AC HD4 Hydraulic pump identify
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=140684
Printed Date: 02 Aug 2025 at 11:15pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: AC HD4 Hydraulic pump identify
Posted By: johnP
Subject: AC HD4 Hydraulic pump identify
Date Posted: 22 Jul 2017 at 9:13am
Could anybody please help identify Pump on my HD4 it is leaking a little and causing it to chatter when using the hydraulics. I would like to reseal it if the parts are still available. This is what it looks like. It is leaking between the cast and aluminum sections. 
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Replies:
Posted By: DMiller
Date Posted: 22 Jul 2017 at 3:48pm
| That is most likely a previous patch repair. Do not usually or casually mix aluminum and steel housings as they expand at different rates. I would look for a whole pump to get rebuilt. |
Posted By: Josh H
Date Posted: 06 Aug 2017 at 12:04am
| You probably already know but thats two separate pumps that go together. If i remember right one towards operator is shuttle and other is hydraulic. If i understand right, you're saying its the gasket between the two. Separate fairly easy, splined shaft |
Posted By: johnP
Date Posted: 07 Aug 2017 at 11:39am
| Ya I thought the same thing because rear pump flows through the filter up front, I'm just wondering if its a o-ring and still available. I dont use the machine to make money or anything its just for around the yard and I run a splitter for firewood so I really don't want to replace the either pumps. |
Posted By: johnP
Date Posted: 09 Aug 2017 at 5:07pm
Thanks for all the replies, I removed both pumps and there is no orings. However the seal for the output shaft of the hydraulic pump was leaking causing the fluid to exit between the two pumps. seal is CR 545294
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