Crankcase ventilation and vapor control

[veggie]

Could you guys who have built a crankcase vapor control system for your roid please explain the method you used.
After running the engine indoors for a few hours the vapors do fill a room.
Is it best to remove the existing breather and run a pipe outside ? or Route a line to the intake.?
Is a check valve needed in the line ?
I'm sure you guys have already solve questions like this in the development of you system.

cheers,
veggie

[BruceM]

I use the method of the modified brass (water) checkvalve, with pipe leading outdoors. 

I wish I could remember who invented it and posted about it on LEF!  Whoever it was, thanks!

[veggie]

I use the method of the modified brass (water) checkvalve, with pipe leading outdoors. 

I wish I could remember who invented it and posted about it on LEF!  Whoever it was, thanks!

BruceM,
Could you elaborate on that system a bit.
If I had to guess, I would envision a brass flapper type check valve which allows the crankcase pressure to blow outside on the piston down stroke, but blocks any reverse flow on the upstroke.
Where does the fresh air enter your engine on the piston upstroke ? (Crankcase vacuum).

veggie

[BruceM]

I use a  spring loaded brass check valve (valve like an engine valve), with the stainless steel spring cut down to have very little force.  It's mounted on a pipe riser, the stock breather unit removed, replaced by a Taco flange adapter that's a perfect fit.  I didn't invent any of this, and info on it should still be on LEF.

There is no direct air intake to a crankcase run at vacuum.

[billswan]

guys

I went back to LEF and searched for crankcase ventilation and i believe this is the post we are looking for.

http://listerengine.com/smf/index.php?topic=54.15  read down to reply 16

Think i will try this on my 10/1.

thanks for the hint brucem, usually searches on LEF don,t work that great for me, but this time was a jackpot!!!!

[BruceM]

Ah, that brought back memories, Bill, thanks.

Those GM engines sure were marvels- I remembered that they never had any sand, perfect idler gear clearances, no defective parts, great governors, but I had forgotten they also had no smoke from the crankcase, either. 

Sarcasm aside, it makes me appreciate this forum and our courteous vendors, like John, who is so helpful but never gives us marketing BS.

BruceM

[sailawayrb]

If the rings are sealing properly and you haven't over filled with oil, there really shouldn't be any smoke/vapors.  If properly cleaned and oiled, the stock check valve works very well at creating a vacuum in crank case which minimizes oil leaks around the crankshaft seals, etc. whenever the engine is running. 

There really isn't any intended air intake into the crankcase. When the piston is travelling downward, it creates an initial positive pressure that is vented out the check valve.  When the piston travels upward, it creates a vacuum because the check valve prevents any air from entering the crankcase.   

If you run your engine inside your house like I do, it would be prudent to vent the check valve outside to ensure that if there is any exhaust gasses that blow by the rings, you won't get CO in your house.  I accomplished this with a section of flex plastic pipe, the kind normally used for water drainage systems.  It is routed thru an exterior wall via standard dryer outlet.  If you run your engine inside your house like I do, it would also be prudent to have CO detection and a emergency shutdown system.

http://listerenginegallery.com/main.php?g2_itemId=351

Bob B.

[Ronmar]

I do something similar to what Bruce described.  The stock flapper valve plate on my 6/1 was painted shut, and didn't really offer the ability to neatly vent the blowby gasses outside or back into the intake.  The stock flapper valve base plate assembly is held on to the elbow on the case door with 3 screws.  I removed this base plate and cut a round plate the same diameter.  Into this plate I drilled 3 holes to match the original plate mounting holes.  In the middle of this plate I drilled a large hole and welded a NPT pipe nipple.  To this nipple I screwed on a inline plunger type check valve with the spring removed(gravity closes it just fine).  This gives me a NPT port on top of the valve to attach to whatever pipe/hose scheme I choose to vent the blowby gasses...

Here is a pic:
   

How does the air get into the case?  Past the crank seals, past the tappets, past the cover plate gaskets ect.  All the places that would be leaking oil and blowby gasses if the case wasn't put under vacume every piston upstroke:)

[BruceM]

I think Ronmar has the right idea- put the check valve upright, and just remove the spring.  With a brass valve, it has plenty of weight to close, and it will get enough oil vapor to stay free. 

My engine is not so perfect as to have zero crankcase vapors.  I don't get much, but the engine room smelled a lot better after venting it outside and giving up on the old sock method.

[Ronmar]

My engine is not so perfect as to have zero crankcase vapors.  I don't get much, but the engine room smelled a lot better after venting it outside and giving up on the old sock method.

No engine is.  The oil dosn't turn black by itself...

[mobile_bob]

all diesels have blowby, its just a fact of life
how much blowby is acceptable and how you manage it are the only concerns one has to deal with.

the large engine's such as used on hd trucks and other equipment have massive amounts of blowby relatively speaking
and get worse with load, and get much worse over time as things start to wear out.

knowing the baseline and then tracking over time might be of use in determining the condition of the engine, but
because of the check valve system i am not sure how one would accurately measure the crankcase pressure
unless the test was done without the valve?

this forum has raised so many questions, theory, solutions etc in the 4 months of its existence, i suppose it is a testament
to the quality of its members.

very high signal to noise ratio in my opinion

bob g

[mbryner]

mobile_bob:

not sure how one would accurately measure the crankcase pressure
unless the test was done without the valve?

Couldn't you easily measure the vacuum through the oil drain plug hole at the bottom of the sump.  I put a clear plastic tube on it as a sight glass, but the vacuum is high enough to suck the oil right out of the tubing even if it makes a U-bend lower than the engine, so I had to cork the end.  (essentially a primitive manometer)   It's actually tee'd to a ball valve so I can change the oil easier without making mess.

Marcus

[mobile_bob]

Marcus:

i suppose you could do so, however
most if not all the engine's prior to tier 3 or 4 vented to the atmosphere without any form of check valve
so the oem made a test unit that basically was an orifice tube that fit the crankcase vent pipe, you attached
the orifice tube, and to it either a manometer or one of those magnahelix gages and measured the crankcase pressure
under rated load and rpm, then compared that to a spec sheet that was factored for elevation iirc

they published a max limit, which told you the relative condition of the engine, (ring wear)

i would think that any method of measurement used early on in your engine's life would give you a baseline
and a relative idea of what was going on, one would expect a gradual over time increase in crankcase pressure
but, if you saw a marked increase in a short amount of time, under similar load conditions it might be an early warning of
something going awry.

if i were to be wanting to burn alternate fuels such as straight veggie, or waste veggie i would for sure have something like this in place

as you stated a simple utube manometer is easy enough to make up, a broken tape from a measure makes for a nice graduation scale
as does a piece of 1" channel iron for the tape to press down into (it will hold itself by friction/spring force) , with a bit of the wifes red
nail polish one could mark a spot where the engine normally runs under load and then at a glance tell if something is going wrong long before
damage takes place.

with the check valve in place i am not sure how it would work other than to install a orifice in the output pipe/hose and attach the utube manometer to each side of the orifice, that would  indicate in relative terms the amount of blowby being forced out of the crankcase.

having said that an expansion tank is going to be necessary to dampen the pulses, perhaps an old freon tank would do the trick place
between the crankcase and the orifice tube?  thats how the boys at MIT do it.

see attached sketch

good enough for them, is sure nuf good enough for me!



bob g

[billswan]

Mobil bob

On a side note I used a device just as you described to test the condition of a used farm tractor that had a c-8.3 liter cummins engine. At full load on my tractor dyno that engine fell within specs according to cummins, but even though the rings were still good enough to control blow by the oil rings could not control the oil consumption as it would use about a gallon of oil a day 

Billswan

[mobile_bob]

Bill:

you raise a good point, the test is only good at testing one aspect of engine condition
things like bottom end brgs and oil control rings, cam and lifter condition will not show up in this sort of test.

however i think it worthwhile to monitor crankcase pressure as part of any tracking method for an engine
most especially if it is using appreciable amounts of veggie oils for fuel.

bob g