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DF-140A VST rfebuild

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  • DF-140A VST rfebuild

    Starting a new thread now that I have the VST out and apart. Everything looks clean with the exception of the two high pressure filters which are a nasty black color. No debris was found but when I took out the pressure regulator I discovered a gouge in the side of where the regulator sits in the case. It looks like it may have been machined on purpose but I'm not sure. Is this normal? Pic of it is attached. Also I cannot get the screw holding the valve seat out and it's becoming rounded out. I have soaked it in PB Blaster with no luck. I guess I'll have to try an easy out or just not worry about replacing the valve seat which looks OK though I would much rather replace it. Please any thoughts are greatly appreciated.
    Attached Files

  • #2
    The photo is way too close, no idea what we are supposed to be seeing.


    • #3
      That is where the pressure regulator sits in the VST and the gouge I'm talking about is clearly visible. It is 17 in the attached photo.



      • #4
        Success! After clean up and replacement of filters and the needle valve/seat the leak is gone and the motor is running great.

        1. Yes, you can take the VST out without removing the intake manifold. You do have to remove the oil pressure switch and even then it's a tight squeeze but it will come out to the top. The hard part is getting the tree bolts out that hold the VST to the manifold. Not much room and you will need a 10mm ratchet wrench - one with a swiveling head is best. It helps a lot to have a willing wife with small hands because there is little room to work. Patience is indeed a virtue for this!

        2. The VST itself is easy to work on. Both filters in mine were an ugly black so I replaced both. Replaced the needle valve and seat even though the originals looked fine. The float was in good shape so kept it and also replaced one O-ring on the pressure regulator assembly. I found a tiny bit of debris at the bottom of the tank which may have been the issue but no way to know for sure.

        3. Reassembly is easy but make sure you follow the directions in the service manual to make sure you have it right. The float height was within tolerance but I adjusted it to as exact as I could with a vernier caliper. Both the high pressure fuel pump and the regulator and associated bits were very clean but I still cleaned them with carb cleaner and then blew then out with compressed can ait.

        4. Again putting the VST back in the motor takes a lot of patience, and my case, a lot of cussing but it can be done.

        I saved about $1000 over having my mechanic put a new VST (cost about $700 for that new one) by doing this myself. Wasn't fun but not as bad as I though it would be. filled and shipped my order in record time so kudos to them.


        • #5
          Nicely done.

          I forget the history - but you DO have a water separating fuel filter on the line between tank and engine, don’t you?