I was looking at Thirsty's engine last night, pondering the infamous PCV "tee". When I bought this truck, all the PCV hoses and the ICV hose were brittle and cracked. I replaced them all, and in place of the plastic tee I made one of brass. I even put a solder plug in the fitting pointed to the manifold and drilled a hole of similar size to the one in the restrictor on the tee.
It all works great. But, I can't for the life of me see the reason to keep the tee in place. I think I get the purpose -- when the throttle is closed, the tee allows a small amount of vacuum to continue to draw crankcase fumes so no evil oil smoke escapes. But, where the main PCV hose connects to the TB, the ICV hose connects directly opposite, so -- there is always going to be a little bit of vacuum on the PCV.
Second, until global warming has us living with daytime temps above 200 degrees, the air inside the valve cover is always going to be warmer than that coming in the intake, so the physics say that that hotter gas will be expanding and therefore will always be headed to the intake, vacuum or no.
Third, the air drawn from the tee, insignificant amount that it is, is still unmetered air. It seems like having all the air running into the engine be metered either through the throttle and MAF or the ICV would lead to more consistent idle, emissions and performance.
And in closing, the restricted hole in the tee is so bloody small, it's probably clogged with gunk from the PCV on most trucks anyway.
OK, everybody get their DWeb on and tell me I'm an idiot.
It all works great. But, I can't for the life of me see the reason to keep the tee in place. I think I get the purpose -- when the throttle is closed, the tee allows a small amount of vacuum to continue to draw crankcase fumes so no evil oil smoke escapes. But, where the main PCV hose connects to the TB, the ICV hose connects directly opposite, so -- there is always going to be a little bit of vacuum on the PCV.
Second, until global warming has us living with daytime temps above 200 degrees, the air inside the valve cover is always going to be warmer than that coming in the intake, so the physics say that that hotter gas will be expanding and therefore will always be headed to the intake, vacuum or no.
Third, the air drawn from the tee, insignificant amount that it is, is still unmetered air. It seems like having all the air running into the engine be metered either through the throttle and MAF or the ICV would lead to more consistent idle, emissions and performance.
And in closing, the restricted hole in the tee is so bloody small, it's probably clogged with gunk from the PCV on most trucks anyway.
OK, everybody get their DWeb on and tell me I'm an idiot.