How to close the engine vent tube

[Kevin Erion]

The following pictures that Ray Davis is going to post for me will show an installation we just did yesterday on my bus. I had Walker Engineering build and install an Air-Sep on my motor. This eliminates the engine vent or draft tube that exits under your engine on the driver side by the oil filters. It then closes the crank case, better for air quality! For me the reason was to make sure the area behind the engine stays dry and clean. The other up sides to the Air Sep is it takes your engine from a positive crankcase pressure into a slight negative pressure. This should be worth a little, I said little extra HP and fuel mileage. Just wanted to share this with the group.

[Ray Davis]

Pictures from Kevin ....

[James]

Kevin,

Looks great and appears to be well designed.

Any down side to this?

What's the cost and are they willing to build more?

[HarborBus]

Kevin ditto from me. I'm liking the possible increase HP and and fuel mileage. I just had the Silverleaf 440 installed and am hoping I can improve the mileage some by driving the coach at max efficiency. I'll try to post some pictures.

[LarryB]

Kevin, the second pix that was posted shows a finger print on part of the assembly--tisk-tisk-tisk, Just bustin your chops. If my engine ever looked that good I would take Jon's advice, take off the "plastic sheld" and park the Bus in order to keep it clean.

Good post, keep us up dated on the performance changes.

[Kevin Erion]

I don't think I will see any gain in MPG, and I am somewhat ashamed that I didn't clean off the finger prints before the pictures. I think the gain comes from no loss of oil, no oil on the rear and bottom of the bus and possibly easier on engine gaskets and seals. I can find out what the price would be for this kit and post what I find.
Elliot, please say Hi to Steve and Kate!

[flyu2there]

Kevin,

Couple of questions. Am I looking at a super-sized PCV system where essentially the breather is attached to the intake system in order to burn the breather discharge? If so CARB (California Air Resources Board) will be proud of you! Second, what impact might that have on the turbo as it appears that you are connected up stream of the turbocharger? I am thinking that diesels engines produce far more blow by than gasoline engines, the turbo gets very hot, and coking may be an issue; have no ideas about the intercooler. Looks like there is an oil seperator in the unit, where does that discharge and is it powered by a vacume source?


John

[Jon Wehrenberg]

Kevin,

You have only yourself to blame for the fingerprint remark. All I can say is that it has just started. Until you assumed the position of Anal 1.1 I had to put up with all manner of remarks. Now I can sit back, enjoy my coach without cleaning it as soon as I get anywhere, and I can now take potshots at the person who has assumed the title. (I won't unless I have a huge opportunity, and a fingerprint doesn't come close).

But I digress. I am confused. In looking at your installation it appears you are collecting engine breather discharge (possibly by creating a negative pressure at the separator), and metering that oil laden vapor into the fresh air intake of the turbo. Is that correct?

If so...would not a simple PVC valve have functioned the same?

And if I am understanding it properly I question why this is not required for all our engines especially since it is such a simple issue to address.

[Kevin Erion]

This unit is about 90% efficient in separating the oil from the air and allowing the oil to drain back down to the bottom of the engine. If you see the blue hose at the bottom of the can, that is the drain and the other end is taped into the turbo oil drain fitting on the side of the block just above the oil pan.
I can't explain all the details but this unit is sold in the marine world for the most part, they can not allow any oil to collect in the bottom of the bilge. It uses the air intake as a siphon to evacuate the crankcase pressure out and then thru a filter system which separates the air and oil allowing the oil to return to the engine. It does not restrict the incoming air so no loss in flow there. I installed and older version about 12 years ago on a 1990 truck I owed with about 350,000 miles, it always marked it's parking spot with about a 2 inch circle of oil on the ground from the draft tube. After the install, we put another 350,000 miles and never had a problem, with no service to the unit.
They claim the older unit was only 25% efficient in separating the oil and air so if this one is that much better than the old one, I have nothing to worry about.
As to why the large diesel engine company have not closed the crank cases, one can only assume its because of money.

[Jon Wehrenberg]

These separators are in wide use on general aviation piston powered planes. I was glad to see you are not discharging the collected oil to the intake because of the turbo problems that would have resulted. However, by pulling a vacuum on the breather are you not pulling more vapor than would otherwise be seen on the crankcase breather?

The crankcase gets positive pressure from ring wear, which in turn pushes more and more air (the product of combustion so it is really not air) into the crankcase. That air is dirty and gets dirtier as the engine wears and it increases in volume as the engine wears. It has lots of carbon particulates so in this case that dirty oil is being returned. Personally I would rather just see a gravity trap that would be drained at every oil change cycle.

On planes, which consume a lot of oil, most of it out the breather, trapping that and returning it to the crankcase doesn't make any more sense to me, but it has been an accepted practice so there will be no changing it now.

I doubt if it is a money issue as much as the problem is so insignificant as to be not worth the engineering time. Right now I suspect all engineers working for all engine manufacturers are working hard to put exhaust into the environment that is cleaner than the air in that environment.