First of all, this is the first turbo car I've owned so I'm new to turbo stuff. I recently traded for a truck that has a turbo LQ4. This LQ4 was supposedly just rebuilt and only has 7k miles on it. It has a vented catch can setup, and I noticed the other night when I got out of the truck that it was smoking, as I could see it in the headlights. I drove it again the other day and then looked under the hood and smoke was coming out of the vent on the catch can. It doesn't smoke one bit when cold started though. I guess only after I drive it for a bit.

Is this normal for a vented catch can? Also, sorry for the stupid question, but does a vented catch can still collect oil, or is it all vented to atmosphere? Because the catch can was empty when I checked it.

 

A little bit is normal.

 

Yea a little bit of steam/smoke is normal. Its mainly just water vaporizing off. Depends how much blow by you have to how much oil and stuff will be in the can.

 

this is spot on.

 

What would be considered a little bit, or an acceptable amount? Mine didn't steam at all when I cold started it and it has no oil in the can, but after I've driven it I've noticed the steam steadily coming out of the vent on the can. It may not be any big deal, I just don't know how much steam is considered a little bit.

 

Ya know when you are boiling water on the stove and right before the bubbles start appearing its steaming a little bit? About that much.

 

Okay. It's probably alright then because that's about how much was coming out. It wasn't billowing out or anything, but steady enough that when I popped the hood and smoke/steam was rolling out, it looked like something was wrong lol.

 

On that note, would you guys recommend a sealed catch can setup or keep the vent to atmosphere?

 

If it's coming out in pulses, then you have a problem.

 

It wasn't, actually. It was just steadily coming out of the vent. And actually, I was just thinking, both times I noticed the steam/smoke, it was after only a short couple mile drive to a buddies house and then I parked it, so maybe it didn't have time to evaporate all the water in that short amount of time? Maybe I'm just paranoid lol