Blow-by smoke

[Sandy_C]

I got a brand new BB engine and am now seeing blow-by smoke coming out of the crankcase vents on top of the valve covers. This engine has less than 1000 miles on it. There is no PCV valve system, just a filtered vent out the top of the valve covers. A guy who is troubleshooting the problem is coming out tomorrow to put a flowmeter on the vent to see if the blow-by is excessive. Personally I don't care what the flowmeter says, having oily smoke fill your engine compartment with crud and having smoke coming out of your hood scoop at a stoplight is not acceptable. Am I out of line here? What is a normal reading from a flowmeter when checking blow-by? Should there be any blow-by smoke at all? The engine seems to be operating normally with no noticable (by the seat of the pants) loss of power. There was no blow-by smoke when the engine was brand new but now there is, I suspect a ring/piston/cylinder problem where a tear-down is required to troubleshoot and fix. Comments, ideas?

[Bob Cowan]

Some blow-by is normal. You can't avoid it. That's the purpose of a PCV system, to keep those fumes out of the air. I don't have a PCV system. But mine are plumbed directly into a catch can. No fumes, no oil drips.

New engines that have not fully seated the rings yet will have a lot of it. What rings, assembly lube, and oil are you using?

Never used a meter, I never knew they existed. So I don't really know about that.

[Racer 28]

A Cylinder Leakdown Test will tell you how much and where your blow-by is. It gives you a percentage of leakage in each Cylinder with compressed air, you might try asking Gordon about how much percentage a BB is supposed to have, a small block with 1000 miles new should be between 5 and 12 ideally with a variance of no more then 5% between each cylinder. Make sure if the engine is new and not dyno broken in, that you run a non-synthetic engine oil for at least 1000 miles before switching.

[Gordon Levy]

Give me a call at 520-494-2745. I am only 30 minutes from you and can help. Gordon

[Sandy_C]

Thanks Gordon, I stopped by your place a year or so ago and I was like a kid in a candy store! This engine is still under warranty and I want to see how the builder handles it before I do something without permission that might void the warranty. I will definitely give you a call if they don't take care of it. Thanks so much, nice to know you're there.

[98Aggie]

Sounds like the builder didn't set the rings right, has one upside down or something. It shouldn't smoke.