crankcase breather question

[billymac61]

I noticed the crankcase breather tube on my m35a2 multifuel is blowing a mist. It wouldbe close to what a burning cigarette smoke would put out.Is this normal or am I experiancing some blowby. Thanks, Bill

 

[JDToumanian]

Yeah, that's blow by. What can you do? Some blow by is normal. My truck has just a little wisp when hot. I certainly wouldn't overhaul your engine unless it started spraying oil. Heck, even then I'd probably just keep adding oil! Extend the breather tube down closer to the road by buying a 3' stick of 1-1/4" hose from NAPA and a hose clamp. Three feet is about the correct length, it will hang in front of and about 6" below the axle between the pumpkin and the spring. This "road draft tube" is supposed to be there unless you're fording water, but most trucks are missing it. It will keep your engine and surrounding areas much cleaner.

One thing to check... Make sure your oil is not diluted with fuel, which will happen if your FDC goes bad. Highly diluted oil will smell like fuel, and will make more fumes from the breather.

Regards,
Jon

 

[WillWagner]

Correct Jon! Remember, that thing under the hood makes lots of heat. The oil has a tendency to get hot too and all those pistons and rods flying around in there make wind. It's gotta go somewhere and it usually takes the vaporized oil out with it. Unless you are loosing quarts of oil after a drive, I wouldn't worry about it. As Jon said though, it is a good signal of what is happeneng inside, steam = coolant/water, lots of white smelly smoke = fuel, so it is a good idea to just take a peek at it after a putt or stick a finger in when you are under it squirting the zerks to see what comes out.

 

[acetomatoco]

A field MWO was to put a piece of oil resistant hose on the breather pipe to get it down into the slipstream further... a foot or more..so you don't get that Diesel Slobber all over the engine... ACE

 

[cranetruck]

The amount of oil lost via the breather is about 1/10 of a quart every 1,000 miles.
I have a filter with a sump and can measure the amount "lost".

 

[OPCOM]

so Will, you say that the trucks pass wind? I believe you are correct!

Has anyone tried extending the 'wind tube' all the way to the rear and letting it vent there? Would there be any advantage? 1/10 of a quart can make a big mess under the truck if it is evenly applied.

I believe Bjorn had made up a canister to catch the oil, and to allow the fumes to be sucked into the air filter housing. This would be the green way to go.. and the captured oil could certainly be burned in the fuel tank.

just some thoughts at random..

 

[cranetruck]

The captured oil can also be returned to the oil pan....

 

[WillWagner]

On occasion, I have heard mine make a kind of PPFFFRRRTTT sound, guess thats the gas passing! I put a piece of hose off of the pipe to just above the diff housing. So far, only a few drops on the axle, but, after a long hard run, there is a bit of vapor. If you choose to run the tube to the rear ofthe truck, make sure there's no dips in the tube or oil will accumulate in the low spots and could cause a restriction in the venting, causing leaks where you don't want them..ie, rear main, front main and any other place that is hard to get at and fix.


Bjorn, check this out. It has been available from Cummins for about 3 years. How long have you had yours installed?

http://www.cumminsfiltration.com/pdfs/product_lit/asia_pacific_brochures/fs_air-enviroguard.pdf

 

[SasquatchSanta]

I ran a 4 ft piece of hose up under the cab, toward the rear to keep the occasional odor out of the cab.

There isn't any visible blow-by with my deuce but I think it is worse when the weather is cold and the heat throughout the block isn't normalized.

I know Rosie runs a lot better and smoother when the engine temp is above 140 degrees.

 

[cranetruck]

....
Bjorn, check this out. It has been available from Cummins for about 3 years. How long have you had yours installed?....

The filters have been used for decades in stationary and marine type applications. My filter is made by Racor and comes in "open" or "recirculation" configs.
I have had mine installed for about 3 years (some 17,000 miles), did it to simplify fording preps along with the permanent compressor-to-air-canister connection, extended air intake and pressurized axle housings. My deuce is almost instantly "fording ready" to 5ft. All I need to do is plug the bell housing and close a valve to pressurize the system.
Several of my MVM articles cover these mod's.

Interestingly, the 8x8 M656 was designed to swim with a minimum of preps and have the breather permanently vented to the exhaust pipe via the pressurization valve, (thingy on top of engine), pressurized axle housings/brake drums, permanent compressor to air intake filter connection and more. Many of these features stay with the other variants, but there is not enough floatation in the rear for the truck/tractor to swim. Like I have said before, the XM757/M656 really exites me, it's the ultimate MV.

Of course, the sealed brake drums and pressurized axle housings eliminates the after fording maintenance required for the deuce and most other vehicles.

 

[clinto]

I firmly believe Bjorn's method is best.

Leaving it in it's original condition inevitably soaks the framerail and top of the front axle with blowby.

Extending with the hose (my current method) is a stopgap-and you can't park it on the driveway for fear of it dripping.

Extending it out the back of the vehicle gives it an opportunity to collect in the hose in a low spot or leave an oily residue on the back or underneath the truck.

 

[billymac61]

Thanks guys for the info. Good idea about extending the hose down Im going to do that, it does tend to make things a mess. thanks again

 

[Pinkie]

BUT if oil is on the frame rails and axle, they will not rust! I have a dribble tube on a DT466 and a 3208 that will mist when hot and pulling, this is normal.

 

[red devils dude]

BUT if oil is on the frame rails and axle, they will not rust! I have a dribble tube on a DT466 and a 3208 that will mist when hot and pulling, this is normal.

he has a point after I got the 5 inch's of goo off my frame rail the original paint looked like
new.

 

[jimk]

Not to down play a worn rings issue ,but this is a part.

One by-product of combustion is water vapor.Just part of blow-by (includes CO2,NOx, SO2, NO2, particulates, H2SO4, various hydrocarbons used ,or perhaps not, benzene...) .

Another water source? The crankcase, being open [to perhaps humid air] breaths with changes in barometric pressure. Water collects inside because the iron is often colder than the surrounding air (from sitting in an unheated environment all night,the coldest part of the day). This may happen over and over if the engine is NOT used, building up a substantial amount of water (it often ends up in the oil). When started the engine gets hot. This water gets vaporized and ejected into a relativley cold environment. The vapor condenses into a white mist much like the clouds above. JimK

p.s. ,and all rings leak ~4-10% std , 2-4% gapless, though good race car builders strive for 0% (during a leak down test~100psi). In the real world it's less, even though the pressure is much higher, because pistons expand and the seal improve and more importantly, the time available for the leakage is much less.

 

[billymac61]

yea I thought about that, I'll be doing away with my automatic undercarrige oiler.