fe390 oil leaks after pcv connection.

[prdjr1]

I installed a recently rebuilt fe390,I ran it without a pcv valve for about 100 miles.I then connected thr pcv valve and the engine ran slightly rough but I didn't think much about it.The next day i noticed an oil leak from the front crankshaft seal and the intake gasket.What could be goiong on ?The pcv valve is good and i also tried a new one after replacing the intake gasket.The engine is a stock rebuild nothing fancy.The carb is a 600cfm holley and the driver side valve cover hose is connected to the air filter housing.

[cep62]

Well a pcv is basically a controlled vacuum leak. If you set the carb without it it may alter the idle.
And 100 miles isn't enough to seat the rings so there may be some crankcase pressure. Maybe.
Does it draw a vacuum when it's running ? put a finger over the end when it's running to be sure.

[prdjr1]

should i run without a pcv valve till the rings are seated ?

[cep62]

No , it should still be used to evacuate the crank case.
You do have a breather type oil fill cap don't you.
It lets air in so the pcv can do it's job.

[prdjr1]

I do have a vented cap on the drivers side,why is this happening ?

[DuckRyder]

Id put an open cap on the fill side for a while.

Does it stop leaking if you open the system?

Where exactly is the intake leaking?

[prdjr1]

it doesn't leak without the pcv installed. intake started leaking at the rear of the china wall.

[brkdncr]

Your gasket is bad. The vacuum may be pulling it in far enough for it to leak.