CFM Valve Cover Breather

[TomV]

I know the PCV valve allows the crank case to vent under "non-boosted" conditions into the intake manifold.

 

What I don't know is how the crank case is vented under "boosted" conditions. It's not through the PCV because the intake would be pressurized under boost. I've read some manufactures use the turbo inlet piping to pull from the crank case when under boost, instead of the PCV.

 

Not sure how Ford vents the crank case under boost or even at all???

 

Something I did find that would work is the CFM Valve Cover Breather. CFM PERFORMANCE BILLET VALVE COVER BREATHER KIT FOR 2013-2015 FUSION ECOBOOST 2.0

 

 

It contains a check valve that lets pressure OUT,  but nothing IN.

 

I'm curious if anyone has one of these or knows if Ford manages crank pressure under boost?

[02LincLS]

I have read other forums where there were no issues with using it.

Crankcase pressure venting under boost... My understanding, and I could be completely wrong, is that there is a hose coming from the other valve cover (opposite bank than the PCV) with similar fittings, and it goes to the intake side of the turbo (vacuum).

My guess is the vent won't do much unless you unhook this tube at the valve cover. It will probably throw a code if you completely remove it because there is an electrical plug of some kind.

[02LincLS]

I read more on this today and found this...

 

https://www.knowyourparts.com/technical-resources/engine/pcv-system-pressure-managment-in-turbocharged-applictions/

 

" Vacuum is present before the turbocharger. On some engines, the vacuum is greater than the vacuum generated by the pistons moving downward, but not all the time. Vacuum is generated only when the turbo is spinning. Typically, the area before the turbocharger is where the vapors from the crankcase are fed into the engine. Some turbocharged engines will feed crankcase vapors to the intake manifold with a bypass valve when the turbo is not creating enough vacuum. .....  The system directs the vapors to either before the turbo or intake manifold when the time is right. "

 

So it also seems there might be separators built into the valve covers but who knows. It seems like you might need 2 catch cans; one for the regular PCV valve side, and another for the high boost condition side that runs to in between the filter box and the turbo intake. My car is a V6 so there's a tube on each bank. The 2.0 probably has two tubes and both would be on the single valve cover?

 

This hints that all the oil in the intake of my 3.5 EB Flex might not be due to worn turbo seals (thought that's still most likely), but some of it could be from the crankcase vapors being pulled into the intake. If the catch can on the regular PCV side remains dry after a month of use, I may remove it and place it in-line of the tube going to the filter box intake and see what it collects.

 

My last thought is that you'd probably be venting those vapors into the engine bay with a breather. If my conclusion above is correct, a second separator would be the way to go. I don't know if the existing design would work in that location but I might fab up a mount and try it out on the Flex. As long as my MKZ has CPO warranty, I don't want to experiment.

Edited May 17, 2022 by 02LincLS