Oddjob

Even with a fresh motor (good leakdown) and a factory fresh turbo (same symptoms with previous turbo) and having tested a breather/catch can (which did not collect any measureable amount), I still get a lot of oil blowing through the intake/vacuum system.

The little plastic diaphram valve, part of the charcoal canister system, sitting in front of the firewall on the driver side, fills with oil (you can see the oil level inside the white/tan face of the valve). My cycling valve fills with oil and will fail open - I have to pull it and drain oil out of it every other event so it wont plug open. I have a lindsey club gate and I have drained oil out of the diaphram housing on that too.

There should not be enough air flow down to the WG or over to the charcoal canister valve for oil to blow through - should just be pressurizing the lines. I have not had problems like this on other 944Ts that I have tracked. Anyone else see oil like this in dedicated track cars, or know if there is a fix?

Thanks,

carreracoupe997

Jim, assuming the oil is not from the turbo or blow-by, is it possible that the master cylinder has leaked inside the brake booster? Remember, at idle or when you are off boost, such as decelerating through a corner, the engine is pulling vacuum so no pressure is going through your vacuum lines. Just the opposite,they are sucking. If brake fluid has leaked inside the booster it would be sucked back through your system. This is just a wild guess.

adrian1

Does it smoke due to this?

carreracoupe997

Oh, just thought of this. Maybe your intercooler has oil in it. Take it out and degrease it on the inside. I use me jacuzzi and dawn dish washing liquid. I just shoot the water from the jets through it wile its submerged. Works great and really pisses my wife off. I suggest doing it when she is not around.

Oddjob

What Im finding is engine oil.

Nothing other than the typical puff when lifting off to shift at full throttle/high rpm. No excessive oil consumption.

There is some oil that collects in the intercooler over time - I have cleaned the intercooler a couple times over the past several years. Im not so much concerned about the oil pushing past the turbo seals and coating the intercooler and runners, but I think its unusual for the oil to go thru the boost control system down to the waste gate, and to be pushed over to the charcoal canister vacuum valves (?).

vette951s

Jim- I also have excessive oil in my intake track, albeit not to the extent you mention. First, a couple questions. What turbo are you running and who rebuilt it? Are you using factory intake system pick up points for your boost signal and carbon can purge valve? Do you have your catch can vented to atmosphere?

John

Oddjob

Car has had similar issues with this for several years. During this time it had the original K26/6, then had it rebuilt thru Lindsey racing; then upgraded the car to a used k26/8 and later replaced with a factory new k26/8 unit. Some variation in oil consumption and quantity found in the intake depending on engine condition and turbo condition, but have always been getting the oil in the charcoal canister valve and have now been noticing that its causing problems with the cycling valve and draining down into the waste gate diaphram. Everything is the basic factory setup.

I never got oil in the extremeties of the intake/vacuum system on the two other 951s that I tracked. So I am questioning that something is causing either excessive oil blowing through the intake (although I dont have a lot of oil loss and it doesnt smoke a lot), or something is allowing more than normal airflow (carrying oil mist) out to these parts of the system.

When I had the catch can on the breather vent, I routed back to the intake boot as the original factory vent line. It didnt accumulate anything other than moisture after a day of track running, so I removed it.

Pic shows oil level in charcoal canister valve (looks like a shadow but its oil). It will fill up to the level of the hose/nipple connection - then I usually get around to draining and cleaning it out. Anyone else see this type of oil collection?

carreracoupe997

Your catch can should have ONE line, about 1/2 inch ID running only to the oil/air separator. Your can should have a little air filter on top as a vent. Nothing else other than the one line is hooked to the catch can.

Oddjob

This thread was not intended to discuss routing a catch can - that topic has been beat to death, to no apparent consensus, on many previous threads.

carreracoupe997

Jim, your quote " When I had the catch can on the breather vent, I routed back to the intake boot as the original factory vent line. It didnt accumulate anything other than moisture after a day of track running, so I removed it." I simply meant the catch can does not route to the "boot". The only boot I know is the J boot and that would have sucked the oil right out of the can. Now that the can is gone are you saying you have a hose running from the air/oil separator to the intake? If not how are you venting the engine?

adrian1

Well, what I think is trying to accomplish is similiar to the stock vacuum in the crankcase. However the Catch can should be able to create a vacuum but not suck oil into the j-boot.

JET951

Hi Jim,
ive never seem this amount of oil in the system like you describe. i could only suggest putting your catch can back on the car for your next event and monitor if you have more then normal amounts of oil in it afterwards. that way you can determain if the oil is entering the vacumn system via blowby.
Sean

carreracoupe997

Adrain, The catch can does not need a vacuum. The pressure within the crankcase is enough. Only a breather on the can is needed to vent the pressure.
That is the whole idea, not to vent the engine crankcase back through the intake. They did this from the factory for emissions but we are talking about a track car here.
Jim, look at Lindsey Racings vacuum hose routing diagrams and you will see it is only possible for oil to enter the vacuum lines from the intake. Ok, how does oil get in the intake, turbo seal or venting from the air/oil separator. Look at your vac hose routing from the wastegate, which you said had oil in it. From the wastegate it goes to the cycle valve. The other 2 lines from the cycle valve go to the compressor side hardpipe before the intercooler. The other line goes to the hardpipe going in the intake, The oil can ONLY enter your cycle valve from only those last 2 locations. Now how does the oil get in those 2 places?

adrian1

Leaving the vacuum in the crankcase is not only for emissions but better for conserving the life of your turbo seals as well. You will push less oil through the seals if it is old with the vacuum connected too. I'm thinking the two possible problems that carreracoupe997 are correct. Plug that Vacuum and try running with just the went and catchcan and see if it is still doing it.

It sounds like a bad Turbo though.

carreracoupe997

BTW, venting the crankcase(air/oil separator) back through the intake lowers the octane of the fuel once that oil misted air is mixed with gasoline. Maybe ok for the street but not OK when you are running WOT and high RPM's on a track.