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Thread: oil pump

  1. #1
    Junior Member capyjack's Avatar
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    oil pump

    Hello again,
    Today I have oil pump and pressure concerns.
    This is a 1948 Jeepster with the four cyl. Go Devil.
    Its making way to much oil pressure and the relief system in the pump is nothing like shown in the manual.
    I have confirmed with a known good mechanical gauge that the oil pressure is at around 55 lbs hot or cold, idle or driving.
    I am going to attach a couple of pictures.
    Note that there is a ball and spring but no shims. The manual shows a relief plunger, not a ball.
    Also note that the ball shows a ring that makes me think that it is not coming off of its seat. The retainer compresses the spring rather tightly and I suspect that the pump is supplying full pressure all of the time.
    KW does not show these parts available individually. But I would like to find the proper parts. Plunger, spring and shims.
    Thanks all in advance, Jack
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  2. #2
    Super Moderator gmwillys's Avatar
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    The relief spring only works at higher RPM. You are correct that there isn't a good source for rebuild kits for the pump. It looks like your pump may have been put together from the spare parts bin. Without a shim installed, it will be difficult to even try to adjust the pump. You could try a Napa, and see if they have a kit, or a shorter spring.

    My biggest concern would be a possible spun bearing. That is a worst case scenario. A spun bearing can cause a constant restriction, that would not allow the pressure to drop enough to notice on the gage. I would take a close look at the oil to see if there is any evidence of metal. If none is found, then I would try to do something with the pump.

  3. #3
    Junior Member capyjack's Avatar
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    I agree that it looks like it was assembled from spare parts.
    I hadn't thought of a bearing blocking flow. But makes sense.
    I have put some trouble free miles on the thing so I doubt that's it but I will drain the oil and take a look.
    I thought I would post a parts wanted ad for these small parts in the classified forums, but for some reason I cant log into that forum.

  4. #4
    Super Moderator gmwillys's Avatar
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    I doubt the spun bearing as well. It sounded like you had been putting miles on, so if nothing has shown up to this point, just look at the drain oil to ensure that there is no issues.

    I've never tried the classified forums, so I'm no help there.

  5. #5
    Super Moderator LarrBeard's Avatar
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    A. It doesn't work right.

    B. That means it's broken.

    C. As my A-school Chief taught us; God hates cowards. let's try to fix it.

    D. Trim the spring a half-turn at a time. That will release pressure on the make-shift ball check valve.

    E. By the time you cut a couple of turns off, you should see some reduction in oil pressure. If not - oops, look elsewhere. Keep looking for a different pump. Even a junk one should have a spring and plunger.

    And, I heartily agree - look at the oil for metal flakes. Engines should not make metal. That's why aircraft engines and helicopter transmissions have chip lights (magnetic metal detectors) to keep track of stuff like that in the oil. A couple of years ago, FiFi, the CAF B-29, had to sit for a year because two of those gawd-awful huge radial engines started to make metal.

  6. #6
    Junior Member capyjack's Avatar
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    OK, no sign of metal in the oil, clean and no bad smell.
    It may be a pretty heavy weight but I had to drain it cold.
    My thoughts on cures go pretty close to what LarrBeard suggests. I have to compress the spring about .100 before I can catch a thread on the plug. But I have about 1/2 inch of those 5/8 threads.
    I am going to stack a few 5/8 flat washers on there with a new fiber washer so that the plug is shimmed out. I don't think I will drive it that way but I may learn something if relieving that spring that far lowers the pressure.
    Worse case if I don't find parts is a new pump. I am not one that throws expensive parts at things but a new pump would be an out.
    However, another part of the mission is to rebuild the heat riser in the exhaust manifold as I guess this is the only manifold that fits this engine. There isn't a manifold that eliminates the riser like on the later engines. (I might buy one of those if it was that 90 dollar one)
    I am getting what I feel is to much exhaust leaking from around the shaft so the manifolds are off and I have to order the riser kit and some gaskets.
    I suspect that it will be at least a couple of weeks before I can get back on this.
    Talk then.
    Thanks, Jack

    Later, Now that I think of it, I will most likely be seeing some oil leaking between those washers. I will make a shield.
    Last edited by capyjack; 02-09-2019 at 08:47 PM.

  7. #7
    Super Moderator gmwillys's Avatar
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    You can use Teflon tape to seal the threads, enough to determine the needed alteration needed for the spring.
    I agree that we should not be parts changers instead of trouble shooting the problem. Some parts aren't expensive, but they add up in time.

  8. #8
    Junior Member capyjack's Avatar
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    Yes, no problem on the threads. But I doubt a stack of washers will be very pressure proof. And with only one or two threads holding I wont be putting much torque on that cap.
    I am anxious to get my manifold fixed up and get this engine fired up again.
    I will order parts on Monday. I have a credit and have to order by phone to access it.

  9. #9
    Junior Member capyjack's Avatar
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    If the guy from Nevada happens to find this ad, or if you are the one that gave my number to him. Probably thru the classified ad I posted but cant seem to send a reply.
    Call me again as I am interested in the pump we talked about. I tried to call you back at the number you called me from but it seems to be disconnected.
    Thanks, Jack
    5O3 538,eight six fortyfive.

  10. #10
    Junior Member capyjack's Avatar
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    OK, Hello all,
    I did hear back from the one caller that I got about an NOS oil pump however we couldn't strike a deal, He had a bunch of misc. engine parts for sale as a whole lot and wouldn't ship.
    Last we talked he had to get the stuff gone and was going to take it all to the scrap yard.

    I have now rebuilt the heat riser in the exhaust manifold and put a lighter spring on the oil pump.
    This solved many problems, no more exhaust leaks at the riser and the oil pressure has been tamed.
    I bought the Jeepster as a bit of a favor to a friend, it was in mid project and no one in the family had the wherewithal to finish it.
    I did agree to offer it up to the sellers family when I got it done and have now given them a reasonable price and thirty days to decide.
    Therefor it may be for sale to the public at the end of March. It will probably be available at the Portland swap meet unless the family decides to pick it up.
    In the mean time if anybody wants to be on the 'next up' list give me a call at the above number or send a message.
    Its a nice little car that came out quite well.
    I may consider a swap for a military type Jeep. or possibly Mopars from the late twenty's to mid thirty's. I don't mind light projects, but don't need any major projects.
    Thanks to all here on the forum that helped me out with this project, it has been fun. In particular LarrBeard and gmwillys.
    Cheers to all, JACK

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