C6 Z06 oil in the intake issues...

[TLewis4095]

The Dry-sump tank is part of the LS7's crankcase ventalation system as the filtered fresh air for crankcase makeup & flushing comes from the airbridge, runs to the dry-sump tank, then to the plumbing going to each valve cover & the gasses & vapors are vented & drawn through the vally cover (as in all the GenIV designs) where they are pulled into the intake to be burned in the combustion process & exhaust.

The same problem exists today as has since the first LS1 engines hit the road.....a PCV system that allows for some oil mist/vapor to enter the intake & contaminate the intake air charge resulting in a less complete combustion process & the resulting carbon build-up on the valves & pistons robbing power & causing detonation to an extent.

Above are pictures of the bellows & the inside of the intake showing the amount (this Z has 10k miles on it).

Road course guy's already know of the issue since they run at extended periods of high RPM's causing this to be even more evident.

I'm working on a solution w/1Qt oil seperating catch can with integrated PCV check valve & the correct plumbing with additional check valves that will allow the flow to run in one direction only & relocating the filtered fresh air source to a seperate remote breather eliminating this issue.

I'll post pics after I'm finished.

[Tony Skarbic]

Thank you for the information and please keep us informed. Seems the engineers from GM would have solved this by now. Oh, well.

[TLewis4095]

Update!

Below is the oil seperator/catch w/built in PCV check valve can installed:



The stock valve cover lines stay intact:



Using the OEM fitting of the line originally run to the air coupler, the line is removed for this mod & is attached to the new line running forward to the remote breather :



Remote breather mounted in the pass frnt corner of AC condensor. This also has an integrated PCV check vale to prevent back-flow:



So far zero oil in the intake & zero oil mist from the breather. No smelly fumes either.

Have not run it hard to really test it, but so far excellent results.

[pauln64]

if this is a problem, sound like GM needs to do a recall.

[TLewis4095]

Originally Posted by pauln64

if this is a problem, sound like GM needs to do a recall.

GM (and most every auto maker) has had these issues to some extent ever since the EPA emmissions came into play in the 70's, and the stricter they get, the more difficult it is to design an effective system that works w/out oil in the intake & meets emmission standards. To take from what we do for a solution is not practical (and won't meet emmissions) since the oil seperator/catch can must be emptied every oil change & the remote breather will allow some vapors to escape into the air.

Ever since the first LS1 was released it has been a common issue that most are not aware of (just remove your throttle body & wipe a white towel into the intake snout to see). Even though GM has made several improvments in design, such as the LS6 style valley cover, there really has not been a cost effective, maintanance friendly solution that can be worked into their production so it will continue to be an issue.

Here is a rough diagram of the modified system that corrects the issue: