Can someone tell me what this is for?

[nikitis]

Can someone tell me what this is?

It's leaking or spraying a mist out under the bus.

It's on top of the head and has a pipe going down below and is open ended. I do not see any kind of hose that is near it that should be connected to it.

It does appear to be like an exit port for something. Mine is a 1995 3800 3box t444e

[fo4imtippin]

I don't know the t444e, but on this era it's common to have a blow by tube to vent the positive pressure in the crankcase. Some people run a catch can on them, but I ran mine out to the side of the bus to keep the oil vapor outside the engine box.

[nikitis]

So I've heard of catch cans, but never understood their purpose. So is this thing spitting out fuel in a light mist? And a Catch can will catch that, and send it back into the system?

[fo4imtippin]

Originally Posted by nikitis

So I've heard of catch cans, but never understood their purpose. So is this thing spitting out fuel in a light mist? And a Catch can will catch that, and send it back into the system?

Not fuel, but oil vapor. If you take your valve cover cap off while its running, that greasy air is what its evacuating out this tube. Diesels have positive pressure. even if running healthy. Once your engine is shot, youll start to see white smoke come out of the tube. Hopefully a long time from now.

[nikitis]

Where does the vapor come from? Is oil being lost or burned and it’s a by product? Or is moisture from the air finding its way into the fuel burning process and leaving through this pipe?

I’m just curious as to why there is a vapor to begin with.

[fo4imtippin]

https://farmmachinerydigest.com/blow...iesel-engines/

[nikitis]

So sounds like it's the open vent tube. There is only a light mist when first starting which from reading your link the CFM is higher when cold which explains why it goes away after driving and only seen when first cranking it up.

For those reading larger liter diesels have this because some blowby is expected, can cause corrosion if left or too much enters lower oil chamber causing engine bearings etc to corrode faster etc. The tube is there to rid the engine of this combination of Nitrous Oxides, particulate matter and unburned fuel that gets past the pistons.

For those curious why some on here say that driving your buses is better than letting them sit, this is precisely why so it can keep the internals from corroding the blocks and engine internals.

I have No smoke, just a very light mist that you can barely see.

I only noticed it because I was trying to listen for air leaks in my hoses because one of my air lines seems to fill up slower for some reason. It holds pressure just fine while driving. I saw that mist looking for a possible air leak but the 1995 T444E is so damn loud I'll never be able to hear a leak while running. I think to diagnose that I'll need to charge it up to 120 PSI then cut the engine and listen for any leaks.

Thanks for the info. I've been learning a ton about diesels lately. I understand gas engines, and I thought I understood diesel engines but every diesel I come across seems to have their own unique things that aren't on other diesels. I have no such open vent tube on my Mini Excavator Diesel engine, but it's only a 3 cylinder so probably isn't much blowby since it's smaller.

Learning is what it's about here so thanks for the information.

[somewhereinusa]

Just for your info. ALL internal combustion engines have blow by, even new ones. Although when an engine is new not very much. It's a combination of things that get past the piston rings. On more modern engines the PCV system runs it back through the intake and it gets burned and sent out the exhaust so, you don't see it.

[Omnibot2000]

Originally Posted by nikitis

So sounds like it's the open vent tube. There is only a light mist when first starting which from reading your link the CFM is higher when cold which explains why it goes away after driving and only seen when first cranking it up.

For those reading larger liter diesels have this because some blowby is expected, can cause corrosion if left or too much enters lower oil chamber causing engine bearings etc to corrode faster etc. The tube is there to rid the engine of this combination of Nitrous Oxides, particulate matter and unburned fuel that gets past the pistons.

For those curious why some on here say that driving your buses is better than letting them sit, this is precisely why so it can keep the internals from corroding the blocks and engine internals.

I have No smoke, just a very light mist that you can barely see.

I only noticed it because I was trying to listen for air leaks in my hoses because one of my air lines seems to fill up slower for some reason. It holds pressure just fine while driving. I saw that mist looking for a possible air leak but the 1995 T444E is so damn loud I'll never be able to hear a leak while running. I think to diagnose that I'll need to charge it up to 120 PSI then cut the engine and listen for any leaks.

Thanks for the info. I've been learning a ton about diesels lately. I understand gas engines, and I thought I understood diesel engines but every diesel I come across seems to have their own unique things that aren't on other diesels. I have no such open vent tube on my Mini Excavator Diesel engine, but it's only a 3 cylinder so probably isn't much blowby since it's smaller.

Learning is what it's about here so thanks for the information.

Your 3 cylinder has a vent. All engines have a vent. It just depends how it's handled.

While older diesels can vent to atmosphere the new diesels are filtered through a crank case filter and then plumbed into the intake to burn any remaining gases off.

Cars use to vent to atmosphere, now they for the most part is vented through the PCV valve. Also known as positive crankcase vent.

Primary purpose of a the vent is so the crank case does not over pressurise and blow seals out.

I've had a PVC stick(Froze in winter) on my wife's Ford Escape. Blew the front crank seal out 2 weeks after I rebuilt the motor. Thank goodness she realised the car was excessively smoking when she pulled up to the red light. Saved the engine. I will never purchase a SMP product again. OEM PCV was pretty much the same price.

[cadillackid]

they make kits to recycle the CCV gases.. my T444E was fitted with a RACOR CCV-3550 which catches the oil that gets sdent out and puts it back into the pan. the T444E is very sensitive to oil overfill... it will blow oil out the draft tube if you overfill even by a little.. ive kept the CCV-3550 as its nice to not have that tube push out oil at higher RPM

[Omnibot2000]

Plus the smell sucks on the draft tube.

I ran mine up after the thermostat replacement and I could smell it. Might be just me but anything pre emission makes me nauseous now. Probably developing a sensitivity to it. 25 years ago you could cut the air with a knife with trucks running in the shop.

My 97 OBS Ford has more blow by then the bus but I have got it hot once, she is hurt a little when I pulled a 60 x 12 mobile home 8 miles on a side road in 4x4 low.

[nikitis]

Do you guys see any harm in extending the tube via a hose and clamp. I don't particularly like where it's exiting. It's very short and landing on the AT545 keeping it wet.

I was thinking of adding a 1/2in radiator type hose to the end and directing it out towards the side away from the underside of the vehicle.

Seems like a poor design imo.

[somewhereinusa]

Before PCV was a thing and all cars had a draft tube it was quite common to extend them.

[nikitis]

Cool, I see an upgrade in my near future.

[Omnibot2000]

If you do extend it make sure it does not have any sags in the line where condensation can settle. I've seen it freeze up in below freezing and over pressurise the crack case.

[nikitis]

Thanks, and Noted, I'll take care to prevent long horizontal or reverse hanging so there's always a downward point and can drain.

I'll send pics when it's done.

[dalez]

Saw on a cummins forum many people are using a peanut butter jar. Cut a hole in the lid big enough to fit the hose through, and several 1/4" vents around it. slide lid over the hose a bit, wrap a zip tie or two around the hose to hold the lid in place. Tie some steel wool around the hose to act as a filter for the vents, it'll help catch the oil mist which will drip back into the jar. Screw on jar. You just saved $50-200 on a catch can system! Just be sure to check periodically, and drain it before the liquid reaches the bottom of the hose as it can freeze, block the vent system, and pop your oil seals.

[Iceni John]

The peanut butter jar thingy sounds like it would work just fine, even if it's a bit redneck! If you want something fancier, the Walker Airsep does basically the same thing as your Skippy jar: busnuts with 2-stroke Detroits sometimes use Airseps to catch any oil drips coming out of the airbox drains.

John

[nikitis]

I'm honestly fine with just adding a 3/4 fuel hose to it and clamp it and directing it away from my Engine/Transmission.

It's going to corrode them if I don't move this away. I just wanted it pointed more at the ground away from both. I don't really care that it's spitting it out to the atmosphere. My one bus isn't going to cause global warming.

[BriteLeaf]

Originally Posted by fo4imtippin

I don't know the t444e, but on this era it's common to have a blow by tube to vent the positive pressure in the crankcase. Some people run a catch can on them, but I ran mine out to the side of the bus to keep the oil vapor outside the engine box.

I’m thinking that like you said, this is most likely a blow by tube.