What does the "Sensor, Air Charged Crankcase Depression Valve" do?

[Gear Report]

Who can help me understand what the "25042462 Sensor, Air Charged Crankcase Depression Valve" does?
Figure-7, Item 3 Crankcase Regulator Assy.
in
TM 9-2320-280-24P-2 HMMWV M998 series Parts vol 1
Mine leaks coolant. It is just a little drip that runs down from the top every few seconds. Since I don't know what the part's function is I am clueless as to how to fix the drip/leak.
ie. will replacing the 25042462 part fix the coolant drip? Or is the coolant coming from some other problem, so it will continue to drip even if this part is replaced?

 

[Wire Fox]

Coolant? Are you sure about that? Extra crankcase pressure is supposed to flow from the oil fill tube up into the air intake. Generally you're going to get oil and maybe a small about of fuel circulating back in, which then would hopefully burn up on the next combustion cycle on the air intake. If you have a deep water fording kit correctly installed, you have an alternative unit that ties into your vent lines to use that crankcase pressure to keep the driveline pressurized to keep water from their seals.

EDIT: That unit is supposed to be sealed, except for the obvious two hose attachment points. You should have no fluid escaping. The drops there are so clear that they almost look like straight water, which makes me wonder if it's just water trapped on the rim that's escaping out. Have you only observed this once, or is it still expelling fluid after a long drive?

 

[juanprado]

That is the cdr valve. Acts like a fancy crankcase ventialtion pcv valve. Might leak oil but not coolant.

Check dipstick for choclate milk shake which indicates head gasket failure or worse cracked head/block.

 

[Gear Report]

That is the cdr valve. Acts like a fancy crankcase ventialtion pcv valve. Might leak oil but not coolant.
Check dipstick for choclate milk shake which indicates head gasket failure or worse cracked head/block.

So I thought... but there isn't coolant in my oil.
And I took that picture of the drip on January 6th... 5 months ago. Probably driven about 1,000 miles since then and checked the oil many times. Never saw any coolant in the oil. I'm baffled.
Maybe it is water and not coolant... from condensation or ??... just not from the closed loop cooling system. I thought it had the green coolant tint, but don't see that in the pic.
I'll check it again after I drive the truck this evening.

 

[Action]

Coolant hoses run near there. Check them for leaks. Or could it just be water that fell in between the hood and windshield?

 

[Gear Report]

Here is my reply from another group that describes where I think things are right now:
"...It would be fantastic if the $19 CDR is the issue.

Ah... this gets more interesting... I also have a tiny, but persistent oil leak near the front driver's side corner of the head/valve cover junction... just like Peter James mentions in the G503 discussion you shared (not linked on SS since I suspect that would be frowned upon). I've checked the torque on the valve cover bolts and they look good. Was planning on pivoting the alternator out of the way soon to get a clear look and see if the valve cover gasket needs to be replaced.
Anyhow, the oil leak might imply that the CDR is stuck, which is overpressurizing the block and causing the leak.
Unless someone speaks up with a different theory, then I will order the CDR from ebay and see if that fixes both issues."

... and the CDR was less than $18 shipped, so I ordered it.

 

[dilvoy]

The CDR's get gunked up. You might try cleaning it out with some diesel fuel if it is a non fording type.

 

[someoldmoose]

1 - PLEASE change your font so that those of us with old eyes can read it. Thanks

2 - Most likely cause is condensation. Burned fuel gases contain water vapor. Some gets past the rings on each stroke. Your device there is (as stated above) the diesel version of a PCV SYSTEM. I am not familiar with the sensor portion ( I worked on old stuff mostly ) but I would suspect there is an electronic nanny that watches the valve, probably to allow very slight positive pressure in the crankcase since diesels have no vacuum to "suck" the unwanted gasses from the crankcase. However if the pressure got too high, bad things can happen (oil leaks anywhere and everywhere). I have seen, in extreeeeme cases, front and rear seals replaced ( BIG JOBS = BIG $ $ $ ) only to be blown out again in a few miles because the crankcase vent system was not working ( That is why you MUST open the fording valve as soon as you are clear of the water ) HOWEVER, also as said above, it should be a sealed keg. If something is dripping from it, it's either a bad unit or coming from somewhere else. Dry everything off, start her up, and watch the pot boil (so to speak).

3 - If the coolant stays full (within normal limits) and the lube oil isn't turning to chocolate pudding or pouring out of somewhere it shouldn't be . . . fuggidabowdit !

My spent.

Just looked at your pic again after giving my eyes a break. That is probably not from anything to do with the valve in question. Definitely (again, said above) too clear for coolant (hope you aren't silly enough to run plain water but, Hey, I've seen it too many times) and too plentiful to be condensation from inside. Do any washer fluid lines run through the area ?

 

[Gear Report]

1 - PLEASE change your font so that those of us with old eyes can read it. Thanks
2 - Most likely cause is condensation. ...3 - If the coolant stays full (within normal limits) and the lube oil isn't turning to chocolate pudding or pouring out of somewhere it shouldn't be . . . fuggidabowdit !
My spent.
Just looked at your pic again after giving my eyes a break. That is probably not from anything to do with the valve in question. Definitely (again, said above) too clear for coolant (hope you aren't silly enough to run plain water but, Hey, I've seen it too many times) and too plentiful to be condensation from inside. Do any washer fluid lines run through the area ?

1) Not sure why it made anything I pasted in from another conversation BLACK... but I just changed it to white.
2) That is what I was thinking
3) This is an issue that I first noticed on Jan 6th... and it hasn't blown up yet. Was ordering parts for something else today and figured it was time to sort this out while I was ordering parts. Probably will blow in a few minutes when I drive it home from my son's Boy Scout meeting.

 

[someoldmoose]

For what they cost it couldn't hot but I suspect you'll see the same on the new one. Didn't someone mention the possibility of rain or other water infiltration? That's always possible too. Just that this is where you noticed it ending up. Don't think anyone classified water as a Class III leak . . .yet.