mark21742

Zeeosix, I think you hit it... I bet he has a non performed hose in there and its a very good possibility that it collapsed on itself

Big Bu Bu

iTrader: (4)

Great thread. Forgive me for popping in here LS6vette. ZeeOsix, I have a bit of a different set up. See pic below. I have a hose direct from the valley cover to the intake. I also have a catch can with a hose from the valve cover to the catch can then out the top of the can to the air intake tube before the throttle body. I noticed with your can you must have an extra port so you can run the valley cover hose through the can first. The best part is your setup uses intake port for both the valve cover and valley cover. See any problem with my setup? Could it allow unmetered air in through the can set up? It is strange.

ZeeOSix

Hard to see all the hoses in your photo, except for the one from the intake tube to the catch can. Based on your description above, it sounds like your catch can is installed on the hose that would normally run between the valve cover and the intake before the throttle body (ie, the fresh air line).

The only reason to put a catch can there is to try and catch any crankcase backwash that would be pushed backward down the fresh air line during WOT use. Typically, catch cans are installed in the line that runs from the valley cover to the vacuum side of the intake manifold.

In your setup, all the air flowing through the PCV system has been accounted for by the mass air flow sensor, so non of it has been "un-metered".

LS6Vette

Here is my 100% stock setup on 2004 LS6

You can see evidence of gas/oil blowing out under pressure where the valley pcv line goes into the intake. The other line is from the pass side valve cover to the tb.

My oil leak is at the pan (lower) gasket & only at HIGH rpm. My theory is the stock pcv orifice or MAYBE the pcv hose line is restricting the expelling of the pressure just enough to cause the leak at the pan. I think GM should have kept the plastic u shape part of the line, but what do I know, they pay their engineers a lot of $$$ to figure that stuff out.

I don't believe it's ever been modified, the guy I bought from did not even put his own air in the tires. Bone stock except for what I have done. Suspension.

LS6Vette

It is oem preformed hose, but after 40k miles & a tight bend, who knows, can I buy just the plastic u shape bit? Probably a silly question, maybe GM will sell it with the whole valley cover for $500.

It has factory markings just like the longer one above it, since I bought it nobody touches the motor but me, or I am looking over their shoulder.

ZeeOSix

Forgot to say that my catch can only has two ports, and it is only installed in series with the line that runs from the valley cover to the intake manifold (high vacuum, backside of the throttle body).

The fresh air tube just runs from the valve cover to the ATM pressure side of the throttle body. In setup, if my engine had lots of blow-by, it's still possible for oil vapors to backwash down the fresh air line and dirty up the front of the throttle plate.

ZeeOSix

I doubt the pre-formed rubber hose is the problem if it's the stock piece.

There seems to be a lot of oil residue around the port where the PCV line connects. I'm wondering of there isn't a good seal there. If air is leaking past the hose where it connects to the intake, then it could be causing less sucking effect on the crankcase. It would also be causing a slight vacuum leak.

Do this little test. After the car is warmed up, pull the dipstick when it's dark and then take a flashlight and shine the beam around the top of the dipstick. Look for crankcase vapors coming out of the dipstick. If you see them, then your engine has lots of blow-by and/or the PCV system isn't working right.

LS6Vette

For sure there is NOT a good seal there, I can slip it on/off with no effort & the leak there speaks for itself. It should have been built with a bulge or a clamp. The rubber of the hose is hard & more oval than round, I imagine from heat and the stress of the tight 180 deg path in such a short distance.

I will do the flashlight test tonight. Thanks.

ZeeOSix

I'd start by get a new OEM hose from the dealer for sure.

odarabla

iTrader: (1)

Well it sounds to me like you already know what's the problem.. Good luck..

Big Bu Bu

iTrader: (4)

Hmm..... maybe the problem is the GM 90MM fly by wire and the Nick Williams 102 fly by wire TBs like I have do not have any vacuum ports at all. The FAST102 intake has one port behind the TB (used for the valley cover hose). I do not have the port on the TB that LS6Vette has pictured in his post or on the top of the picture below. My car has been somewhat bastardized into a LS2 style TB setup which is another subject. Thanks for your help. I picked up some knowledge.

ZeeOSix

The hose that runs from the top of your catch can to the side of the intake tube basically functions the same as it would on the stock GM throttle body. The fresh air hose on the OEM GM throttle body is still on the front side of the butterfly ... it's just located on the body of the TB assembly and still supplies fresh air from the ATM side of the butterfly.

Any port that is before the TB butterfly, and after the mass air flow sensor inside the intake tube will do the same thing ... supply fresh air flow down through the crankcase and back out the valley cover to the vacuum side of the throttle body.

Big Bu Bu

iTrader: (4)

I always questioned that set up. Thanks for the info.

ZeeOSix

Anytime ... like I said earlier, your setup is non-typical where the catch can is installed in the fresh air like instead of the dirty crankcase vapor line of the PCV system.

kenp

iTrader: (9)

I put a one-way pop off valve in the oil filler cap. so long as there is negative pressure in the crankcase the pcv system operates as designed. If there is any positive crankcase pressure the pop off valve will release it.

However, if you had enough crankcase pressure to blow oil past the oil pan gasket, it would seem the oil dipstick would get blown out of the tube first.

ZeeOSix

Did you purchase that or make one up yourself?

My thoughts too. I've heard of the dipstick popping up off the tube from excess crankcase pressure on blown cars.

LS6Vette

The dipstick never moves. I tried the test of pulling the dipstick and looking for fumes with a light & nothing. Engine hot & running idle. Then I took the oil filler cap off & watched that for a while & nothing. Then put my hand over the hole on/off on/off & no change in idle.

It only leaks at high rpm & only at the pan, I am putting a new pan gasket on tomorrow & maybe will vent the driver side valve cover, there is a capped off vent on my 04, unused that would fit a breather & use that for competition only.

THX all & will put a clamp on that U hose.

ZeeOSix

Sounds like a good plan to start with. Let us know how it goes.

kenp

iTrader: (9)

I bought the valve and installed it in an oem filler cap.

I think it cost about $12 delivered.

In my case it was simply a prophylactic measure. I was building a new stroker and wanted to address the potential problem before it became one.

LS6Vette

New gasket is in & I put a little clamp on the pcv hose. I also had to dump the oil (of course) so added more dye & I am going to do a super clean up & monitor for leaks.

I must say for a gasket that is always below the oil line it's not much of a gasket. Little red rubber bead on each side. About a dozen bolts.

It was very interesting to look at the insides of the pan. There is a complete separation between the crank area and the bottom cover of the pan. It's two deparate compartments connected of course to some extent so the oil flows between the two. A two piece oil pan. Should have taken a pic. Sorry. The gasket was a GM part.