Help, too much crankcase pressure!
 

Just took the car out on the back farm roads here in NW Texas for a little boost/AFR test. Got the car up to about 10psi and the AFR was down at about 10.5 couldnt really stare at the gauges, was more concerned with going straight!

Anyway, let off in 4th and checked the rear view and could see some smoke out the back end and burn oil smell prevalent....the smoke was actually dissipating after letting off throttle.

On my dyno tune after the motor install the car was having major blowby thru the rear main. I was behind the car on most of the pulls and did not notice any smoke from the tailpipes. Only on the ground under the bell housing. I am running a Monster catch can, it is plumbed correctly and i drilled out the drivers side valve cover port per Traceys recommedation.

I was running the oil cap breather with a check valve on the tune but as you well know we had bigger issues with the P0606 and reduced power mode that took about a month to figure out.

Anyway, i noticed a couple weeks ago that my shop had removed the checkvalve from the breather. This checkvalve allows a little metered airflow into the motor but none to escape. I think my shop removed this check valve to eliminate the crankcase pressure problem.

I know Tracey at Rx says the checkvalve is necessart to not allow un metered air into the motor and could affect the tune. The car drove wonderfully with that open breather BTW.

I ordered a new breather from RX and put it on and just now discovered the car was pretty rich on the AFR gauge at 10.5 and even lower to 10.2 when under boost. Also had the big cloud of burning oil thru the rear main on the exhaust.

So, i put the open breather back on. My tune is a combination of Speed density and Maf.

How does one properly vent these motors so as not to blow seals or God forbid break ringlands???

I thought the Monster Can was the ultimate solution. I am having doubts!

Help

My can is vented. I don't think you will ever find a sealed system that will handle a lot of pressure. I got my can from David Childress aka Mighty Mouse. Same setup he uses on his car.

Well it seems that the check valve removed from the oil cap breather is about the same as a vented can. I just went out and thrashed a little bit and no issues.

Also, when i did have the oil smoke earlier with the checked breather, i notice about 3 puddles of oil under the car. Good news is when the car idles and i remove the checked breather i feel suction on my hand and not puffing smoke like on my LS3 with the blown #5 ringland.

With the open breather it runs a little leaner.....10.7 vs 10.2 with the checked breather. ON the dyno tune with PatG the afr from the dyno showed a solid 11.6. So i think my Autometer Cobalt AFR gauge may be a little off?

Car runs like a scalded ass ape! 10psi from the little D1 is pretty impressive BTW

I've found PCV/catch can setups never worked long on my blown cars. On my Vette and cars before we just ran -8/-10 lines from each valve cover to a catch can with breather. Stopped the cars from building pressure in the crank case which in turns blows out seals.

That was exactly my symptoms with cracked ring lands.

Good luck ... Hope that's not your problem!

Agree 100%

Bull, my car was blowing rear mains bc of two much cc pressure. That was with dual catch cans. It wasn't until we added the oil cap breather that it stopped doing that. You will get some oil smell so when I'm on the street I put the stock cap on.

Keep your car out of big boost and you should be ok.


Gd luck.

Hey Bull.. We had chatted about this a few weeks ago :)

Pull that PCV valve out of the breather. I have run an open breather, with a PCV valve on the intake to valley cover with a small catch can for YEARS back at TTP/ECS. ECS includes this in their base kit, which I personally have seen 16psi out of my 9-second combination.

Cans just don't work under big boost quite well (No matter what brand). I had a problem just recently also blew both valve cover gaskets (I've never seen a LSx in 14 years blow both valve cover gaskets at same time; heck I've only replaced a handful of leaking cover gaskets), I threw on the "ECS" way (Intake Manifold to Valley Cover with PCV valve preventing boost to crankcase, with small air/oil separator with the ECS breather cap), and I'm working perfectly fine now. My plans are to use an open Moroso breather tank (Filtered tank) in the bumper area with both valve covers going to it.

You're lucky that it didn't compromise the seals. We had one on the dyno the other day (C5 vette, 9psi) pushed the rear main, the customer then removed the can and vented to atmosphere (Pretty much how I described earlier), and luckily the rear main seal held together.

Bull I also had the same problem, with that breather the check valve allows air in but not out. I pulled the PCV valve out of the breather. I have been running an open breather with no issues or oil leaks. Good luck

At your power I expect your using a speed density tune so the checkvalve is not needed with SD. Take a plyers and twist and pull it out and let it breathe.

Now, center of can has no valve inline and should connect to the rear of the drivers side valve cover with the fixed orfice drilled out. (we have these on 1200 RWHP builds with zero issues, so we have to figure out what is going on in the system).

One outer connection from can WITH checkvalve flowing away from the can (we had an employee here for 3 months that sent out a hand full with the valve in backwards...make sure it flows away from the can) to the vacuum port on the passenger side of the intake manifold snout.

Second outer fitting with check valve flowing AWAY from the can to the inlet of the head unit as close to the turbine as possible w/out making contact.

At idle, pull line off from rear of drivers side valve cover and make sure you have good strong vacuum at the hose end. If so, slide back on.

Also, are you using stock valve covers? Most after market ones have NO baffel under them and the rocker arms will throw oil right out the outlet fitting and suck in filling the can. Make sure you have a good baffel in the valve cover to prevent this.

We had 2 others with the same issue in the past week. One had the check valve line on the center so it could not evac and built up pressure and had same symptom. Other had the valve flow the wrong direction with the same results.


:thumbsup:

Im just gonna run the oil cap breather with out the check valve. I works fiine. Installed it last night and ran it up to about 7-8 psi and no leaks like when the checked breather was installed.

I would copy what the COPO with a 4.0L Whipple uses. Benefit from factory research, that works.

It looks like they just run a big hose from each valve cover to a vented puke tank. Typical drag racing set up. No sealed pcv, no check valves... that stuff will blow your seals out in a high boost motor.

http://i422.photobucket.com/albums/p...ps022bb5ee.jpg

When I added the breather Ted needed to dial in my tune.

At how many lbs of boost does this start to become a concern?