quite possibly the best modification I've made yet!!

[Forrest Nearing]

I routed my road draft tube to my downpipe!



I bought my truck w/ 208k on it...



I freaked out the first time I took it for a road trip and it coated the underside and backside of the truck w/ oil mist...



it wasn't so bad if I went to the coin-op and hosed it off every now and then... but lately I've been neglecting it, and another 35k miles of hard driving means a little more blowby I'm sure... and all that oil vapor collects and coats everything, and I end up with drips here and there, and it's just annoying...



finally got fed up w/ it, and went and got some good 3/4" hose at the hose/fastener shop. looks like the hose you see on fuel pumps at the station.



routed it down across the bellhousing and bent a piece of 3/4" round tube, blew a hole in the downpipe, stuck the tube in the pipe at a 45* angle, 45'd the end of the tube inside the downpipe and connected everything up.



used almost a full bottle of Simple Green cleaning up underneath the truck (STILL a fair amount of grease here and there! LOL!)



I've put a couple hundred miles on it at 70-80mph...



ZERO drips under the truck (even driving around town, the road draft tube would put down a drop or two often times)



ZERO oil residue on the tailgate.



obviously it would be ideal to have a motor that didn't have this much blowby, but it's still within cummins spec, and I would imagine that even tight engines would benefit from a pan evac setup... creating a vacuum in the crank case frees up power and promotes better ring seal.



wish i'd done this the day I got it!



Forrest

 

[Matt400]

I would think after a while you will be seeing smoke from the tail pipe as oil residue collects and reacts with the EGT's.

 

[Forrest Nearing]

no problem, I won't be able to differentiate it from the smoke that pours out of it all the time anyhow



Forrest

 

[ToolManTimTaylor]

Whatever anybody does don't do it with a REMOTE exhaust brake!!



I allways thought of doing this exact thing. Mine drafts @ the center skid plate and the exhaust brake is juuuust about there. I will of course tap in POST brake but I have more important things on my list :-laf but this one may make it up to the top sooner than later.

 

[moparguy]

Forrest, I guess you've disproved my main concern with a vac setup. That being, that with a boosted engine/pressurized block, you could pull oil out the draft tube, leading to massive oil depletion.



Guess my fears were groundless. Thanks for the report.



RJR

 

[Swayse]

knew you'd love it.

 

[Forrest Nearing]

knew you'd love it.

it's SO strange to not have oil film all over everything... thanks for your help!



Forrest

 

[Todd T]

Forrest, I guess you've disproved my main concern with a vac setup. That being, that with a boosted engine/pressurized block, you could pull oil out the draft tube, leading to massive oil depletion.



Guess my fears were groundless. Thanks for the report.



RJR

since the oil level is nearly a foot and a half lower than the vent tube, one would have to draw one hell of a vacuum on that thing

 

[Huff N Puff]

Unless you actually measured the pressure in the draft tube under all driving conditions you wont know if you are drawing a vacuum or pressureizing your crankcase with exhaust soot.

 

[TJany]

vacuum or pressure?

i don't know about your setup forrest, i would think that you would actually pressurize your crankcase, which is a bad idea in itself. a crankcase under vacuum is definitely better as it gets any explosive gasses out that could possibly be ignited by a hot bearing or other source of ignition, it happens regularly in the maritime industry. if the crankcase is actually pressurized your looking to soot up your oil, as well as pump un burnt fuel into your oil supply, neither of which are good. if it were me i'd put a gauge on it and figure out which way it is

Tim

 

[barrfishe1]

You could try hooking up a vacuum/pressure gauge to the dipstick tube and compare readings with and without the road draft tube connected to the downpipe

 

[lmills]

whether it produces a vacuum or creates a pressure situation has to do with how the pipe is installed in the down pipe. The set-up he used in an old racers trick which helps helps seal pison trings by means of crankcase evacuation. The exhaust crossing by the angled tip causes a draw which pulls the pressure out of the motor. The worst case would be that it would draw more oil out of the tube

 

[CFowler]

look at the bright side of things, the area oiled up probally wont rust.

 

[towner]

put a check valve in the ststem and you'll be where you want to be.....

 

[mjoppie]

i agree that it is sucking on the tube, its just like a innertube, take a blow chuck and blow on the valve stem of a empty tube and it will suck every bit of air out of it, same principal. i wish i would have done sompthing like that years ago on my 98 i will be doing that on my 95 soon.



matt