7040 hydraulic 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=159893
Printed Date: 14 Apr 2026 at 12:30am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 7040 hydraulic problem
Posted By: TerronFarms185
Subject: 7040 hydraulic problem
Date Posted: 11 Apr 2019 at 11:24am
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hello all, new member, having trouble with my 7040s hydraulics, specifically piston pump. a little backstory, hydraulics have always felt sluggish, so i flow and pressure tested the pump and it was low (5gpm flow @ 2000psi, max psi 2100) so i bought a used pump but was not much better (10gpm @2000psi, 2200psi Max), i sent the original pump away to be rebuilt while i had the spare on, and the rebuilt one just came back, put it on, tried it, and it still felt suggish, so i put a flow tester on it, and the results were 13gpm @2000psi, 2200 max psi. now hydraulic guy said they bench tested it, and it tested 20gpm @ 2000psi on their bench, and max psi of 2300, where or how could i be loosing that much from being on the tractor vs on a bench stand? ive tested direct from the pump by the way, shimmed low pressure standby compensator with recommended washer springs as per the book, i thought maybe not pulling oil enough, but filters are new, checked the anti drain check valve and its all good, about to check 25psi bypass above RH filter to see if theres something there, could there be anything else im missing? how many high pressure compensator shims should there be? thats my next check. this has been driving me crazy since august
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Replies:
Posted By: critter
Date Posted: 11 Apr 2019 at 4:06pm
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Are the flow controls under the seat set to rabbit?
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Posted By: TerronFarms185
Date Posted: 11 Apr 2019 at 5:24pm
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those flows and pressures i listed were direct from the pump with the compensator shimmed straight from the test procedure in the book, bypassed the rear remotes all together
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Posted By: ryan(IN)
Date Posted: 11 Apr 2019 at 8:52pm
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AGCO hydraulic filters? Aftermarket can cause problems in these. Always use an OEM hydraulic filter in these tractors
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ryan
1984 8070 FWA,1979 7060,1975 7040,1971 190,1960 D-17D,1957 D-14, 196? D-19G, 1975 5040,1971? 160,1994 R62
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Posted By: MACK
Date Posted: 12 Apr 2019 at 7:18am
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Are the levers going all the way to detent? MACK
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Posted By: DrAllis
Date Posted: 12 Apr 2019 at 7:26am
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That piston pump is rated at 23 GPM and potentially 3,000 psi. The high pressure compensator shim stack is whatever it takes to make it develop 2300 to 2500 psi and then de-stroke itself. On an N-series combine it is actually set for 3,000 psi. Tractors are 23-2500 psi. Correct filters are a must to flow proper GPM's. Is the power steering good?? because it all starts there. I had one Customer install the right side filter backwards and it made things work funny. I was sure the pump had issues and when I scattered it on the bench, there was nothing wrong. It was the bass-ackwards filter installation causing the problems.
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Posted By: Ron(AB)
Date Posted: 13 Apr 2019 at 12:13am
A related story..
We have a 7050 that always seemed to have poor hydraulic performance since we had purchased it. It had about 4000 hrs when we got it with a rebuilt engine. The dealer assured us it was a "good" tractor. I had changed some of the hyd lever cable ends that helped some and turned the flow control, but still it was a slow machine. The only glimmer of hope was once in a while the hydraulics would really work! Albeit just for a second or two. Finally, I took those cables off and went to Princess Auto and bought two push pull cables with slightly larger clevis ends and modified the mounting bracket on both ends making it finely and accurately adjustable and easier to push. No more slop in the levers. The hydraulics work better than new!
There was just a little too much slop in the cable ends where they mount into the levers and the cables themselves are easier to push/pull with a slightly larger diameter cable. That's why we couldn't get the flow out of the hydraulics. I too, considered the pump but started with the cheapest thing first.
I should of done it 20 years sooner. Now, no one complains about the hydraulics on this tractor anymore. They're fast!
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Posted By: DrAllis
Date Posted: 13 Apr 2019 at 7:01am
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The poster has gone directly to the pump as per the Service Manual. He has taken the hydraulic valves and cables/levers out of the equation.
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