Changing fuel filter Cummins X15..

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Concorde, Dec 28, 2025.

  1. Concorde

    Concorde Road Train Member

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    Just did my oil, fuel filter, Davco and grease yesterday.

    I removed the fuel filter, completely drained the Davco. I’m a little loopy about getting everything, sludge etc from the bottom of the Davco. Put the Fuel filter back on dry..all while thinking to myself this isn’t going to be easy, lol.

    Put the new Davco in and filled it up with fuel.
    Cycling the key 3 times adding fuel as it rapidly dropped. Added almost two gallons of fuel.. did nothing with the vent.

    Cycle the key the 4th time and fired it up. It started right away as normal. Absolutely no extra cranking.

    Now the tiny power steering filter ended in a complete disaster, haha.
    Didn’t realize that small reservoir held so much ATF!! Ruined my favorite jeans and made a complete mess.on the pavement. I pulled the lower hose while holding a small catch container but it failed miserably.. Most everything I learn is the hard way!
     
    Diesel Dave, D.Tibbitt and wore out Thank this.
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  3. AModelCat

    AModelCat Road Train Member

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    Manufacturers have been discouraging prefilling fuel filters for a while now.

    The big thing is keeping contamination out of the system and prefilling filters has the potential to introduce a ton of contaminants into the system. These new fuel pumps used on high pressure common rail systems operate on a tolerance of a couple microns and the fuel out of a jug or siphoned out of the tank is no where clean enough.
     
  4. Concorde

    Concorde Road Train Member

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    That’s something that really needs to be addressed to owner operators who use truck stops for their PM services. All I have dealt with in the past pre-fill the fuel filter. Eventually it could get costly or already has and the culprit is never known.

    Thanks for chiming in.
     
    Diesel Dave, wore out and D.Tibbitt Thank this.
  5. Ruthless

    Ruthless Road Train Member

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    I been hosing a can worth of brake clean thru the davco housing with the puke valve open every time I swap that. Always something in there/ I can’t see changing a filter to leave #### in the housing for it.

    mine says to pre fill the secondary, same as the directions on yours- it says leave the plug in the center and prefill the outer holes. Doesn’t say put it on dry.

    the lift pump will fill it; imo better off using the freshest of fuels to pre fill the filter as directed
     
    JB7, Diesel Dave and Concorde Thank this.
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