I'm new to the forum and to diesel.motors in general.. I'm getting some blow by out of the oil cap but not out of the blow by dump tube pointing down on the left side of the motor. I also can't get my 4x4 to engine, not at the tcase but the vacuum portion of of.. Thanks in advanced. Not too sure how attach a video to help

 

Well,

First of all you will need to check all your vacuum lines- on the left side of the engine there is a vacuum pump, follow the single hose coming from it to the firewall, it will branch into multiple lines and plugs from there. All of this needs to be tight, not cracked and in good order.

The "oil-cap test" is not really good on the cummins. If your blow by tube is not blocked by something the oil cap test will give you a lot of noise and oil fumes compared to a gasser for a simple reason.
On a gasser you have a connection from the crankcase to the intake runners that has a lot of vacuum while at idle- and the diesel does not have that. It also has no throttle, almost no intake vacuum and the 12V has no PCV. So comparing what you see at the oil cap with any gasser built after WW2 will throw you off.
The vacuum pump on the Cummins has an exhaut into the crankcase, so any leak in the vacuum system that is used by the cruise control, the air conditioning and the 4WD system, will show a lot of air exiting the blowby tube (or the oil cap if you open it)

But this does not say your engine is worn beyond service limits!

HTH

 

Sounds like a vacuum leak. The vacuum pump draws no air inlet as its working under a vacuum, but when there's a leak the air allowed to enter the pump will exit into the crankcase and come out the blowby vent hose.

You'll want to pick yourself up a vacuum test gauge (doesnt have to be expensive), and test all the vacuum lines. The vacuum pump will typically generate about 20-25 in.

 

Thanks for the responses guys. I'll check the lines this weekend for cracks and wear.. does Harber freight carry testers like that?

 

I'm sure they do.

 

A good and also otherwise useful thing is a mityvac like

 

OK guys, I checked the lines and they seem to be in good shape. I've found out that my 4x4 is cable actuated not air anymore. Someone must've switched it over.. the vacuum pump is attached to the power steering pump correc? If so, there's quite a bit of residual oil (I think) all over the thing. I tried looking above it to see if something else is and couldn't find anything.. so at this point, should I take that pump out and inspect it?? There is a lone going towards my transfer case that goes no where and also 4 lines on top of my tcase that go know where. Not really sure what those are for

 

The 4 lines that go to (or used to) the modular plug/switch on the top of the t-case near the shifter is what used to operate the axle disconnect. So, there was a line coming off your main vacuum line that fed that switch (vacuum harness) which is not needed and should be plugged at the "T". Right now all the transfer case needs is the 1/4" vent line. That is separate from the switch, connects to a nipple right in front of the switch.

Your vacuum pump should connect to the power booster (if equipped) and/or to the HVAC controls, that's it.

Testing your vacuum pump and lines with a mighty vac will help you find any leaks, including the pump itself.