Hey guys, I have 2003 Z with a custom gt35r turbo on it It's smoking from exhaust at all times. The turbo has 600 miles on it... as an experiment I loosened my oil cap and the car stopped smoking... long story short I ended up loosing the oil cap. No big deal only lost like a 1/4 of quart of oil. got another cap and now it smoking more then ever... I did do a compression test and that passed with flying colors. I have heard of vented oil cap but can't find one. Any help would be much appreciated! oh btw I have a cusco oil catch can on it between the cross over on the valve covers.. If you have any cocky answers or plan on downgrading my post, do me a favor and keep your comments to yourself! also don't even attempt to tell me to use the search button, because I have for the past few weeks... Thanks guys!

 

once you start smoking, its hard to quit. Hopefully your Z doesn't get lung cancer

 

did you check and see if your pcv valve is good?

 

Had the exact issue recently. The PCV system was not working correctly. I was looking into a catch cans and decided to check my charge pipe for oil. She was as dry as could be and that led me to believe that I wasn't having blow by. So long story short, I have a cracked vacumn line and a nipple cover that had been sliced. Replaced both that to tighten up any vacumn leaks and problem solved, giant cloud of smoke no more.

I would go through all your vacumn lines and anything that's tied with your boost/ vacumn sources first to see if there are any leaks.

 

PCV seems to be doing what it's suppose to. I physically inspected the valve its self. I've heard of people running another check valve in line after the original PCV.... Also, I've heard of people drilling out the PCV completely; capping off the intake; running the hollowed out PCV to one side of a vented and baffled catch can; then running the other side of the can to the rear of the drivers side valve cover. Also I hear a lot of turbo guys don't even run catch cans...

 

is it black/grayish smoke or white/bluish smoke. If it is the latter then your turbo seal is gone because the heat of the exhaust is burning up the oil.

Hypothesis: I would say that is your seal is gone because in the pressurized system the oil is seeping through the turbo seal but when you loosen the cap the oil is not pressurized and not "forcing" it's way to the exhaust side. I know you said the turbo only has 600 miles on it, but was it rebuilt or ever used?

Oil system experts please chime in and let me know if I am full of it.

 

It is white/bluish smoke, it's def oil burning. And yes the turbo is brand new never used.

 

are you able to easily check the exhaust side of the turbo to see if there is oil buildup?

 

If the turbo is indeed leaking oil (causing it to burn too) then you will have oil build up right where you down pipe comes off the turbo. Pull that like Suprasam stated and that will give you a good idea if it is indeed the turbo or not.

Another quick question that I have is what kind of oil are your running?

 

Mobile 1 5-30

 

Catch can or not, if you have the stock style pcv setup where the crankcase cases go into the plenum then you will suck oil vapors into your manifold. It would have to be a significant amount of oil to cause it to smoke coming in from the manifold. I know when I was running stock block FI I took my plenum off and it was covered with oil (it was pooling in the plenum) due to the stock pcv system. I never once had any smoke from my exhaust. Due to that it makes me think the oil is coming from the turbo.

What is your oil drain system like on your custom setup? gravity feed or sump pump? If you do'nt have a reservoir on a pump system then when you turn the car off oil will seep past the seals and get into the turbine then smoke a lot. If you have a gravity feed it might not be large enough and cause oil backup.

 

Its a gravity set up. I have a -3 oil feed with a .035 oil restrictior and I have a 5/8 oil drain. The drain is a straight shot with out any kinks or bends. I am using an oil pan spacer and that's where the drain line is going to. Someone told me that might be an issue, But i don't see how that's possible...

 

What size is that? 10an on that sized turbo is recommended so if 5/8" is 10an then that size is ok. The oil pan spacer is probably the issue. Since you are returning oil below the level of oil it won't flow freely into the crankcase. It specifically says on all gravity feed systems that the oil return my return oil above the level of oil in the crankcase to prevent restriction. I know a lot of vortech owners don't follow this rule but there is a huge difference in oil returning from a turbo than there is from the tiny spray nozzle feeding the gears of a super charger.

also, the center section of the turbo must be vertical or no greater than 15* angle from vertical to allow the proper draining of the bearing area. If it's tiled on an angle it will retain oil in the center section of the turbo.