Farm Equipment - Allis B oil pressure problem

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Allis B oil pressure problem

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=202052
Printed Date: 04 Jul 2024 at 1:21pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Allis B oil pressure problem

Posted By: JudgeguyBob
Subject: Allis B oil pressure problem
Date Posted: 30 Jun 2024 at 12:07pm

I have a 1940 Allis Chalmers B. Engine totally overhauled. Oil pressure pump rebuilt.

When reinstalled on the tractor I primed the oil pump via the tube from oil filter base to the oil pump. Tractor started right up, oil pressure gauge ran right to the normal range and stayed there while tractor was running. Overnight oil pump would lose prime and if primed again would show normal pressure as long as the engine was running. Tightened all the fittings, with no improvement. Pulled the engine and flywheel, went over the oil pump, resealed the gaskets, replaced a fitting on the oil line from oil pump to cylinder head. Same result as previous. Replaced the tube through the oil filter and installed a new Wix 7011 oil filter. Oil pump still loses prime over night. Once it's primed the engine runs well with oil pressure with the needle staying stable in the normal range. What am I missing? Thanks for any advice or help! Bob

Replies:

Posted By: PaulB
Date Posted: 30 Jun 2024 at 12:36pm

I have been working on these BE/CE engines since the late 60s. The reason that you loose prime overnight is: The check/pressure relief ball in the oil pump is not seating properly. If you got a pump rebuild kit or if you just did the work with what you have rebuild, you should always put the ball into the rotor and with a brass punch and heavy hammer, give the ball a good wack, then throw that ball away and assemble the pump with another NEW ball.

I have seen many work with what you have rebuilds that have a small rust spec on the ball and most all the time thins are just fine, then every once in awhile that rust spec get into just the right place to allow it to loos prime.

Another thing to look for is a very fine crack in the threads of the oil screen holder., or mangled threads on either end of the pick-up pipe. Any thing that is not air/oil tight will allow loss of prime.

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If it was fun to pull in LOW gear, I could have a John Deere.
If you can't make it GO... make it SHINY

Posted By: JudgeguyBob
Date Posted: 30 Jun 2024 at 1:10pm

Thanks, Paul! That all makes sense. When I have time and help, we'll pull the engine and flywheel and go over the pump with special attention the ball and other things you mentioned. Comments much appreciated!!

Posted By: HudCo
Date Posted: 30 Jun 2024 at 10:58pm

pick up tube haas a crack i think it is a 3/8 x 9 pipe npt threads

Posted By: JudgeguyBob
Date Posted: 01 Jul 2024 at 4:35am

Thanks! I'll check that out.

Posted By: Lon(MN)
Date Posted: 01 Jul 2024 at 12:46pm

Had that same problem last week. Complete rebuild on the engine and new parts in the oil pump. I took the engine out three times and the pan off. I could not find a problem. I took a used pump off the shelf, put it in and the prime loss problem went away.

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http://lonsallischalmers.com

Posted By: juniorp53
Date Posted: 01 Jul 2024 at 1:10pm

any imperfections in the ball and seat will cause loss of prime every time .... just replace the ball its nothing special just a plain 5/16 ball bearing mcmaster has them .. i cant for the life of me understand why any of the rebuild kits dont include one for the amount of grief not replacing it causes

a new rotor still available

you can also search here on the forum as this same subject is mulled over every few months