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CA Hydraulic Pump Prime Loss

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=212256
Printed Date: 16 Sep 2026 at 6:41pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com


Topic: CA Hydraulic Pump Prime Loss
Posted By: dfwallis
Subject: CA Hydraulic Pump Prime Loss
Date Posted: 16 Sep 2026 at 3:55pm
I know that the system has thicker oil than specified (30wt vs 20wt), because the NAPA guy didn't give me what I asked for when I backed the truck up to the dock.  It is just a little slow to prime and sometimes loses prime when in hold or down (it's a 1952 and doesn't have the inlet check ball that some possibly later ones had).  It also has a leak around the plug at the top rear of the pump.  I think either the rebuilder didn't include the crush washer or it needs a new one.  I'll try to fix that next trip.  Could a leak at that plug contribute to loss of prime (it doesn't squirt but is a fairly constant dribble under pressure)?  I've mostly resolved the cylinder leaks.

After the first of the year, I'll probably change out all the fluids and correct the viscosity issue.


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1952 CA13092, CA Pickup Plow, CA Cultivator, CA Two Row Planter, Dunham-Lehr GC78 Disc, Grader Blade, 3pt Fm180 Finish Mower



Replies:
Posted By: steve(ill)
Date Posted: 16 Sep 2026 at 4:23pm
any air inlet leakage can cause a loss of prime over time.. Make sure the oil level is UP TO MAX also... I have a B that i run an inch over the level mark to keep the pump primed when i travel DOWN steep hills........ i added a 45 degree elbow to the fill port and  fill to that top instead of the threads in the trans case..

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


Posted By: dfwallis
Date Posted: 16 Sep 2026 at 4:47pm
Originally posted by steve(ill) steve(ill) wrote:

any air inlet leakage can cause a loss of prime over time.. Make sure the oil level is UP TO MAX also... I have a B that i run an inch over the level mark to keep the pump primed when i travel DOWN steep hills........ i added a 45 degree elbow to the fill port and  fill to that top instead of the threads in the trans case..

I topped it off last trip and it improved slightly.  It was only about a 1/2 cup low though.


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1952 CA13092, CA Pickup Plow, CA Cultivator, CA Two Row Planter, Dunham-Lehr GC78 Disc, Grader Blade, 3pt Fm180 Finish Mower



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