How Much Psi Is Too Much

I have on board air on my Jeep and I was thinking of putting a valve to pressurize the differentials and transmission and transfer case. I was thinking of 5psi to pressurize them for deep water. Is that too much?

 

M38A1 used unregulated pressure from the crankcase but I don't know what that would be. I'd be interested to find out.

According to this thread, M35 used regulated air at 4 psi.
Home Made Fording Kit? - Page 3


Be aware, as they point out, the military protocol called for major overhaul work after each deep-water fording, even with sealed and pressurized systems.

 

static water pressure is roughly 4 PSI/10 feet..

 

how much deep water do you drive through?
for a trail rig I would say a good working vent is all you really need...
for an apocalypses vehicle... maybe, but again bigger concerns..

 

Exactly, make sure the vent hoses are in good shape and routed to the top of ther firewall or even up under the dash if you're paranoid.

 

Just figured the military jeeps had that feature. Thought it would be a good idea.

All my vents are up high anyways.

 

Would you include the carb, fuel tank, and the distributor, plus sealing the alternator, regulator etc, as the M38A1 did? Probably be easier just to buy a military jeep.

 

If I'm that deep, its probably someplace I don't want to be. The deepest I'm comfortable with is up to the floors.

 

If you axles, transmission, transfercase are all sporting high terminated vent lines, I think the only thing that you are going to accomplish by pressurizing is the increased time spent replacing the seals. Those vent lines have already eliminated the negative pressure associated with rapid cooling. Floor level water depth is way different than completely submerged. On my B, I terminated the vent lines just below the hood and made filter caps for them that should "air lock" if they do get a short, intermittent submergence. They are similar to the vent on my York but with a hose connection instead of the o-ring fitting:

 

If you were to pressurize your axles and trans/xfer case, I would regulate them to no more than 1 psi. I think even this might push gear oil out the various seals depending on how the vents are regulated.
I have had great luck just running vent lines up to the cowl under the windshield.
-Donny

 

The military Fording system is controlled by a manual valve, to be pressurized only while in the water.

 

The m38 didnt pressurize the axles. Only the transmission and transfer cas . The axles had a one way vent on them