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Water crossing idea...

Discussion in '40- & 55-Series Tech' started by 74cruiserintexas, Dec 31, 2002.

  1. 74cruiserintexas

    74cruiserintexas

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    I dont know if this would work or not but.....what if you run your axle vents, a distributor vent..etc to one central vent...then when you make a deep crossing you can pressurize thru the vents with approx 2 to 4 lbs of pressure..so it would force air out instead of letting water in...
     
  2. PHAT MAX

    PHAT MAX

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    keep it low....you dont want to blow the seals out

    edit: by low i mean low pressure.
     
  3. teat

    teat

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    yeah real low
     
  4. shelfboy1

    shelfboy1

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    military has been doing that for many years.
     
  5. Brian in Oregon

    Brian in Oregon

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    As noted, the pressure has to be kept low or it will not only blow lube past the seals, it can actually blow out a seal.

    Most military fording systems run vent lines from the axles, transmission, transfer case and fuel tank to a line running from a PCV valve. When a fording cable is pulled on the dash, it cuts out the PCV from feeding back to the carb. Instead, the engine blow-by is used to pressurize these parts, since it is low pressure. This also pressurizes the engine as well. This system works quite well, and the military delighted in taking photos of various vehicles ranging from jeeps to big 6x6s being totally submerged in a water tank with only the intake snorkle and exhaust pipe showing, running underwater for hours.

    If you're going to run an air source to pressurize these components, I'd suggest installing a regulator that limits the air pressure to 1.5 lbs.

    If you're not doing a lot of fording, and not deep fording, it's simpler to just run the vent lines to a single line and run it to the top of, say, the roll bar and install a small filter on it. The cold water will condense the air in the components, but this line will simply provide air into the vacuum, instead of water being pulled past gaskets and seals. If your gaskets and seals are bad, this is not an option, though.

    One issue is the clutch. If you're doing deep fording you should not be shifting or engaging/disengaging the clutch while in the water or you'll get water on the face and it will slip. Military clutch housings are sealed, except for a drain plug, which is inserted before fording.

    And the fan. Fan blades, especially those on flex fans, can be pulled into the back of the radiator with disasterous results when they strike water. Military jeeps had a lever to release tension on the fan belt so the fan would not spin (and the water pump wouldn't either). An electric fan can simply be turned off. I've wondered about making a round metal guard that would intercept any blades being pulled into the back of the radiator. So far this has not been an issue since I've never forded over three feet of water, but could in deeper water.
     
  6. Mark W

    Mark W

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    A clutch fan will not transmit enough force to deform the blades. And you don't have to turn it on and off all day long.

    For deeper fording we have found that water often pushes past seals even if they are in good condition.

    It would be simple to plumb a pressurized system that would maintain a couple PSI over whatever pressure the water is creating against the outside of the seals by locating the bleed off line from the relief valve at the same level as the axles.

    Mark...
     
  7. FJ40Jim

    FJ40Jim The Cruiser Whisperer

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    Another self-regulating low pressure source used on some military rigs is the backside of the fuel pump diaphragm. The top of the diaphragm makes a few PSI of fuel pressure, and the bottom of the diaphragm makes a few PSI of air pressure.

    Just sumthin' to consider.
     
  8. Fast Eddy

    Fast Eddy SILVER Star

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    Good idea. You'd need about 0.45psi per foot of depth for equilibrium.