Crankcase Evacuation ideas/thoughts??

[Matt400]

In looking at the Crankcase Ventilation System I began to think its really not all that great and was curious what others think.



I see mine utilizes a vent tube that could be called a draft tube but since it is not in direct air flow and doesn't have and angled slice on the end it surely isn't acting as a draft tube.



So the question is. . would it be better to configure it as a draft tube, leave the rest as is in an attempt to generate a small vacuum on the crankcase

- or -

do that and also add a filtered intake so fresh air flows through the case carrying out the contaminants?



These engines last a long time and seem pretty bullet proof the way they are so maybe I am just over thinking the system but on gas engines its pretty important to expel whats in the crankcase.

What do you guys think??

 

[Vaughn MacKenzie]

Matt, all Ram applications of the Cummins simply have a blowby tube. No fresh air entry, no vacuum scavenging, just simply a port to vent crankcase gasses. Nothing fancy.



The system Cumminst started on the HPCR motor is primarily to prevent oil drippage on the driveway by condensing and returning oil vapor to the crankcase(which amounts to a very small amount of oil).



IMO I think you're trying to put more engineering into this than needed. If I still had my '03 with that valve cover I'd just run a tube from the outlet into a catch bottle and be done with it



Vaughn

 

[Matt400]

IMO I think you're trying to put more engineering into this than needed. If I still had my '03 with that valve cover I'd just run a tube from the outlet into a catch bottle and be done with it

I know, I know and your probably right.



What about the Crankcase contaminants from combustion? are the diesels really that clean you don't need it evacuated?

Seems like a good evac system would do wonders to keep the oil clean.

Older gas engines that used draft tubes required changing the oil all the time and was always jet black just like the diesels.

 

[rbattelle]

Is the breather on the "regular" ISB engines actively evacuating crankcase vapors?



-Ryan

 

[Matt400]

No, I don't see how it could. There is no vacuum like in a PCV system and since there is no fresh air intake for the case you just have a cavity with a vent for excess pressures and nothing to "pull" contaminants out.



Some fancy closed systems like the Marine set up with the Walker Air-Sep devise dumps the vent upstream of the turbo so it (the charger) becomes the vacuum source.

Gotta really have it cleaned up by then or you risk build up on the turbine blades and internal passages in the inter-cooler.

 

[GerryDrake]

Smell

For the smell, I got a plastic "T" that is 5/8" OD on the base, and 5/8" OD and 3/8" OD on the ends of the "T". I pushed the base up into the crankcase vent and ran about a 3 foot long 3/8" fuel hose forward so it picks up air right behind the lower edge of the fan, and ran about a 5 foot 5/8" ID hose rearward from the "T" to get the fumes aft of the cab. I figured this creates a light venturi effect to draw off the fumes, and with the flow through it shouldn't get clogged. Have checked it a few times in the approximate 12K since I put it on and it is clear. The smell that was so prevalent particularly after an oil change is gone. The "T" was a standard issue item in the PCV valve area of the local auto parts store. As I recall it was $10 or $12 for the whole thing.

 

[Matt400]

Hey Gerry,

That was a great mod for the odor, I fixed mine by sealing the cowl area where engine compartment fumes were being pulled in.

I wonder how much "venturi" effect you get on the crankcase?

 

[Vaughn MacKenzie]

Unlike a gasser there is very little contamination from diesel combustion in the crankcase gases, mostly soot which winds up in the oil.



I wouldn't want to circulate much air in the crankcase because you'll really smell the oil vapor stink where the blowby vents to atmosphere.



The contraption on the valve cover doesn't bring air in, only attempts to collect oil from the blowby vapor.



Vaughn

 

[Matt400]

Unlike a gasser there is very little contamination from diesel combustion in the crankcase gases, mostly soot which winds up in the oil.

I think I will just take your initial advise and try the internal baffle first, then add a catch can if needed. Sure would simplify things.