Hydraulic Pump Help Please - Allis 7000
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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=161976
Printed Date: 12 Feb 2025 at 3:18pm
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Topic: Hydraulic Pump Help Please - Allis 7000
Posted By: Play Farmer
Subject: Hydraulic Pump Help Please - Allis 7000
Date Posted: 17 Jun 2019 at 7:14am
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Good morning. I need some help and/or your opinions. Take a look at the attached picture. This is on my 7000 Maroon belly. It started leaking hydraulic fluid so I took the pump off and found what you see in the picture. The o-ring was also a little brittle so I assumed this was the smoking gun. I replaced the o-ring, put it back together and went back to work. I mowed some hay yesterday afternoon, it worked well for about 2 hours - now it's leaking again. I haven't taken it off yet but it's leaking from the same spot so I expect to find the same issue. I'm using a nitrile o-ring in a petro-based hydraulic fluid so I don't think chemical attacked is the issue. Other than the leak it's working awesome. Any ideas on why the failure so soon after the repair? Bad luck, coincidence, cap loosened up, or an internal issue over pressurizing the pump? Any comments, suggestions, ideas? Thank you in advance.  |
Replies:
Posted By: DrAllis
Date Posted: 17 Jun 2019 at 7:27am
| First failure old age and a loosened up plug. Second failure is from a cheap o-ring. |
Posted By: Joe(TX)
Date Posted: 18 Jun 2019 at 4:10pm
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Did you use a standard o ring or one made for a hydraulic fitting? They ar not the same. ------------- 1970 190XT, 1973 200, 1962 D-19 Diesel, 1979 7010, 1957 WD45, 1950 WD, 1961 D17, Speed Patrol, D14, All crop 66 big bin, 180 diesel, 1970 170 diesel, FP80 forklift. Gleaner A |
Posted By: Play Farmer
Date Posted: 24 Jun 2019 at 9:14am
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Following up on this one - you guys were, as usual, 100% spot on. I picked up the proper "boss O-Ring" at our local hydraulic shop and put it back together. I worked it all day yesterday without an issue. I'll call this one fixed. Thanks for the help. On a side note, a buddy of mine is a hydraulics engineer by trade, he gave a more in-depth description/answer too; The very first thing that came to mind when I looked at the picture was, are you using the correct size o-ring in there? Those fittings require BOSS O-RINGS (See the attached chart and illustration). Standard industrial O-rings (i.e. -100, -200 etc. series’) won’t work well on those fittings. They must be BOSS O-RINGS. BOSS O-RINGS are typically made from 90 durometer Nitrile and therefore more resistant to extrusion, whereas standard everyday industrial Nitrile O-Rings are typically made from 70 durometer material. |
Posted By: DrAllis
Date Posted: 24 Jun 2019 at 9:22am
| Like comparing a grade 5 bolt to a grade 8 bolt. They look alike but they ain't the same...………. |
Posted By: Play Farmer
Date Posted: 24 Jun 2019 at 9:52am
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Yup! When the original came out it was hard and somewhat brittle. In my real job a harder o-ring is a bad deal. I knew brittle was bad, the harder part was something I'm not used to seeing. I'm chalking this one up to "I'm never too old to learn" and "I won't make that mistake again"!
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Posted By: SteveM C/IL
Date Posted: 24 Jun 2019 at 12:55pm
| Boss eh? That's interesting. I recently replaced some o-rings on the pump head of a cheap 7hp pressure washer. Got em at the local welding,hydraulic cyl repair, you name it they fix it shop. He gave me "boss" orings as they were what seemed to fit best. Good choice and maybe by chance. Anyway,doing the job and lesser may have failed. I wrote the part number on the washer. |