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Oil priming a c oil pump

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=209807
Printed Date: 22 Jan 2026 at 2:41pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com


Topic: Oil priming a c oil pump
Posted By: 3rd generation
Subject: Oil priming a c oil pump
Date Posted: 21 Jan 2026 at 1:15pm
Just about to start a freshly rebuilt 1944 C engine.
My thought is to use an oil extraction pump to push oil into pump and engine. I could use the pump for my boat motor if it doesn’t work.
Is primming these pumps needed considering the pump does not sit in the oil pan.
I resurfaced pump to .0025”



Replies:
Posted By: steve(ill)
Date Posted: 21 Jan 2026 at 5:35pm
it may prime on its own... but you can take the 1/4 inch tube off going to the filter and use a squirt gun to fill the tube and pump prior to cranking..

remember, this is a BYPASS System... you dont have to FILL the filter.. The pump pushes 85% of the oil thru the cam shaft to feed all the engine bearings... 15% of the oil goes to the filter to clean and dump back to sump..


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Like them all, but love the "B"s.


Posted By: HudCo
Date Posted: 21 Jan 2026 at 6:31pm
i use a weed sprayer to pre lube all my new engines i just hook into the oil preasure gauge port mostly


Posted By: Les Kerf
Date Posted: 21 Jan 2026 at 6:55pm
DickL has posted his method which is to remove the oil filter and slip a snug fitting hose over the metal tube that Steve described above. He then uses a small funnel to fill the hose and lets it gravity feed down, maybe repeating this a couple of times. Then, leaving the valve cover off, allow the hose to hang into the valve area in order to verify that oil is actually flowing upon initial startup. This method also provides for observing the flow of oil to the rocker arms.

I only recently learned of this method, but I intend to do this on my next fresh startup.


Posted By: 3rd generation
Date Posted: 22 Jan 2026 at 7:57am
Good info. Under normal flow does the oil exit the stand pipe from pump?


Posted By: Les Kerf
Date Posted: 22 Jan 2026 at 8:20am
Originally posted by 3rd generation 3rd generation wrote:

Good info. Under normal flow does the oil exit the stand pipe from pump?

Yes.
As Steve mentioned above, the majority of the flow goes through the hollow camshaft to the internal parts of the engine (weird, huh?) and roughly 15% is diverted to the oil filter and governor drive via those external oil lines.


Posted By: steve(ill)
Date Posted: 22 Jan 2026 at 9:13am
If you just TAP IN to the line, most of your aux pump oil will go thru the filter and dump back to sump... You dont need oil toward the filter, you need to push the oil BACKWARD thru the tube into the PUMP and hollow CAM..

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Like them all, but love the "B"s.



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