Normal Crankcase Pressure

[R2.8Samauri]

Could some one please pull there oil cap off with the engine running and tell me what you hear? If you leave the cap loose with the engine running does it blow it into the air?

[R2.8Samauri]

Here is an example, just wondering if anyone elses oil fill cap behaves like this?
https://m.youtube.com/watch?v=-KjGekZDmPM

[R2.8Samauri]

Cummins responded to my question and what I am experiencing with the oil filler cap is normal for this engine.

[DieselJeep]

That doesn't look good to me. Are you wanting to try like what I always hear as the blow by test?

[R2.8Samauri]

Yes I did the test per the service manual and ended up with 12 inches, the manual said 5.8, but Cummins said not to worry until it is over 28 inches. Right now I am most worried about the smoke out the filler cap and breather. Can someone look at there engine when it is warmed up and let me know if this is normal?

[DieselJeep]

My cap flutters just like that upon startup. I haven't tried it warm yet. But it does seem unusual to me because the large engines I have don't do that at all. That being said they don't make anywhere close to the same power/torque per displacement.

I haven't seen that test in the service manual. I'll have to check it out.

Any more follow-up with Cummins on this issue?

[R2.8Samauri]

Cummins told me that everything I am experiencing with the new engine is normal. The crankcase is meant to be under a positive pressure and the oil mist out the breather or oil cap is normal. The vacuum pump also makes the crankcase pressure seem higher as it discharges into the crankcase.

[DieselJeep]

That's good to know, but it is odd compared to diesels I'm used to.

Do you think you were at some kind of extreme angle that may have contributed to the first damaged engine? My assumption and from my experience at work, that loss of oil led to a destroyed bushing. I'm wondering if this is a flaw seen at odd angles or something. I've heard of engine damage with the newer 3.6 Pentastar that Dodge uses when they're used at certain angles.

[R2.8Samauri]

I hope it was not a weird angle that caused it. If so the marketing for a Jeep is a little inappropriate. Cummins recalled the engine and are doing a failure analysis on it. Hopefully it is a one off failure. I have a very noticeable alarm for low oil pressure on my digital dash and have never seen it come on at weird angles.