fly boy_1

iTrader: (4)

What could cause a turbo to randomly start smoking? I've got a turbonetics 7875, and its been down for about 2 months or so due to a trans problem. Before it would ocassionaly get a random puff of smoke due to the less than idea oil drain (on3) turbo kit.

Got it all back together and took it for a test drive tonight, and after about 5 mins of driving I noticed the turbo started to smoke which seemed to get progressively worse on the short ride back home. Any ideas what would cause that when it was fine before the rebuild? None of the hotside parts were touched at all, I'm at a loss on what would make that happen? I'm used to my stuff taking a **** on me so I'm wondering if the oil seals in the turbo went bad from sitting somehow? Car makes good oil pressure, 40-45psi at idleup to 60 when running, did not make any pulls on it all normal driving.

95bowtie

How's ur pcv setup? There must be no crankcase pressure. That will cause the oil to not drain very good.

I had the same turbo with the drain line going straight down into the pan. The turbo was mounted up high next to the valve cover so it had plenty of gravity. But when my breather tank got full of blow by oil and water the turbo would let me know right away. It would start to smoke.

mfast1

Does it only smoke under load at idle or both?

stevieturbo

The turbo is smoking, or you are seeing smoke out the exhaust ? The two are not the same.

fly boy_1

iTrader: (4)

The car has the mighty mouse race style catch can, I havent checked to see if its full. There is oil in the downpipe, which Id assumed is from oil being forced past the seals for an unknown reason. Its smoking both at idle and while cruising. I havent seen oil anywhere except in the dp so far.

stevieturbo

There are no seals to force past.

Check oil drain is good, and ensure crankcase breathing is good.

Orr89rocz

iTrader: (13)

What keeps oil in the bearing and not coming out the exhaust or compressor then?

If it doesnt drain it willl go into the exhaust. Turbos do have a seal

stevieturbo

Turbos do not have an oil seal.


http://www.yellowbullet.com/forum/sh...d.php?t=837618

fly boy_1

iTrader: (4)

Im gonna have to pull the drain, and hopefully find a blockage there. What baffles me if the sudden onset of smoking when there was none and no sort of catastrophic failure either.

fly boy_1

iTrader: (4)

If the drain is clear is it safe to try something like seafoam to try and clean the seals out?

Orr89rocz

iTrader: (13)

You just proved my point they have a piston ring seal around the bearing. Did you even read that post? It does some to keep oil in. It has tight tolerance in there. Some other turbos like small garretts use seal plates they call it

stevieturbo

The piston ring is a gas seal to prevent either boost pressure or exhaust gases entering the bearing core. It is not an oil seal to prevent oil escaping.

Not sure the arrangement in BB turbos though, they may well have seals of some description.

mfast1

Did you check shaft play in the turbo? If catch cans and pvc it in good working order then it's probably a turbo issue.

fly boy_1

iTrader: (4)

There is some shaft play but it had some when new as its a bb but that was so long ago I cant tell what would be normal anymore. Im going to attempt to reclock it and try to impliment a superior drain set up. With such low mileage Id find it hard to believe its a seal going already, maybe a defect of some sort internally.