mcdougall Posted December 28, 2017 Share Posted December 28, 2017 Hi I am looking for help/advice for rebuilding worn oil pump for my 1925 master engine. Are replacement gears available,or would anyone have a good replacement pump for sale? I am based here in Scotland so parts and advice are thin on the ground. Wishing all forum members a good Scottish new year. Regards alex mcdougall 1 Link to comment Share on other sites More sharing options...
Jim Bourque Posted December 29, 2017 Share Posted December 29, 2017 Alex I rebuilt my pump a few years ago using Melling part number K-64 Jeep gears. It will require some pump housing machining. Attached is what the machine shop will need to modify your pump housing. The shaft will need to be modified as well. Hope this helps Jim Jim 1 Link to comment Share on other sites More sharing options...
Hubert_25-25 Posted December 29, 2017 Share Posted December 29, 2017 Alex, My 1925 Standard oil pump really just needs a new bottom brass plate. No wear on the gears. It needs a new relief spring as well. I am just going to get a new plate of brass for the bottom and drill holes to match the old plate. I will grind out the "oil reservoir" in the middle of the plate. I also need to have a relief spring made to the specifications in the shop manual. Hugh Link to comment Share on other sites More sharing options...
Guest Posted December 29, 2017 Share Posted December 29, 2017 Why do you need a new brass plate. A few minutes with polishing in figure eights on a piece of emery paper or valve grinding compound on a piece of plate glass should make the original as good as new and you are sure that it fits. Link to comment Share on other sites More sharing options...
sligermachine Posted December 29, 2017 Share Posted December 29, 2017 (edited) try adding a washer to the spring that might test good are u using a spring gauge or trying to push air for a test that is all u ever do to a air plane oil relief valve. Just lap it on a plate thats all I would do too kyle Edited December 29, 2017 by sligermachine (see edit history) Link to comment Share on other sites More sharing options...
DonMicheletti Posted December 29, 2017 Share Posted December 29, 2017 Be sure to check the geat to cover end clearance. It is important. Link to comment Share on other sites More sharing options...
dibarlaw Posted December 29, 2017 Share Posted December 29, 2017 On my standard that was all the pump needed to get the plate flat again. After that lapping 25 lbs. of pressure on a very worn engine was not to bad. I pulled the pump out of the spare 1924 6 cylinder engine with hopes of rebuilding it for use in the 1925 Master. The plate on that one the driving gear wore a pretty deep circle on the plate. One edge at about .040 deep. The problem is the driving gear shaft and its bore are worn over .012. Also the integral cast shaft for the idler gear is also worn about .005 under. According to the Master Parts Book These pumps should be the same for 1924 (6) through 1928 Masters. 1 Link to comment Share on other sites More sharing options...
mcdougall Posted January 11, 2018 Author Share Posted January 11, 2018 Hi many thanks to everybody who responded to my oil pump enquiry,much good advice here. Many thanks to you jim borque for your solution to use jeep gears, Jim how did you overcome the problem with the different shaft centres? Are there any differences between the 1924/25 oil pumps,the parts manual for the 24 shows a spring on the drive shaft,my pump does not have this. I am still looking for a spare pump that I can recondition,if anyone can help. Regards alex mcdougall Link to comment Share on other sites More sharing options...
Jim Bourque Posted January 12, 2018 Share Posted January 12, 2018 Alex The driven gear shaft that is part of the pump housing need to be machined off. The drive gear side of the housing needs to be bored and a brass sleeve bearing pressed in and sized to fit the Jeep drive shaft. I left the brass sleeve bearing about 3/4 of a inch above the pump housing for more bearing surface. Once the center of the drive shaft is established, you can then locate to driven gear center. Bore pump housing to an interference fit to the drive shaft dimension. Use a short piece of the drive shaft and press into housing. The gears will also need to be shortened to match the depth of the housing as well as the housing will need to be bored to fit the gear diameter. Stick the bottom plate to a surface grinder with double sided tape and grind flat. Make an adaptor to connect new pump drive shaft to the original intermediate that sits in the engine block. My freshly rebuilt 25 Master holds 25 PSI on a 90 degree day at idle running 0/20 synthetic It's been a few years since I did mine, but has been working beyond my expectations. This was my workaround as serviceable used gears don't exist, having new duplicates made by a gear shop would have been about $2000.00 for the first set and would have dropped to something reasonable at 20 sets and the drive side of the pump would still need to be sleeved as well as other wear in the housing that could not be repaired. Jim Link to comment Share on other sites More sharing options...
mcdougall Posted February 2, 2018 Author Share Posted February 2, 2018 Many thanks to jim bourque for explaining how to machine buick oil pump for jeep gears. Regards alex mcdougall Link to comment Share on other sites More sharing options...
Hubert_25-25 Posted February 3, 2018 Share Posted February 3, 2018 As a follow up, there were several people that commented on my oil pump end plate, that I only needed to surface the plate. I wish it were so simple, and I had 2 machine shops that were not able to understand the problem or provide any good advise. The problem with my plate is that the circle cut into the plate is not flat on the drive gear, but rather worn deeper on one side of the wear circle than the other. I still need to surface the end plate, but it needs to be done professionally, as the wear is too deep and severe. Larry DiBarry gave me good advise as usual, and the culprit is that there is wear on the shaft of the drive gear and the oil pump housing. The drive gear needs a bushing installed and this will keep the gear flat to the end plate. I sent my pump off to Egge Machine, and they will be installing a bushing and pressure testing the pump. Hugh 2 Link to comment Share on other sites More sharing options...
mcdougall Posted February 3, 2018 Author Share Posted February 3, 2018 Thanks hugh for this good advice . ALEX Link to comment Share on other sites More sharing options...
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