BLOWING OIL FROM BREATHER AFTER HEAD CHANGE

[outlaw66]

I repla ced the heads on my 289 last weekend with some Jegs 58cc aluminum heads, and Crane roller rockers. Now I'm blowing oil out the breather to the point it's wetting my valve cover and master cylinder. The engine never blew oil with the steel heads and Erson roller rockers that were replaced. Engine has 450 miles since rebuild and runs fine. The oil blowing is definitely a reaction to changing heads and roller rockers. I read previous threads on this subject but none addressed breather oiling after a head change. Is it possible that the pushrods are never being sealed off during valve train operation by the new rockers and are constantly oiling. I do have a high volumn oil pump and the same oil pressure but did not have this problem until i changed the heads.
Any help appreciated.

Outlaw66

 

[302 coupe]

I would doubt its a result of the rockers or pushrods. Even if the pushrod length were way off, the oil holes would still 'mesh' properly. Theoretically, the performance increase due to increased air and fuel flow, resulting in increased cylinder pressure, would create more blow-by for any given cylinder seal. Thus an increase in crankcase air pressure, which would push more air/oil vapor out of the breathers. As a side note, valve covers need to have a baffle to prevent splash oiling through the breathers, so check that out. Also, check your valve cover gaskets to make sure they are seated properly. I recently switched to some RHS heads and I've noticed more oil on the valve covers too, I attribute it to me pushing the engine harder, its sees alot more rpm now than it used to. At any rate, assuming you don't have any compression/leakdown issues, you can replace the breather with a hose fitting, then run a piece of hose to a remote mounted catch can, and fit the catch can with a breather for ventilation.

Actually, thats something I've been meangn to do for a while now. I want to relocate the breather and PCV valve and go to a catch can setup. Running a PCV valve on the valve cover can really gum up a manifold and the intake valves as well. They always suck up a certain amount of oil, I think with a catch can the system would be much cleaner.

 

[mustangbrad]

I'm with "302 coupe". I'll bet your problem is blow by. I rebulit my stock heads and replaced the cam with a mild aftermarket cam, now blow by is a big problem. Enough so that I am going to have to rering the egine.

 

[bdepedro]

I rebuilt my 289 this year and have also been having some oil pushed through the pvc valve. In my case the valve covers I have do not have a baffle at the pvc outlet so I'm going to replace the covers and that should take care of it. I have the Cobra finned covers but I don't know if they all are like that or someone removed the baffle on mine. The amount of oil I am getting is very little so that's probably not what you have going on though it's easy to check and it could be adding to your problems if you have the same thing.

 

[GoinBroke]

I would not freak out by the blow by.

 

[GoinBroke]

I would not freak out by the blow by. If the engine is running Ok and has the miles you have given it is just where the rings are not seated yet. Give it to around 1K miles to breakin the engine and seat the rings before you do anything rash. Speaking of rash the last post was rash also!

 

[outlaw66]

302 coupe,
I think you hit it on the head. The Moroso valve covers do not have a baffle under the breather. I remember seeing some SCCA cars with some plumbing between valve covers, and I suppose that was to prevent the same thing due to increased crankcase pressures. You're correct in that I did run the car a little harder which I'm sure didn;t help, but thats what they're for right?

Has anyone got any "catch-can" pics I can checkout? Sounds like that may be the way to go.
I'm certain the engine is tight as it performs well and like I said only has 450 or so miles on it since I rebuilt it.

Thanks all you guys for your responses.
I really like the idea of a catch can. I remember Historic said he had installed one on his race car and even then, when operating at those RPM's for extended periods, they all tend to "oil" the engine bay.

I'll check Historics site and see if he has any pics posted that I can get some ideas.

Outlaw

 

[bdepedro]

Yeah, I'd also like to see pics of or know where to buy an oil catch can. Summit maybe?

Break-in smoke out the exhaust is what made me realize I was blowing oil through my pvc. The rings used in my engine rebuild are very hard and took a while to seat, about 1500 miles, during which I was getting smoke under hard accel. I thought it might be all blow by but the guy who rebuilt me engine said it was normal with my rings and the amount of oil in the pvc line was minimal. I don't get any smoke now but I might change to valve covers with a baffle.

I appreciate the heads up on the Morrosos, I didn't know they didn't have a baffle.

 

[mustangdave]

Just a note: you can run valve covers with baffles. If they don't clear your rockers, there are spacer plates you can install to raise the covers.

 

[bdepedro]

Just a note: you can run valve covers with baffles. If they don't clear your rockers, there are spacer plates you can install to raise the covers.

Thanks for the info Dave, I plan to change covers to ones w/ baffle and I don't think I should have any valve clearance issues. I was planning on using blue anodizd Morosso covers to match my air cleaner but I'll have to check to see if they come w/ baffles.

 

[brin0357]

Look at any "Race" car for catch can ideas. american iron scca or other types and you will see catch cans on all of them

 

[bdepedro]

I'll try that but I don't get to the track often and when I did it was SCCA racing and most of those guys build their own cars on a very tight budget so most catch cans were previously used by Juan Valdez. Any reason one of those nice alum cooling system overflow bottles wouldn't work?

 

[SoCalCruising]

Try:
http://www.stefs.com/products/drysumptanks/overflow&breathertank.htm
Everything you need ....

 

[bdepedro]

Thanks, that looks exactly what I need. I haven't yet but this would be a good time to swap my plastic cooling system overflow bottle with a matching alum one.