hisvett

I’m loosing about a half quart of oil per 30 minutes of track time. Most, if not all is winding up in the air intake side of the motor. I pulled the air bridge off today and found oil paddled in the throttle body. I’m running a stock motor but I do run sticky tires so I’m pulling a “G” or so in the corners.

Catch Can? Doesn’t this just catch the oil coming out of the valve covers? Would this keep the oil from winding up in the air breather hose? It looks to me like air flows through the hose from the air breather (air cleaner side of the MAS) and feeds the input side of the air pump located in front of the left front tire, then runs to the air input side of the exhaust manifolds. So how does the oil run upstream to feed oil into the air intake box? What am I missing?

hisvett

After poking around some more, it looks like the oil is pooling after the engine is turned off. What oil is in the line from the valve cover is draining into the T.B. on the manifold side of the butterfly and seeping past into the air bridge.

I have an idea by replacing the oil filler cap with a vent would relieve a lot of pressure in the crank case and keep more oil in the pan.

I did some rummaging around in the shop and came up with enough parts to build an oil catch can. This should at least slow the transfer of oil to the T.B.

ErnieN85

Well for a start what engine do you have?
The LS6 (Z06) engine has a different crankcase vent system just for this problem.
the reason for it is blowby at High rpms there is enough to presureize the crancase and reverse the air flow in the normal pcv system. the LS6 has a oil seperator and removes vapors from the lifter valley instead of the valve covers.
a catch can will help. now if you have the seperator system like the Z06 i'm not sure just what your problem is although a good starting point would be to research the PCV system of the LS1 vs the LS6 Im not sure which the LS2 has

Tintin

This sounds familiar.. When I raced for Nissan, we had a similar problem with the PCV line allowing oil into the intake. The fix was a one way check valve on the PCV line as I recall. You need to get on top of this, we blew 6 engines in a row before we figured this out. The oil pulled into the intake caused the fuel mixture to have an octane rating of about 20 and detonated the engines. In the Nissan , it was caused by high revs in right turns like on to straights.. Then would come high revs in the next gear and boom...

hisvett

Thanks, I'll have to do some checking on where they put the PVC Valve/lines. I did use an air/oil seperator I found in my parts box. I'll be out at TWS this weekend for a DE. Think I'll stay off the revs until I get a handle on it.

BTW, I do have a C5, not the Z06.

Tintin; Thanks for the input.

from Texas

01C5fan

You can put an LS6 valley cover on your LS1 engine. Then adding a catch can will stop the oil injestion. I get around a quarter to a third of a quart per session in the can, but I usually stay off the redline.

davidfarmer

There were some valley covers in the 01-02 range. If you take the intake off then the valley cover, you will see a plastic oil separator glued to the bottom of it. It is supposed to be sealed so that only air can get in, but the sealant fails, and oil seeps in between the plastic and aluminum. Clean it all up, and re-seal with fresh silicone, and let dry thoroughly

hisvett

Thanks for the info David. This sounds very plausible because oil consumption has slowly increased over time. I was hoping to wait until next winter to pull it down for a H/C job. Looks like I’ll be doing it before vacation.

Do I need any gaskets for this R&R or is it all O’Rings and silicone?

davidfarmer

all orings... you don't need anything except the sealant for the repair. The intake bolts are very low torque, so make sure you get my torque list, and an in-lb torque wrench handy.

my torque spec sheet is at http://www.davidfarmerstuff.com/

**that MAY NOT be your problem, but it is certainly a realistic possibility. In my experience, the 01' up cars don't lose a lot of oil unless there is a problem.

Z06 Whisperer

Just a side note on catch cans: My '02 Z06 has one (stock engine) and I get out about an ounce or so of oil per average 30 minute session. I've not actually measured it, but I drain it into a small clear glass container, so I can judge it pretty well.