hose running down from turbo resting against front axle?

[treeguy]

I'm on both sides of the fence on keeping the fuel kill out while the truck is off. I thought it was a good idea except for the linkage spring being under constant pressure. But somewhere I heard that keeping it pulled out could harm something in the fuel pump (not sure what, this just sticks in the back of my mind)

If routed to the exhaust is it necessary to have the "SCAVANGING" valve? Is the exhaust pressure going to be so great to overcome the exiting air pressure and force or halt the slobber gasses? Just thinking. The crank case gas pressure probably increases in ratio to the increased exhaust pressure at increased rpms.

 

[Flyingvan911]

I'm just going to leave mine like it is. It's sort of the deuce version of taking a leak.

 

[ODdave]

I'm on both sides of the fence on keeping the fuel kill out while the truck is off. I thought it was a good idea except for the linkage spring being under constant pressure. But somewhere I heard that keeping it pulled out could harm something in the fuel pump (not sure what, this just sticks in the back of my mind)

If routed to the exhaust is it necessary to have the "SCAVANGING" valve? Is the exhaust pressure going to be so great to overcome the exiting air pressure and force or halt the slobber gasses? Just thinking. The crank case gas pressure probably increases in ratio to the increased exhaust pressure at increased rpms.

If that port in the exahust is placed correctly there will be a vacum created, this actualy draws the vapors out of the cranckcase in an atempt to put it in a negative pressure. The valve is there to help maintain this vacum and to help from a fire spreading.

 

[treeguy]

Any insite to where "placed correctly" exactly would be? I'm thinking that a significant hole will have to be drilled and a tube welded in so the rubber flex hose can be clamped to it. Of course some how installing the "SCAVANGING" valve in line, right? All this work, I think I'd keep mine stock and sacrifice the scuba diving.

 

[ODdave]

Any insite to where "placed correctly" exactly would be? I'm thinking that a significant hole will have to be drilled and a tube welded in so the rubber flex hose can be clamped to it. Of course some how installing the "SCAVANGING" valve in line, right? All this work, I think I'd keep mine stock and sacrifice the scuba diving.

To be totaly honest, I am not %100 shure in this application. I would think on the outbound portion of the J-pipe, in the wheel well might be best but I am not shure. On our V8 chevy's they are in the headder colectors.

 

[a-donof2]

Its called a down draft tube.

And at one time the epa said it was okay to do this. Now today that is not legal so they now have to but a the breather on the intake side before the turbo. On modern day diesels I have never had a dirty compressor wheel in the turbo, but you will get puddles of oil in the tubes and manifold.

 

[cranetruck]

it would be neat to have some sort of PCV system on the truck though so it didnt smoke on the ground like it does. i think cranetrucks LDS 465-2 has his breather running in his exhaust pipe after the turbo (maybe to simplify fording?)....

Yes, it was done to simplify preparations for fording, swimming in particular. The m656 series with the LDS465-2 engine has an engine compartment that can be completely submerged with a 5-minute "pressurization of components" wait only.

I added a crankcase breather filter (Crankvent) to speed up fording preps on my deuce. The filter picks up the oil in the vent fumes and can be returned to the crankcase or otherwise disposed of. The fumes go back into the air intake mostly, the tube ends an inch or so below the mushroom. Had it this way for years and no problems.

Nothing is wrong with the original, but these "toys" are like erector sets and it's so much fun to experiment.

 

[randini]

Its called a down draft tube.

Or a "Road draft tube". All older vehicles have this.
As it is now, it is just excess pressure that is vented to the environment. As the pistons move in the bores, the volume in the block changes. The road draft tube creates a solution to this. It also work to help if there is a lot of "blow-by" from bad rings.
To route this into the Vacume of the intake is not always an improvement. If routedto an intake, there now is significant suction, one must create and filter this incoming air. One would not want to be sucking unfiltered air through the engine and into the intake. The only improvment with the removal of the road draft tube is that, any crancase fumes are burned in the combustion chamber. I can see no other improvment. Just my 2c
Thanks

 

[big hoss]

So can I cut it and make it shorter and have no problem? Or should I rerout it into the intake?

 

[randini]

So can I cut it and make it shorter and have no problem? Or should I rerout it into the intake?

It is designed to be down in the flow of air. If you shorten the tube, it would change the function. The air rushing by does create a draft (suction).
Thanks

 

[Heavysteven]

Mine came out of service with out one. I found mostly it helps keep the engine compartment dry. Any excess oil and smoke hits the ground.

It's the blue hose in the middle if any did not know.

 

[Brad Nitzke]

just my but, its a breather, air has to go both way. cuz when the piston gos up it would creat a neg pressure and air would have
to enter the crankcase, correct? just my understanding of what my shop teacher told us. but dont make fun of me im just 16 and still learning!!!!

 

[Akicita]

My slobber tube reaches just below the axle. None of the discharge collects on the axle. The lower end of the tube is cut at an angle to maximize air flow. Sorry, I don't have a picture.

Upon close examination, we found the tube was rubbing against a brake line. We fixed that with a piece of garden hose and a cable tie.

 

[cranetruck]

It is designed to be down in the flow of air. If you shorten the tube, it would change the function. The air rushing by does create a draft (suction).
Thanks

If you measure the pressure in the crankcase, you'll find it's slightly positive. There is no under pressure and the original "road draft" tube just helps in getting rid of the oil laden fumes.
The filter in my application does not create a restriction. It is a common solution to engine installed "indoors", emergency generator systems etc.

 

[doghead]

So can I cut it and make it shorter and have no problem? Or should I rerout it into the intake?

As it is now, you could drive into water up to your air intake, how much deeper do you need to get? You do know of all the maintenance required after driving in deep water or mud, right? These things are trucks, not submarines.

Why would you want to cut it shorter?

What is wrong with it in stock form?

 

[kastein]

These things are trucks, not submarines.

something that a lot of people do not understand

 

[cranetruck]

Mine came out of service with out one. I found mostly it helps keep the engine compartment dry. Any excess oil and smoke hits the ground.

It's the blue hose in the middle if any did not know.

There is a PS mag note on this mod, no biggie, just keeps the starter clean...

 

[cranetruck]

As it is now, you could drive into water up to your air intake, how much deeper do you need to get? You do know of all the maintenance required after driving in deep water or mud, right? These things are trucks, not submarines.

Why would you want to cut it shorter?

What is wrong with it in stock form?

Depends on what "As it is now" refers to, the crankcase will take in water if the breather tube is not modified from stock when the water reaches the air intake.

If the "What's wrong with it in stock form" question is directed to me (you asked twice), there are two reasons, one to simplify the fording preps and the second is to reduce air pollution.
Have you presented that question to all the deuce bobbers/butchers on this site?

 

[doghead]

It was not directed to you Bjorn.

The OP asked what it was, then asked how deep he could go with it as is.

All the others seem to tell him it needs to be modified.

I can understand modifying with a purpose in mind(as you did Bjorn), but that does not seem to be what he asked, or what he needs.

It is interesting to see how others modify their trucks as they see needed. I was simply asking a (related) question and nobody seemed to answer it.



Also, as is usual, the basic answers to his questions are easily found in the Tech Manuals. Nobody seemed to offer that advice. As a new truck owner, I think the single best thing he could do for himself would be to acquire and learn how to use the manuals.

Here's a taste of what they contain...

 

[cranetruck]

...

No problem Eric, theoretically, since there is some positive crankcase pressure and the tube originates on top of the engine, the engine must be submerged for water to enter.

The TM's are generally not good at explaining the "why", the only state what must be done and how to use the equipment. The exception being TM 9-8000, perhaps.

I don't mind this kind of question, it's what makes the forum, IMHO. Even if obvious, I would not refer to a TM, I learn something from trying to answer each question, even if I have to look it up, it's all part of the fun of helping.

PS. Had to include the quote to be able to post.