Teddy952

Ive been trying to track down what could be causing a slight oil burning smell. It usually occurs while on boost or just after lifting the throttle. The smell is more noticeable in the 12 to 15PSI range and no smell under 10PSI. Looking at the oil pan I noticed that there were some small oil drops on the oil pan right above the exhaust's factory test port. I'm guessing that the burning smell is when the drops land on the hot exhaust.

I figured that I was somehow pressurizing the crankcase seeing as though I smell the burning oil while on boost or just after. I connected a barb fitting to one of the cam tower's ports and ran vacuum hose to a vacuum/pressure gauge located in the cab.

At idle, cruising or under full boost (15 PSI) the vacuum gauge doesn't budge from zero. As soon as I dip the clutch or lift the throttle, while under boost, the vacuum gauge will show a pressure spike in the crankcase. The higher the boost the greater the pressure increase. I noticed that under 15 PSI boost when I change gears the crankcase will spike up to 8 PSI and then back to
zero. In fact whenever my Forge recirculating valve diverts the compressor surge back into the MAF tree is when I see any positive crankcase pressure. As a test I vented the Forge valve to atmosphere and blocked the port on the MAF tree. I did multiple full boost runs and the crankcase didn't pressurize what so ever.


When the diverter valve dumps back into the MAF tree the pressure travels backwards through the catch can and back into the crankcase.

Has anyone else noticed this or am I just special?? :-)

I should say that I'm using an Electromotive ECU so the car runs the same if the diverter vents to atmosphere or not.

Pauerman

Some great info in this thread - crankcase pressure

Teddy952

thread link dead? Doesn't appear to link to another page.

marcoturbo

Since a working DV recirculates air to the intake in the MAF tree, it's no surprise it goes back to the crankcase through the catch can. Maybe a one way valve in the AOS line between the catch can and the MAF tree could help.

Willard Bridgham 3

A failed diaphragm in the blow off valve will cause a pressure spike like this, too.

Teddy952

Ill try a check valve and Ill also check out the Forge DV for any failures.

Seems odd that there would be pressure at all in the turbos inlet when the DV dump into it. There is a cone filter about a foot away from where the DV connects to the MAF pipe.
I looked a little closer at the MAF pipe and the port where the DV dumps into it is directly across from where I have my catch can plumbed in.
Im thinking that when the DV dumps all the pressurized air into the MAF it shoots it directly across the MAF tree and down the catch can's connection??? Maybe?
Looking at Rouge tunings MAF kit you can see that the where the DV connects is angled towards the turbo's compressor wheel.

marcoturbo

The hardest is to find the proper check valve.

I have a Saikou Michi catch can and after a quick search the only 3/4" check valve I've found are designed for boat sumps...