DanR

I posted a while ago that my car was using more oil than normal and that there was excessive oil in the intercooler pipes. (I split my intercooled hose recently and had oil spray all over)

I had a leak down test and numbers came in 145, 150, 150 , 145 which good. Thought it may be the turbo however just had it rebuilt and while the cold side blades were a little chewed on the edges and the main thrust bearing was worn nothing to suggest that it was causing the oil issue.

Anyone have any other ideas? I am going to have the bearings done over winter as they are 2 years old since the rebuild and may do the rings as well? (FYI rebuild included new rings, pistons, rods etc etc etc so nothing is that old)

jerome951

Rings and other engine internals shouldn't cause oiling in the intercooler tubes. For that you need to look at the turbo and possibly oil separator. If your rebuild didn't include a new oil separator you may want to have that replaced while your turbo is off, or move to a catch can (on my list of to-dos).

Then again, how much oil in the intercooler do you consider excessive? Mine always has a light coating and a little accumulation at the intercooler outlet and ducting leading to the throttle body.

JohnKoaWood

Did you check the J Pipe (in front of the turbo) for oil as well? Oil in the J Pipe is AOS blowing oil...

No oil in the J Pipe, but oil in the intake tract is caused by the turbo seals.. the seals in the KKK turbos are compression ring style, and WILL blow oil if the bearings are worn... without appearing bad...

any oil pooling in the intake tract is a bad thing... a light coating is acceptable, as you will NEVER get rid of all of it, but if you have any pooling you have a problem that needs to be addressed..

Another fix for the AOS blowing oil, beyond a new AOS, or catch can, is to pack the AOS with COARSE steel wool (like the dish scrubbers) as this will give the oil vapor something to condense onto prior to leaving the AOS... you can also try experimenting with different oils to see if you find one that sprays less in the crankcase, creating less fumes...

Chris White

The rings will cause oil to pool in the intercooler pipes if they are worn. The blow by will pressurize the crankcase and the only outlet is the oil separator – that will be overwhelmed and oil vapor will be dumped back in to the pre turbo intake.

Check to see if there is any oil residue near where the AOS feeds into the intake boot.

jerome951

Makes sense and probably explains the pooling oil in my car.

Oddjob

Leakdown results should be something like 4%, 8%, etc. 145-150 sound like compression results in psi.

Chris can clarify, but I dont think it takes a lot of blowby past the rings (leakdown number do not have to be terrible) to create enough overpressure to blow a lot of oil through the intake on a track/race car. So leakdown and compression may not look that bad, and you may still be getting enough pressure in the crankcase to fill your intake w/ oil.

I have had this problem on two of five 951 motors I have tracked. Both had/have ok leakdown and compression, but fill up the intake with oil.