Thread: 352 valve cover blowby

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My son just bought a 1967 F100 with a 352 Fe and it runs great. The only problem is the old owner had a hose stuck in the valve cover breather port and it smokes like crazy while running. The carb has been changed and many vac lines plugged. the passanger side valve cover has a PCV valve with a vac line to the carb plate the driver side has only the one opening...The motor does not smoke from the tailpipes at all....My ? can we cap the opening or do we need to vac it back to carb?.... or what needs to be done? ANY HELP is cool

My guess is, the motor is just tired, Valve seals and probably rings.
I had a 67 yrs ago that did the same thing. Blowby so bad it would come
in the cab, and no smoke to speak of out the exhaust. FE motors
at least mine have needed valves seals in the past.
Good Luck

Might want to do a leakdown check on it to give a good indication of it's condition. I'm with shoprat on the old and tired diagnosis!!!!!!

Thanks for the info guys... It may be tired don't know it history very well...i will check the drains this afternoon...it does not smoke at startup at all, only after running a min or so.. we did put a new valve cover breather on the drivers side but it is blowing through the breather.

I was just told by a local to change the drivers side breather to a PCV breather and tee the vac line from the pass side to the carb plate and run lines from both to the plate. This has stopped the smoke under the hood completely. It still seems to run fine just no smoke. The oil and filter were just changed a few days ago. Thanks for the help DennyW.

Originally Posted by DennyW

If it's not smoking out the tail pipe, and the PCV valve is working, you need to pull the valve covers, and check the oil drains in the head. Also, if it smokes when you first start it up, that is an indication that the valve seals are probably bad. That, along with plugged oil drains will cause this. Also, if the drains are plugged, the PCV valve cannot pull the vapors from the opposite side. Which causes smoking (blowby) to continue coming out the valve cover. And make sure the breather side breather is clean.

DennyW, can you please tell me where on the heads I can find the oil drains on a FE 390? is there more than one per side? What would be the best way to clean the drain? Maybe with a rod and some Seafoam?
TIA

I have to ask...................how do you do yours????

DennyW, your the man Thanks for the pix, that was awesome of you. I think my drain holes may need to be cleaned I may go look for those brushes they use to clean gun barrels with??? What do you think of doing a Seafoam motor flush? Bad idea?
TIA