180 hydraulic main relief valve
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=184433
Printed Date: 18 May 2025 at 2:36pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 180 hydraulic main relief valve
Posted By: ksbowman
Subject: 180 hydraulic main relief valve
Date Posted: 06 Nov 2021 at 4:37pm
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Checked my Hydraulic pressure today at an auxiliary port and the pressure would go up to 1300 @ 2,000 rpm then drop to 1000. It would repeat this over and over so I assume the valve was popping out at that pressure. Tomorrow I'm going to adjust it as it should read 2,300. Is this much under pressure an indication the pump has worn bad or do the valves go out of adjustment that much thru use?
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Replies:
Posted By: DrAllis
Date Posted: 06 Nov 2021 at 4:43pm
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The seals inside the valve fail with age. You'll screw around trying to adjust and probably get nowhere. Then, if you take it apart to reseal it, the adjustment will be too high from messing with it earlier and you could split the pump wide open from too high of pressure setting. Any one I ever resealed, I never once had to change the adjustment....it was pretty much right where it belonged.
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Posted By: SteveM C/IL
Date Posted: 06 Nov 2021 at 7:53pm
Posted By: rw
Date Posted: 06 Nov 2021 at 9:21pm
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yep on splitting the pump also.rw
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Posted By: ksbowman
Date Posted: 08 Nov 2021 at 5:23pm
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Rebuilt the main hydraulic valve today and the pressure holds a steady 1400#. May tke it back out and go thru it again. If the pressure doesn't change for the better I'll try readjusting it.
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Posted By: DrAllis
Date Posted: 08 Nov 2021 at 5:33pm
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Did you find any blown Orings or back-up rings ???
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Posted By: ksbowman
Date Posted: 08 Nov 2021 at 6:48pm
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No back up rings looked bad but the o- rings especially the one on the piston looked tired. I'll disassemble and really look closer at the back up rings. It amazed me how easy it was to get out and take apart on the bench. I had the shop manual out and the total it showed was 4 o- rings including the outers. That was how many I replaced was 4. Was careful to keep everything clean too.
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