hey mopar fourms I have a 1965 plymouth with the 383 big block i have got it running but noticed a lot of crankcase exaust coming from valve covers vent when i put the oil cap on left valve cover it started to push oil out rear main seal but when i removed the cap it stoped it sounds like headgasket or piston ring blow by not sure about mopar if someone could point me in the right direction what to look for thanks

 

Welcome aboard. Could be piston blow by caused by weak piston rings. It will cause excessive crank case pressure.

 

Sounds like time for a rebuild

 

welcome to the forum

 

It ALSO could be that the breather could be all gummed up, and or the PCV valve plugged. If the engine does not smoke out the exhaust, this might be the case.

Spend some time looking this over. You should have a PCV valve on one valve cover, going to the carb, and a breather on the other side. I don't think, that in 65, the breather was connected to the air cleaner bonnet, but rather just open.

You should have a good vacuum against your finger if you pull the pcv out of the valve cover, with engine idleing.

 

Welcome to the forum... Listen to 440 roadrunner he has valid points for you to check before you get involved in a re-build... Also, be sure to check out the Mopar of the Month contest.. See the sticky for the simple rules and then you can help choose the winner.....

 

Welcome kdykes hope you enjoy it here and check out what all is saying about your engine , also to me sounds like a poor breather had that happen to me as well

 

Welcome!