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Thread: M925 front axle will not lock in freezing temps

  1. #11
    4 Star General Jericho's Avatar
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    Mar 2012
    Landaff NH
    Thanked 502 Times in 313 Posts


    Gentleman, thank you!. this is about the best explanation i have read and seen on PPv and its effects, I moved up to the new and improved Mrap air dryer, and drain my tanks every time i use it and still get freezing ( Has been moist winter and gets as low as minus 47 F ) does affect my horn at times, does result in 150 psi and then blow off, long run on compressor no front wheel drive lock in but oddly enough wipers always work BUT changing the PPV on the wet tank and yup i do lubricate lightly with marvel air tool lube

  2. #12
    I'm the dude, man. Steel Soldiers Vendor simp5782's Avatar
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    Jun 2011
    Memphis, TN
    Thanked 6,549 Times in 2,873 Posts


    The no 6x6 when cold can result from 2 things. A froze up PPV will result in no wipers. Horn or 6x6 lock. However being that the pressure protection air lines go thru a 4 way block that supplies the transfer case with air before heading to the front of the truck. If the wipers and horn are working then it will more than likely be a froze up interlock unit that did not let air go to the front axle Engagement. Being that it's the first split in the ppv line it will get any moisture that got past the wet tank and result in a freeze up. So Ditch the thing and go to a single line system. Air to the dash switch = air to the front axle Engagement. If you want to eliminate the ppv from the front axle engagement add a T to the JIC fitting on the treadle valve port that supplies air to the shutterstat. Add an air fitting to the T. Cap the line for supply to the switch and add a new nylon line for supply. I did away with the ppv all together.
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