Smoke out the breathers

psycho6cyl

Ponies Are For Lil Girls
This is a fresh build with under 2k miles on it. No reported knock maybe max was 25psi with Alky. I seem to have intermittent smoke out the catch can for breather. Haven't pulled plugs or anything yet. Car runs like a top. Oil is not milky and haven't lost coolant. It was smoking like this on jack stands. Also the car is not running a pcv if that makes a difference. Seems to be smoking on both valve covers..
 

ITSAV6

It's my Granny's car!
you have a catch can? or just breathers? you could perform a leakdown test to rule out blowby. why no pcv?
 

psycho6cyl

Ponies Are For Lil Girls
iI have push in an fitting to catch can. Only have one going to catch can. Pass side is plugged for now. Took off plug and making smoke that side as well. Didn't seem as bad. Builder said to not run a pcv and plugged it
 

earlbrown

runs with scissors
Time for a leak down test. You need one anyway for a baseline.

Mine smoked like that when I cracked a piston.
 

psycho6cyl

Ponies Are For Lil Girls
Well actually spoke to builder and he said:

Smoke out of the breather can is normal, especially when the ambient air is cooler and humid(hot from the engine and cold ambient air temps causing a condensation effect). The heat from the oil combined with combustion heat/vapor, is what usually comes out of the can. When someone is used to engines with pcv valves, those vapors get sucked back into the intake via the pcv, so you dont get quite as much vapors out of the breather tanks. The only time for concern out of the breathers, is if the smoke is literally being pumped out of the breathers with pretty good pressure.
 

earlbrown

runs with scissors
Well actually spoke to builder and he said:

Smoke out of the breather can is normal, especially when the ambient air is cooler and humid(hot from the engine and cold ambient air temps causing a condensation effect). .


That's called steam. Different animal there.
 

earlbrown

runs with scissors
I do. My chip expects the metered air leak and my check valve keeps boost from hitting the valve.


There's no performance downside and it keep the inside of my engine more sanitary.
 

BARRACUDA1968

Well-Known Member
So if I'm reading this right that's the only breather on the motor right now? If the oil is real hot I can see a little oil vapor coming out a breather but that seems like a lot unless maybe that's the only escape out of your motor.

I disagree about not running a PCV especially on a street car but to each his own.
 

WHTTRSH

Sleeper
Mine do the same w a ton of baffles too under the covers. I actually have oil dripping from the breathers and onto my valve covers. My engine has less then 1k miles on it. Dan Strezo at DLS built the engine and installed CP-Carrillo pistons. Hopefully it breaks in better after another 1k miles on SAE30W break in oil... I'm trying to get my hands on new covers though and have -12AN fittings welded in to run a Moroso catch can. Eliminating the breathers
 

TurboBuRick

Moderator
Staff member
The piston brand has nothing to do with blow by.

Jack Cotton sells AN fittings that push into the valve cover grommets.
 

WHTTRSH

Sleeper
Sure any normal person would think that. However I witnessed first hand four engine builds w CP Pistons have blow by issues due to a manufacturer defect. Found the rings were not made thick enough so the rings never sealed. CP blamed the rings and the manufacturer of the rings blamed CP. We had new rings made and went with JE pistons, blow by was gone. These were motorcycle applications, however they still were Carrillo Pistons.
 
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TurboBuRick

Moderator
Staff member
So the rings glands being cut to deep causes excessive blow by?? Interesting to say the least. I would think the width of the glands would be more crital. Defiantly food for thought.
 

ttypewhite

Well-Known Member
I would run the pcv along with the valve cover breathers, it will reduce the smoke from the breathers alot.
 
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