PCV/Crankcase breather ideas for someone smarter than me (1 Viewer)

Joined
Aug 12, 2008
Messages
1,014
Location
Camano Island, WA
 
 
My little b3.3 had a crankcase breather that was a hose from the valve cover basically draining to the ground. In an effort to reduce spots on my driveway I added a mishimoto catch can. On my 2 week road trip this filled up and started blowing out the "out" side, which I just left open to air.

So. Im trying to figure out solutions.

1. I got a larger bottom for the catch can and am adding a petcock drain to be able to easily drain in regular intervals. That should help.
2. Debating adding one of these brass breathers on the "out" side of the catch can. Are these too restrictive? Will they clog with oil and prevent the breather from working?
3. Would the ideal solution be routing a hose from the "out" of the catch can to some sort of PCV valve on the intake before the turbo? or will the provide marginal benefit and maximal mess with all the blow by going into the intake and turbo?

my catch can:



Breathers im referencing in #2


 
Last edited:

OSS

Joined
Jun 30, 2017
Messages
2,967
Location
Oblivion
Modern (well 1980's modern) PCV systems use a mechanical PCV valve because the venting is routed directly into the engine intake. The valve controls excessive vacuum loss.
If the crankcase is vented directly to atmosphere, a PCV valve isn't required or desired. It'll just hinder the air flow.

If an atmospheric vent for the crankcase is desired but too much oil blow by occurrs, gravity can help by directing the air stream upwards instead of down to the ground.
A separator would likely still be needed if oil loss is excessive and you wanted things to stay tidy.
It's a project that would take some tinkering to find a good compromise
 

gbogh

SILVER Star
Joined
Oct 5, 2016
Messages
194
Location
Chelan WA
All over-the-road diesels I know of plumb the PCV into the intake. As long as you have a functioning check valve, routing the catch can outlet to pre-turbo intake is probably fine (that's generally what OEMs do). You will have some oil/vapor residue accumulate in your intake and if your intake boots aren't silicone/oil resistant you'll want to check them more frequently. Your catch can already has filter media in it like that sintered brass one you linked.
TLDR- plumb the catch can outlet to your intake (OEMs do it) & check boots & can regularly.
 
Joined
Feb 4, 2006
Messages
809
Location
Raton, New Mexico
 
 
if your intake boots aren't silicone/oil resistant
Silicone rubber is NOT resistant to engine oil or to petroleum products in general. Neither is EPDM, SBR or natural rubber. Fluorosilicone rubber is oil and petrochemical resistant but it is an expensive, specialty type.

Common oil resistant rubber types are NBR (aka nitrile or Buna-N), chloroprene (aka Neoprene) and flouroelastomers such as Viton (expensive).

The best properties of silicone are that it resists degradation by high temp, oxygen, ozone and UV light and that it remains flexible at very low temp.
 
Joined
Aug 12, 2008
Messages
1,014
Location
Camano Island, WA
 
 
Thanks. I think with the deeper oil can I can save some time before oil blows all over the place. That plus the drain petcock will make the whole deal easier. I know the interior of the catch can is baffled and has some media in it. I might try that sintered bolt on the outflow to see if that will stop some oil leakage but allow it to breath. My whole air intake is silicone hose so I don't really want to put a bunch of oil in there.
 

gbogh

SILVER Star
Joined
Oct 5, 2016
Messages
194
Location
Chelan WA
Silicone rubber is NOT resistant to engine oil or to petroleum products in general. Neither is EPDM, SBR or natural rubber. Fluorosilicone rubber is oil and petrochemical resistant but it is an expensive, specialty type.

Common oil resistant rubber types are NBR (aka nitrile or Buna-N), chloroprene (aka Neoprene) and flouroelastomers such as Viton (expensive).

The best properties of silicone are that it resists degradation by high temp, oxygen, ozone and UV light and that it remains flexible at very low temp.
I think I've seen so many silicone products advertised as "oil resistant" in some way that I started taking it for granted LOL. Good looking out
 
Joined
Feb 4, 2006
Messages
809
Location
Raton, New Mexico
 
 
I think I've seen so many silicone products advertised as "oil resistant" in some way that I started taking it for granted LOL. Good looking out
There are standard ASTM test procedures to measure the oil resistance of rubber. But there is industry standard for what qualifies as "oil resistant".

Chances are if you asked the company that made the silicone rubber itself they would not recommend silicone for contact with oil. Ask the company that made the hose with that silicone and you might get a different answer.
 
Last edited:
Joined
Aug 12, 2008
Messages
1,014
Location
Camano Island, WA
 
 
So I added the sintered breather to the output... now just fine oil spray all over! I’m assuming blocking the output will pressurize everything and lead to negative results?
 
Joined
Aug 12, 2008
Messages
1,014
Location
Camano Island, WA
 
 
I put a breather on the catch can output. Didn’t seem to do anything besides vaporize the oil output!

I don’t have a ”true” pcv. It’s just a baffled barb/output from valve cover. I ran a hose from that to an oil catch can... it used to just drain to the ground. But there’s no one way valve in there.
 
Joined
Aug 12, 2008
Messages
1,014
Location
Camano Island, WA
 
 
I was thinking a pcv recirc. Just would have to figure a way to add it and make it look clean... than see if all my silicone hoses would be an issue
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom