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Discussion Starter #1
I am trouble shooting an oil leak from the grommet around the PCV. It does not leak all the time and it does not leak very much, but it is annoying.

I have a SBC 383. I have a breather on the right side and a PCV value on the left side.

The PCV value is connected back to the carb.

Both are new, less than 500 miles.

The breather is a K&N and the grommet for the breather has a slit in the bottom that acts as a baffle. I checked the breather and is seems to be working fine.. (it took me a while to get the oil off my lips :) ).

One guess is at higher RPM the pressure in the crankcase builds up and actually forces the rubber baffle in the breather grommet to close. The weakest point is the grommet on the PCV value.

Anyone have a similar problem?
 

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Discussion Starter #3
Bill, there is no baffle built into the valve cover. The grommet has a rubber floor that seems to work like a baffle. My thought is if that was the problem the oil would not wind up on the valve cover it would be sucked into the carb.
 

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Are they morosos?Their bafflegrommets open up to let more oil thru on high rpm driving.
I was running a set of blue morosos on my 454,no baffles.Was sucking oil thru the pvc and sending it thru the plugs.You couldnt see it or smell it though as it was only happening on high rpm driving,something to do with,I was told,the low tension metric rings gm uses in my gen VI.
I wound up making a set of low profile,wide metal baffles and riveting plus black rtv-ing them into the morosos.Works good now.
For loose hole stamps in the covers I clean well and black rtv the grommet in.
 

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Discussion Starter #5
Not K&N.. I think it is Mr Gasket, I checked the part, there is no mfg name on it.

The oil is leaking between the grommet for the PCV and the valve cover. It is a tight seal, I am worried if I make the seal tighter by using silicone I will not have fixed the problem, just moved the weakest link like to the oil pan gasket.

You can see the baffle on the breather grommet, not sure if that is the problem. But I am suspecting it is closing up when high positive pressure is in the crankcase.
 

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Try removing the breather and see if air is entering the engine. A small piece of paper moved over the hole should let you see if air is entering or leaving the engine. You should have air entering.

Those billet breathers can be a problem as well. Sometimes the screen is so fine that almost no air will enter through them.

I would also split those 2 vacuum connections into individual lines. 1 to the carb for PCV and 1 to the intake for the brakes.

Those rubber baffles can be a problem if there is no baffle in the valve cover itself. The rockers spray oil at the PCV inlet and oil will migrate into the PCV and around the grommet.
 

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Discussion Starter #8
Chris, one end goes to the carb, the other end goes to the power brakes.

Thanks Levon.. I will try the test with a paper over the breather.
I am not sure if I have 2 ports on my carb, I will check.
The valve train is solid lifters and roller rockers. The cam is a street/strip cam so I am sure there is a lot of oil splashed around inside.

The leak is very minor and I can live with it, but it is annoying. I wonder if there is a better grommet that would still act as a baffle. There is no baffle in the valve covers.
 

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Wouldnt then,your power booster have oil from the pvc in it?I'd def. seperate them also.Usually power brakes need a manifold port to run good.
Those grommet baffles are prolly letting you down also.Thats a big hole on the one you picced.
Even with my baffles I made,I still run a moroso air/oil seperator and still get some in it.Its on the firewall,to the left.




 

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Discussion Starter #10
Thanks Chris. I will check to see if I have oil in the vacuum line going to the power brakes. I assumed (likely incorrectly) the PCV valve would have a 1 way valve that would suck air out, but not let anything in. I do not have a vacuum port in my intake manifold (Victor Jr). I do have a spacer that goes under the carb that has a vacuum port, but I am not sure I have the clearance to install it. I need a low profile air cleaner so my hood would close.
 

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x2 Definitely get that PCV on its own dedicated line back to the carb. Keep the booster on a clean vac line shared by other components. Aside from contamination, you'll actually lose break assist at times the PCV is in operation.
 

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make the baffled grommets into regular grommets, keep the K&N breather on one side, and put a Mopar style breather in the other side with the pcv in line after that..
 
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