Rigid_EVO Breather / oil blow by

[thinktank]

Originally Posted by Deimus

If your problem turns out to be the umbrella valves, then since you have already routed your breathing to a hose (probably via a horseshoe pipe) you can solve your problem by installing a high quality one way valve onto your breather hose. You may be tempted to try to fit an automotive style PCV valve since they are low cost but I don't recommend this. Those PCV valves are usually spring and check ball based which will not provide the fast action and sealing you need. I have a Krankvent ETSE valve on my breather hose. These are somewhat pricey, but they are self cleaning and are high quality. Actually, you can't go wrong by adding a high quality one way valve to your breather hose.

If (and only if) it turns out that your significant source of excess air/gasses is from blow-by, then you have the choice of fixing your ring seal issue or you might want to re-think moving your venting from the heads down to the cam cover like I did. With the oil baffle in front of the new breather fitting, this is a less oil rich environment for the venting. If you want maximum performance, then you will need to address your ring seal.

One additional benefit of venting from the cam cover is that you will be able to run a full tank of oil without it causing your rocker covers to leak. Running a low level of oil seems like a poor solution to leaky rocker covers when the best solution is to address the excess pressure inside the rocker boxes which is the actual problem to begin with.

good stuff, i like the simplicity of the krankvent. thanks

[thinktank]

completed the leak down check (not super easy by the way trying to keep the piston at tdc) front cylinder 10-15%, rear cylinder 10%. rechecked compression for grins, 183psig front 193psig rear. pumped air into the each breather to try and figure out if one was leaking more than the other, they both suck...leaked equally as bad. back to the drawing board and will try to get the umbrella's seating better. i if i can't get them to stop allowing air back into the crankcase i'm going the way of the krankvent as i have no more fahks to give with these umbrella valves.

[rejeanprimeau]

I had this issue way back. The solution I've found was to dial my bolts breather's hole up. The pipe is sent up over the umbrella valve level. I'm still usin an horse shoe set up but, by making sure the oil can return in the motor via the vacuum cycle, I've minimal leak from the hose end and the vapor can escape. I don't use anything at the end of the hose who rest near my tranny breather.