Road tube...

[saturntech95]

OK so my engine is almost all back together with a few goodies, all I need now is a good tune. Now heres the deal...

I had my motor road tubed for a while before it blew (failure was not related) but I know alot of people on here argue that it causes excessive crankcase preasure to build. I was thinking that the preasure built up is due to the CDR not having that slight vaccume on it from the turbo pulling. So what do you guys think if it was ran with no CDR just a dump tube? That will let any preasure out of the bottom end no restriction.

Arguments/Oppinions?

 

[BigBlueChevy]

For one thing the CDR is designed with POSITIVE CRANKCASE VENTILATION in miind. It creates a negetive pressure in the crankcase, preventing oil from blowing past the seals. Its also apparently an emmisions device to use Positive crankcase ventilation, though I'm not sure how.

There are a handfull of people on here who have added, not a road draft tube, but the same basic idea. One of them I remember was the "provent crankcase ventillation system"

Personally, I keep away from them. Having negative pressure in the crankcase means less of your precious oil blowing past the seals to the outside. By having crankcase pressure at the same or slightly higher than atmospheric pressure, the oil is going to want to go out.

 

[Veg_Out]

Why not just reconnect it?

 

[Brooklyn Tow]

Whats "Road Tubed"......Vented to atmosphere?

 

[WarWagon]

You get free economy from the oil vapor and less leaks from the engine with the CDR working. Air leaking in through a seal keeps oil from leaking out of the seal vs. at atmospheric both sides of the seal. The hot oil that vaporizes easily from the valve covers isn’t the best place to pull it from. The old 6.2’s used the oil fill with a timing chain baffle. You could look at other posts here about doing that 6.2 CDR mod.

Do you have an intercooler to keep clean? This would be the only reason to go road draft tube. Other than severe blowby club members…

 

[NVW]

Whats "Road Tubed"......Vented to atmosphere?

It's just a tube that is vented to atmosphere, it usually drops to the base of the engine to keep vapors off the it.

 

[Joey D]

I run the road tube. The CDR has a spring in it that sets the pressure and i doubt the intake pulls much if any vacume on it. I don't think it going into the air intake does anything more than try to clean up the vapors by burning it again.
Look at any of the older diesels and they all ran the road tubes until emissions required it to be run back through the engine.

 

[jchase]

i ran one for a while but the problem i found was the little bit of oil vapor gets all over what ever your towing. that's if you tow long distance

 

[BigBlueChevy]

I run the road tube. The CDR has a spring in it that sets the pressure and i doubt the intake pulls much if any vacume on it. I don't think it going into the air intake does anything more than try to clean up the vapors by burning it again.
Look at any of the older diesels and they all ran the road tubes until emissions required it to be run back through the engine.

Exactly. The New Holland (both 6.6L and 7.8L) run road draft tubes. So does the DT466 at the yard. In fact, it doesn't seem that positive crankcase ventilation came around till the 90's.

 

[ak diesel driver]

Check out the rings on those diesels. Thats why ours get blowby but still run fine.

 

[saturntech95]

Exactly. The New Holland (both 6.6L and 7.8L) run road draft tubes. So does the DT466 at the yard. In fact, it doesn't seem that positive crankcase ventilation came around till the 90's.

Those are just a straight tube right, no CDR type setup. It seems to work well for them, I dont have an intercooler... yet... but even now I just dont like the idea of oily vapors in my intake.

I was actually thinking if I run a drivers side valvecover on both sides then vent it like a 6.2 out the middle?

 

[buddy]

The CDRs job is to keep the vaccum to a minimum in the crankcase. It closes the CDR when boost gets over 8psi or so, and that is why you will hear people have their dipstick blow out when they run the truck real hard, because with the CDR closing there is no pressure relief, how that is good idea I dont know, because I can sustain over 10psi for a long time climbing hills. That is why I put the CDR into the oil fill hole and put a breather on the valve cover.

There should be no problem just venting it, other than the oil drips, and it happens to be the highest single emissions output. they started using the PCV so there wouldnt be oil slicks on the road from every vehicle having one, along with cutting the emissions output in half.

 

[saturntech95]

Well my road tube runs down into the center of my frame so the oil will help keep it from rusting. I never knew the CDR shut under boost, good info to know.

 

[buddy]

Under boost is the greatest vacuum. CDR is wide open at idle when there is very little vacuum. As vacuum increases with boost the CDR spring closes.

 

[WarWagon]

Exactly. The New Holland (both 6.6L and 7.8L) run road draft tubes. So does the DT466 at the yard. In fact, it doesn't seem that positive crankcase ventilation came around till the 90's.

The 1988 6.2 I had had a CDR going to the intake manifold.

The Duramax has a big problem with oil from the CDR system leaking out the turbo intake and will drip on the ground. Esp when towing heavy and running hard doing so.

The harder you run it the more oil vapor and blow by you get.

 

[turbovanman]

Cummins had a road draft tube, not sure exactly when they stopped using one but its around the 2000's I think.

Either way, they were done for emission's and to limit the mess they can make, other than that, if you want to run one, knock yourself out, won't cause any issues with excessive wear unless dirt etc somehow gets sucked up, :nono: