airplaneman00

The overboard drain line (im assuming) coming over from the front of the motor on my 1999 2500 cummins seems to be dripping more excessive than ever. Anyone who can tell me the exact purpose of it, and if something is wrong how to fix it? Thanks in advance


steve

nitrousn

Fill out your sig so we know more about your truck.

Thats blowby from the rings. How many miles? How hard do you drive or work it.

airplaneman00

Surely will.

It has 160k, 4x4 auto. not driven hard at all and only pull light loads 2 times a month

torquefan

There is a small possibility that the oily discharge is caused by a leak in the vacuum system. The engine's vacuum pump (used for cruise control, heater operation, and 4WD axle disconnect shifting) is vented to the crankcase. This isn't a problem until there is a vacuum leak somewhere in the system. The air "sucked in" at the leak is then pumped into the vacuum pump and from there into the crankcase, then the excess air pressure exits the crankcase through the breather tube, carrying with it oil vapor. To check for vacuum leaks you need a vacuum gauge. Disconnect the main line and hook the gauge up in its place right at the vacuum pump. At idle your vacuum should be somewhere over 18 inches. Now unhook your gauge, hook the main line back up to the vac pump, and tee your gauge in to the system somewhere where you can leave the rest of the system still hooked up. The vacuum, at idle, should be within an inch of what the first reading was. If it is lower, you have a leak somewhere, and you can locate it by isolating the different branches of the system.

Hope this makes sense.

nitrousn

Would you care to explain how a vacuum pump acts as an air pump? Also where does the vacuum pump hoohk into the motors crankcase venting?

torquefan

Picture yourself pulling a vacuum hose off your running engine and putting your thumb on the end- you can feel it sucking, right? Now take that hose and stick the end in a glass of water. It will actually suck up that water until the glass is empty (if we don't hydraulically lock the vac. pump first). So where would that water end up? It would be pulled into the vacuum pump and dumped into the crankcase through the gear housing where the pump bolts to the engine.

NOTE: Don't ever actually do this thing with the water. I only used it here to better illustrate how the vacuum pump can pump into the crankcase.

nitrousn

Still makes no sense.

Contractor

Makes perfect sense to me. Where do you think that air goes that is being drawn in? It is designed as a closed system, hence vacuum, so if it gets opened then the air being drawn in has to go somewhere-- from the pump through the timing case to the crankcase and out of the vent tube.

torquefan

Picture your vacuum cleaner at home. It sucks air in one end and blows out the other. When you cover the hose end with your hand it stops sucking air in, and it also stops blowing air out the back.

cubby_23

Tell me this guys, this occurs on my 99 Dodge 24 valve turbo, when its under a load of some type, AKA towing a livestock trailer, or hauling a heavy load in the bed.
I', not sure how much is leaving, I just see the evidence on my stabilizer bar.
I dont seem to be actually losing any oil from the crank case, because it doesnt seem to be low when I check the stick. if that makes any sense?
Only had the truck for about a year, it has about 78,000 miles on it!

Thanks!

torquefan

A little bit is completely normal- if it's just some wetness on whatever the breather tube's blowing on. If the underside of the truck is soaked all the way to the rear bumper, it's too much.

cubby_23

Thanks Torque!

Geico266

Check your oil level. If it is to the fulkl line it's too full. Run it toward the lower end of the "Safe" line. This really helkps keep the blow by from making a mess.

torquefan

You're welcome.

ib516

Does your truck have the "puke bottle" on the end of the breather line? Mine does, and it is supposed to be emptied with every oil change. Maybe your bottle is full...just a thought.