Zmazmzm

My buddy has a 94 4x4 pickup. It was running poorly last year and a mechanic told him he needed a new motor. He came over we did a compression test and had 170-180 psi on a warm motor everywhere but passengers side firewall piston. This one is stuck so no test. I found 2 broken vacuum lines and the rest were brittle. We replaced all the vacuum line. It ran a little better.

Still having hesitation and low power, we ran a can of sea foam through the brake booster line doing it the right way with a soak at the end. That really fixed it up was getting egr cel before after sea foam it ran great until this weekend.

This weekend it started getting hot coolant disappearing ect. I told him stop driving it and came over tonight. Radiator cap is clean but oil has water in it, I've seen worse. Starting it whitish grey smoke sounds okay makes power. Cold compression is 150-160 except that passengers side firewall plug that is stuck.

It's a made in Japan 3.0 v6 with nearly 200k miles.

Oil and smoke lead to head gasket but I am looking for lower numbers on the compression test. The gauge holds 150 psi too no leak down after cranking. No wet plugs exhaust smells like oil not sweet antifreeze.

What do you all think?

wyoming9

iTrader: (1)

I think you need to get that stuck plug out.

Pressure test the cooling system that will tell you if the cooling system is leaking if it does not hold pressure .

Do this cold nasty burns from hot coolant.

Zmazmzm

When I left last night the froze plug was soaking in pb blaster. I got on it with a 1/2" drive breaker bar and it didn't budge. It's as likely to break off as it is to come out. Guy who did the plug didn't use anti seize and put the in way too tight. When I did the compression test last year I put anti seize on the five I could get out. My buddy joked with me last night that when they got to that plug they were out of anti seize so they used seize. I told him it worked.

I'll pressure Test the cooling system.

Would you agree that 150-160 psi across five plugs is probably not a bad head gasket? Where else could coolant get into the oil?

RJR

Murphy would say the cylinder that's bad is the one you can't test because of the stuck plug.

Usually the spark plug threads don't totally gall up and seize until someone tries to force it instead of working it out gently and patiently. If you've never had that plug out, there's a good possibility the previous owner/mechanic tried to get it out, backed it out enough to where the threads started galling in the aluminum head, forced it until it was good and jammed, and left it stuck there.

If you haven't already, I would suggest trying to turn it tighter. If you can get even a hint of motion, you may be able to work it back and forth and eventually free it. It can take a long time - patience is key here.

bswarm

Does it crank over evenly with all the plugs in? Before we worked on any tuneup related issues, we listen to the way the starter cranks the engine. If it cranks at an even speed it's usually ok compression. If it cranks over normal/fast/normal/etc then it's at least one cylinder low on compression. We'd follow up with a compression test.
Another thing, I've pulled heads off where the spark plug wouldn't come out and found melted plug/piston damage from severe preignition. I've even seen pistons with holes burned through.
I don't believe in using anti-seize on spark plugs, if they're put in at the right torque there's no problems getting them back out.

Zmazmzm

So my buddy traded the truck. It's interesting it stopped smoking except on start up. I think all the smoke the time I did the compression test was from sitting and oil pooling through the valve seats. It ran fine until it lost all coolant then ran hot. As long as he kept water in the radiator no issues. I'll be interested to see what the new owner finds. I told him to pressurize the cooling system and look for leaks.