fix a coolant leak.

[corbinwaterski]

I have read alot about the coolant escaping out the exhaust valve on the #4 cylinder. Apparently the coolant, if improperly mixed, will eat away at the aluminum block??? It's worth checking out. Good luck.

[Brian R.]

Originally Posted by corbinwaterski

I have read alot about the coolant escaping out the exhaust valve on the #4 cylinder. Apparently the coolant, if improperly mixed, will eat away at the aluminum block??? It's worth checking out. Good luck.

That is truly bizarre. It's supposed to protect the head, not react with it. Maybe it just leaks there through a crack in the seat or something else from an unrelated cause.

[corbinwaterski]

Yeah, I thought that was bizarre, and it may just be "talk"! It is hard to say. I have come across it several times, both in this forum and "others"!

http://www.automotiveforums.com/vbul...t=coolant+leak

It looks like the #3 valve, not the #4. Ferrrous block w/aluminum head.

[Brian R.]

OK, I see. He reports that this problem occurs when you run water or very dilute antifreeze in the engine. That I can believe. The antifreeze doesn't kill it, it just doesn't protect it because it is too dilute or non-existant.