White smoke coming out of the Catch Can while idle.

Hey guys i have a built NSX motor with the BBSC running 10lbs. My Catch can is vented in the engine bay and has white smoke come out at idle. Once i get moving the white smoke goes away. I talked to one performance shop they said the build could be .000001 loose and could cause the white smoke and i dont need to worry since the compression and leakdown came out perfect.

Anyone else have this issue? im thinking about re-circulating the catch can back into the motor.

I had a great thread about catch cans but from my perspective you need to just keep an eye on it. When you're driving around you'll notice there's more air moving around so the white smoke could be swirling around, look carefully. When I accelerate there's also more then when just idling.

Just keep an eye on it. I know people running huge catch cans and not having issues and some running just tiny little filters right off the valve covers... All builds are different and also I believe someone mentioned weather conditions matter too.

Mine is currently doing that but there is more coming out when on throttle. Don't know what it is yet didn't get a leakdown or compression test yet. Motor is stock.... 9 lbs boost

Do a compression test. If all is good it's just normal blow by and moisture in oil evaporating.

If you have an outlier or two, possibly busted ringland.

Does your car have a scavenge pump on it to return the oil to the engine?

Triet, I'm not sure I've seen a built motor NSX with a catch can setup not have some "smoke" coming from an aftermarket catch can. Actually, even non built with a catch can does this in my experience. Non FI cars/owners don't usually do a catch can, so would never really notice this so I'd venture to guess, all NSX's do this?..

mrbozo1 said:

Does your car have a scavenge pump on it to return the oil to the engine?

Click to expand...

No, it's a bbsc with the drain going directly to the oil pan if I remember correctly.

oops my bad for thinking that your car was turbo. Did not read your whole first post.

There's a difference between white smoke and water vapor. Some catch cans will emit a white looking vapor, which is mostly oil and water vapor, that looks a bit like smoke (like an e-cigarette). However, this is normal and for the most part harmless. It may make your engine bay a little cloudy, oily or smelly. You'll know it's vapor in that it should dissipate very quickly, again, like an e-cigarette.

White smoke on the other hand is sign of larger problems, such as engine damage, piston blow by, burning oil etc. If your engine is having problems the tale tell sign is white smoke either from the oil catch can breather or exhaust. This smoke usually does not dissipate as quickly and will have a stronger burning odor. The smoke will also look denser or cloudier. If you suspect smoke, and not water vapor, you should do an analysis on your engine integrity, like a leakdown or compression test to see if you have any engine damage.

thanks vegas!

its more like your first answer
"There's a difference between white smoke and water vapor. Some catch cans will emit a white looking vapor, which is mostly oil and water vapor, that looks a bit like smoke (like an e-cigarette). However, this is normal and for the most part harmless. It may make your engine bay a little cloudy, oily or smelly. You'll know it's vapor in that it should dissipate very quickly, again, like an e-cigarette."