F engine help

[eddybear]

After my mechanic installed a new valve cover gasket and MAF headers he took my 1972 FJ55 on a 15 minute run down the interstate w/ no problem. I drove it a quarter of a mile when it began to hesitate and cough and then it blew exhaust back in thru the interior vents and lost power. I looked underneath and saw oil pooling on the ground due to:

1) the dipstick having been blown out
2) the new valve cover gasket blown partially out thru the side of the cover

Several folks have told me that it may be:

1) fuel pump leaking fuel into the crankcase
2) bad rings and a shot engine
3) a bad oil pump

The mechanic checked the PCV valve for blockage and it checked out OK. The engine was fine and has a new carb and nearly every other mechanical part replaced over the past year. Any ideas on what could have caused the pressure that ruptured the gasket? Thanks in advance!

Eddy

[Ground Up]

Sounds like the PCV valve. I had a bad one on the 45 when I got it made a horrible hissing noise. I think it was IDave that had the distributor launch a gusher of oil from the pressure built up.

Remember I am no expert! Just a thought. Black smoke may have been from the oil burning on the exhaust manifold.

[cruiserbrett]

Well, you can rule #3 out. what happened to your engine has to do with crankcase over pressurization.

You can try to start it back up after checking oil level, but leave the oil fill cap off, and once running check blow by attempting to cover oil fill hole with your hand and a rag. In a vehcile with a functioning PCV system and *normal* blowby, you should easily be able to cover over the oil fill cap without the pressure trying to escape despite your hand an rag pressing down on the hole.

If it tries to blow out anyhow, you should check your mechainics PCV evaluation.

[65SWB45]

eddybear, if we stop to eliminate the valve cover gasket from the equation [it is the victim, not the culprit] then we only have the header installation as the variable that changed. In the process of changing the header, a few things could have happened.

1. Something could have gotten into the carb.
2. Intake manifold seal to head could have been compromised.
3. Exhaust seal could be compromised.

None of these stands out as likely cause of excessive crankcase pressure. So I am going to go back to the valve cover gasket.

I agree with the others that your situation is the result of crankcase vapors. It is possible to have crankcase pressure build up faster than your PCV system can handle it, especially if you have worn rings and/or valve guides.
So, I am going to go with the hunch that you have fairly low compression readings on your cylinders, and that the excessive crankcase vapors were able to release themselves from the engine via the old valve cover gasket. Once you got a valve cover to seal properly, you in effect created a new problem. The blowby could have actually reached the point where it was backing up thru the rings into the combustion chambers, lessening the demand from the intake manifold, thereby causing the loss in power.

It's an interesting theory anyways. You could confirm it with a dry and wet compression test.

If I am right, then you can be VERY GLAD that it did not take out the rear main seal. I saw that happen to a customer in your situation.

[65SWB45]

bump. Just had to. Main board not registering any postings in the last two hours on this thread?