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289 oil pump wear

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  • Engine: 289 oil pump wear

    Most of main engine components off to the machine shop, so I thought now would be a good time to pull the oil pump apart for cleaning. I wasn't expecting much wear, or any wear at all, since they sit in oil all day long. Lo and behold, significant wear on the inside of the cover plate.

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    This was odd. I have taken a few of these gear driven oil pumps apart over the years. Never seen wear like this( a 50 year old Y-block with an external gear oil pump didn't have wear like this). I checked the gears on this pump and saw no wear on the teeth where they would come in contact with the cover. Per the manual, I found less than .007 between the pump body and a straight edge placed over the body and gears. The side gaps were also with in spec.
    Checking the shaft of the driven gear and it's bore, I found some play, but nothing alarming. Possibly a worn bore allowed the gear to cock and wear in the half-moon on the cover. The other possibility, though I think this would be remote, is that the drive shaft between the bottom of the distributor and the oil pump was somehow exerting pressure on the driven gear.

    Given that everything is within spec, I was planning to buy a replacement cover from SI. But I was also wondering if the engine builders and rebuilders on the forum had come across this wear and if they were also to sleuth out an answer to what caused it.

    Many thanks in advance.

  • #2
    My assumption is very simply that the weight of both gears which are allowed to rest on the Plate does this, they ALL have this wear.
    How deep, depends on how many Hours or Miles the Engine has run and the quality and cleanliness of the Oils that have been used.

    Your best bet is to buy the Complete Studebaker Vendor Repair Kit with all New gears, shafts and cover since you have wear on Both Gear SHAFTS, but not the Pump Housing, which is a VERY Good thing, since those have not been available in years.
    Second Generation Stude Driver,
    Proud '54 Starliner Owner


    • #3
      I'd bet that "IF" you could actually measure the depth of the scratches, that they actually aren't that deep, nor are they that "off-center".
      While t is hard to tell in a picture like this some wear is normal. Also, I'd bet most of it comes at cold starts.
      Plus, yes there is a radial gap, shaft to housing. The loads on the gears from the oil being forced into the small holes in the pump/engine, will put as much a side load as can be done on the gears/shaft.

      Question - is this pump off of a full flow or a sorta flow filtering system ?



      • #4
        As already said, that's not serious wear. CASOs can use emery paper on a flat surface, polish out the scratches, give the bottom of the gears and the bottom of the pump body a similar polish, set end play per Shop Manual and you're good to go.

        For a few dollars more, as Rich suggests, go with the repair kit and have all new parts.

        jack vines


        • #5
          Mike, you can catch a thumbnail on the wear ring on the left. Not so on the right. It's a sort of flow. Grandpa ( of the guy I bought engine from) put about 70,000 miles on it. Should say it's a truck engine,, 1959 vintage. Everything is being checked at the shop, and so far, no abnormal wear.

          Good to hear, Jack, that it!s not serious wear.

          Rich, makes sense the weight of the gears caused the scratches. They are hardened and have some heft to them. I've been told I overthink things. probably so here.

          thanks all.


          • #6
            Ok no one's gonna say anything about the lovely Christmas background on the Oil pump cover? That wear looks pretty normal to me. What do the sides of the pump body look like? If there is no heavy scarring on the body and gears go ahead and run it. Merry Christmas!


            • #7
              Put it on a surface grinder and grind it flat. Don't have a surface grinder, send it to me and I'll do it for you.



              • #8
                I see wear like this on rear pumps from power shift and flight o matics. I use a chunk of salvaged marble counter top, with 120 or 220 grit wet or dry sandpaper to level the cover surface out. The surfaces from the factory often is/was not very flat. You can use solvent or WD 40 to lube up the sandpaper while you are smoothing it out. Lou Cote


                • #9
                  Mine looked just like that before I used my surface grinder to make it flat again. Even though I could only measure about .003”, it took .011” to clean up. I’ll be glad to resurface it for you. Neal


                  • #10
                    Neal, JT, thanks for the offers. I went ahead and ordered a new cover from SI. $15 for it, and was ordering some other stuff anyway.

                    Lumpy, Lou, gears look fine and sides of pump body look good. Per manual, less than .010 total between gears and sides.

                    I got a bit of "the look "when I put the cover on the dining table for the pic. I promised it was clean, clean, clean.

                    thanks again all.


                    • #11
                      I have taken them to the machine shop and had them planed nice and smooth. It's cheap too!