Inliners International Forums General Discussion Engines Oil Shooting from Breathers

I have had some oil coming out of my valve cover breathers. I have three brethers on the motor. Only the breahter closest to the front (radiator) is blowing oil. I have had no performance problems and have had good oil pressure and tempurature. Also - good water tempurature. Should I worry? This is a dirt trrack race engine. Should I worry?

Not knowing what sort of crankcase ventilation system is on the motor makes it kind of difficult to make suggestions.

Does the engine even have a PCV system? That is, does it have a PCV valve and hose connected to the intake manifold or carburetor base? A lot of off-road race engine builders don't use them at all. Instead they install breathers in the valve covers. The result is a design that is similar to a road draft tube. Any excess pressure in the motor is vented through the breathers, and if there is a lot of oil mist (droplets) carried with it, then it appears on the outside as an oil leak.

If you really want, you can take the valve cover off and inspect the base of the front breather. All of the breathers should have some sort of deflector plate to keep oil from splashing directly on, or into, the base. If they don't, then you may have to fabricate something to keep that splash oil from coming up through the unit.

Give a holler if you've got any questions.

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David
newbie #4153

I'm having the same problem in my 67 1/2 ton. I have one of those aftermarket chrome ones which vents from the bottom. I do alot of hwy miles and find lots of oil spray all over the valve cover. Here's the kicker, it had the original oil fill cover, but on the recommendation of the guy who replaced my rear main seal-it was replaced. The wierd part is that my Camaro is the exact same design and it regularly sees high rpms and I've never had a problem blowing out the rear main seal.

I too, am wondering if there's a breather that won't blow oil out the bottom.

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67 Chevy truck 250(no, I'm not putting in a 350!)
68 Camaro 250(again, I'm not putting in a 350!)

Brad,

I'm assuming you still have a stock intake manifold on your truck? One of the problems with stock intakes is their tendency to plug up the PCV tube that pokes into the center intake runner. If that pipe is restricted, then excess pressure will build in your motor any time the rpm's get up high. On numerous engines I've had to remove that pipe and plug it from the top, and then drill and tap an extra hole in the intake right under the carb for a new fitting where the PCV gets plumbed. The early motors had that configuration from the factory; I've still got one on my original '63 292 1-bbl manifold (on a shelf though).

If there is excess pressure from whatever source, the motor is going to relieve it someplace. A vented breather cap is the easiest place to come out, so that's usually where you'll get an oil "leak".

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David
newbie #4153

Thanks David. I hadn't thought of that. The next time I'm near my truck, I'll look into it.

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67 Chevy truck 250(No, I'm not putting in a 350!)
68 Camaro 250(Again, I'm not putting in a 350!)