Oil leak from the valve cover seal and spark plug seals

[Lextreme II]

Got the car out last night around 12 am and drove about 60 miles. The goal was to push the car and try to blow out all the junk oil/water in my exhaust. The car been smoking and best way to do it is at night with minimum traffic. After boosting have dozen of times the smoke finally gone.

Anyway, the half dozen boost was about 5.5k to 6k rpm and reach 12.75 psi max with 1 bar wastegate spring. The car pulls hard on the freeway. Currently i have the stock PCV tube from valve cover to the intake. Please pic below. Would this is the problem for the oil leak due to increase crank pressure? Should i use a oil breather? Second picture is my old setup with oil breather.

 

[stevechumo]

Using the oil breather could solve the problem. If there's too much oil leaking, it could be due to the piston rings are leaking. I had this problem before on my turbocharged Honda. I blew the first cylinder's piston and rings with too much boost and the oil came out crazily from the breather, and also through the downpipe flange and to the exhaust. So if I had no breather, then the oil would also find its way to the intake. Here's the link of trouble shooting for the turbo oil leakage: http://www.turbocity.com/documents/TurbochargerTroubleshootingMatrix.pdf.
Anyway, I hope this is not your problem. Perhaps the turbo oil seal is leaking.

 

[Toysrme]

Route both PCV & any crnak case breather to either a vacuum pump, or a pre-turbo sorce of vacuum. Yes... I know you have no intake, but buy a flange for the turbo with vacuum ports, or make one & put some nipples:smileysex on it!


Vaccum > Breather. I've heard that ring blow-by triples once you're running anything more than low boost. Tho I can't verrify that, it seems right, as most engine's given very little time will have tons of blow-by as the crankcase builds pressure.

 

[cribbj]

Many of us with Supras will run a system with a catch can, routed like this:

Crankcase vents----->Catch Can---->Intake (preturbo)

The catch can keeps the "caught" oil from fouling the intake tract.

Wish we had some of the better air/oil separators that I've seen fabbed in Australia from articles in AutoSpeed. Our catch cans in the US are just simple inline pots.

 

[krayn]

David,
My engine may be a little different to yours but on mine there are two valve cover breathers that enter the intake plenum, the one you have shown and also one the enters the bottom of the throttle body. I disconnected both mine and pluged the holes into the plenum and fitted a breather on both. The one on the rhs( your passenger side ) will req a length of hose to a remote breather. kris

 

[Lextreme II]

Ok,

Got the oil breather now. Looks like its alot less pressure from the engine crank. We also check the circular plug behind the camshaft. It was blown out and oil is leaking from there. Not a big deal. With the intake PCV plugged and it should be ok. See below diagrams....

 

[Toysrme]

I don't know, I've never been a fan of catch cans. Tho they're very common place & do work, it's just a substitute for actually fixing a problem. As in taking a valve cover off & making / modifying the baffle so that oil doesn't get slung in the breather in the first place. There's really not much too it & it's always fun to re-engineer something that 30,000 engineers with degrees got wrong in the first place LoL!

Especially since JB weld & a piece of sheet metal with at most a few holes drilled in it cost nothing.



The circular plug for my intake camshaft w' the distributor on it (on my v6) has always leaked, even after installing a new one! After cleaning it with acetone, I finally got pissed & put a bead of RTV before it. Problem solved!

 

[cribbj]

Another interesting solution to crankcase venting:

http://www.krankvent.com/

I've been looking at these things for years, but never used one. One of my buds who runs a DSM website swears by his.

Anyone here tried one?

John

 

[Lextreme II]

What happened to my setup was that the stock PCV didnt fully block out the boost pressure and reversed into the crank and pressure build up. I wonder if i change to a new PCV would solve the problem. Right now I am using an oil breather and the problem is solved, but i still have slight oil vapor via the oil breather.

 

[cjsupra90]

any time that you turbo a motor, you should always route the PCV lines preturbo. the reason for the PCV valve is in the event of a backfire it doesnt risk one hell of an explosion in the crank case being that there is volital vapors in the crankcase. using a PCV valve to block boost and not allow any release if crakecase pressure is not good and you do risk blowing out seals and creating leaks. I think that one of the best PCV systems is what Toyota used on the 7M-GTE motors (not sure if used on other factory turbo's also), its a 2 stage system so to speek. Basicly it routed to the intake during non boosted situations and as the manifold vacuum drops, it kicks over to a track that is in the intake pipe into the turbo that way the crankcase is always exposed to a vacuum source regardless of weather or not the motor is under boost.

 

[cribbj]

Ummm, not exactly.... The 2JZ-GTE (JZA80 Supra) does have its PCV valve located between the intake valve cover and the intake manifold. Post turbo in other words. Are you sure your 7M is different from this?

There is another vent on the exhaust side valve cover that routes back preturbo as you suggest.

There is also a small hose that connects the two valve covers together, so blowby from both valve covers can use the PCV route (negative manifold pressure), or the exhaust side vent (under boost).

 

[cjsupra90]

Ummm, not exactly.... The 2JZ-GTE (JZA80 Supra) does have its PCV valve located between the intake valve cover and the intake manifold. Post turbo in other words. Are you sure your 7M is different from this?

There is another vent on the exhaust side valve cover that routes back preturbo as you suggest.

There is also a small hose that connects the two valve covers together, so blowby from both valve covers can use the PCV route (negative manifold pressure), or the exhaust side vent (under boost).

That is exactly what I said. sorry that I forgot to mention that there is a valve in the 2stage setup. yes the 7M is slightly different, but the principle is the same. ok, yes the valve is blocking boost from entering the crankcase, but because of the other vent, the crankcase still has a vent path and when under boost, the intake pipe preturbo is going to be in a slight vacuum. it becomes a very good vent path not to mention that when under boost, the crankcase would be experiancing the highest of pressures. Either which way, the way that Dave (Lex) had it set up when he goes under boost, the crankcase would become totally sealed and then therefor would start to experiance positive pressure which as we all know is a bad thing. To make matters even worse and I dont know if all of the motors have this, but the 92 SC400 motor that I have in my shop getting ready to go into my supra has a vent connection under the throttle body that goes to the right valve cover that has no valse of any sort and if being used, will allow the crankcase to experiance boost pressure when under boost just to let anyone know that does't already know this.

 

[cribbj]

FWIW, here's the 7M-GTE PCV diagram, taken from the Factory Service Manual. Both valve covers are vented to a PCV "hose", which then is routed to a point just before the TB, post turbo.

Interestingly, this PVC "hose" is built like a Tee, and its other leg goes to the intake, pre-turbo as cjsupra90 said.

Functionally, the 7M system works the same way as the 2JZ-GTE, but the schematic is simpler and the hose routing looks like it would be cleaner.

Me, I'd vent both valve covers to a good air/oil separator, then run the output of that puppy to the intake after the MAF (if you're running one), but preturbo.

Zuffen if you're reading this, do you know if that outfit is still in business that was building the nice air/oil separators a few years ago? Julian did a feature on them in AutoSpeed.

 

[Zuffen]

John,

I'll try and find out for you today.