Who would like to shed light on this fairly common term but a pain in the butt to find in the search?
From what I could gather its not a big issue, but not a bad idea to vent the crankcase.

 

Blowby is the combustion gases that escape the cylinder by one of two ways. 1.Around piston rings and 2.Around valve seals. This increases crankcase pressure and must be vented, hence the breather tube. The higher the cylinder pressure the more blowby you will have. Our engines are about 17 to 1 compression, thats much higher than gas engines so we normally have more blowby. You can have too much blowby indicating either a problem with gas passage around the pistons (ring malfunction) or via the head (valve sealing problem). Normal blowby for my particular engine (04.5) is 12 in. of water measured by hooking a manometer to the breather hose with a tee, one end of the tee has a hole (can't remember the diameter) to allow venting of some gases. The instructions as per cummins quickserve do not indicate if this measurement is to be done at idle or revved up, nor does it say if the measurement is to be done with or without a load. I can tell you from experience that my truck with the above mentioned tee hooked to a manometer has about 1 in. of blowby at idle and maybe 3in. at 2800-3000 rpm with no load, sitting in the driveway in neutral. Put the truck in gear and go drive up a big grade with 25-30 constant psi of boost, maintaining about 80 mph I have about 20 in. of blowby. This is more than the advertised normal, but I am making about twice the advertised "normal" hp and torque Long story short you have to vent the crankcase and you would blow out all of the seals.

 

That's what I was looking for.
So that is why there is the little crank case mini air filters, for a way to vent the pressure?
This would be the cause of the hot oil smell after running the truck hard?

 

Exactly. Jay

 

At what point does it become a problem? Losing excessive power? Oil needs to be changed more frequently? You don't have to change the oil, just add more?
And what are the solutions for it? New rings?

I'm not saying I have a problem yet, but I want to know what the future might hold.

 

Your right about being a pain to find in the search mode. I came accross your post searching Crankcase Vent. Problem was, its two words. You happened to have the two words.

Anyway, I've been driving a 2000 3500 Cummins since 2000 until last week.
I got me a CR. I was looking for the crankcase vent wanting to be sure it was not like the puke bottle in my other truck.

I think I read the collector is under the valve cover? Right or wrong? Or was that the 2003 model. So, were it be?

Thanks

Dave

 

It is under the black plastic part of the valve cover. It has a line the over and down by the drivers side of the block. Can't miss it.