AgcoAllis 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=39570
Printed Date: 25 Aug 2025 at 12:05am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: AgcoAllis hydraulic problem
Posted By: JimF
Subject: AgcoAllis hydraulic problem
Date Posted: 26 Oct 2011 at 5:41pm
| I have a 1993 Agco Allis 6690. Sometimes when operating the tractor, the power steering will quit and I can't raise the 3-point; however, the front loader will work perfectly. I can shut off the tractor and come back later and everthing works fine for a while. At other times I can start it 2 or 3 times and I have no power steering. Also, while operating it, it will lose the power steering and 3-point. Help! What can I try? |
Replies:
Posted By: Pat SW Ohio
Date Posted: 26 Oct 2011 at 6:45pm
| I have a '95 6690 and had very similiar problems. Transmission,hydraulics and power steering use same oil reservoir. Bleed the hydraulic system by loosening fitting at steering cylinder and operate steering wheel back and forth to get any air bubbles out ands then tighten. After that check oil level and fill to sight glass on rear of tractor. Also make sure ALL hydraulic lines and fittings are tight. Hope this helps. |
Posted By: JimF
Date Posted: 26 Oct 2011 at 7:26pm
| Thanks for the information. I will give it a try tomorrow! |
Posted By: JimF
Date Posted: 28 Oct 2011 at 2:37pm
| Thanks, Pat, for the suggestion. Tried it today, but it didn't work on this one. Does anybody else have an idea? |
Posted By: hoffmanfarms
Date Posted: 28 Mar 2019 at 12:22am
I know it has been 8 years, but what was the solution to this problem? My 6690 started doing this for the past couple of weeks. Finally today the inside wall of the left side rear tire was covered in oil, and oil was running down behind the fuel tank near the hydraulic filters. Something finally broke, not sure what though. But this description is exactly what was happening to us. (And our 6680 is in the shop.... can’t figure out why I keep running these guys...) 
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Posted By: DaveH
Date Posted: 22 Jun 2019 at 12:31pm
| Same here. I've got a '95 6690 with same issue. I've been told it might be O rings goint into the hydraulic pump, but have not had a chance to check it out yet. Any advice would be welcome. |
Posted By: hoffmanfarms
Date Posted: 22 Jun 2019 at 1:05pm
|
Yes, our 1995 6690, when using the hydraulics, it leaks around the pump. After a while the power steering stops working. The sight glass still shows full. If you turn it off and let it sit, power steering comes back. Your point on the O rings actually makes sense, I just wish the pump were in a easier place to get too. |
Posted By: Ryan Renko
Date Posted: 22 Jun 2019 at 9:01pm
| Oh great. Now we have more future issues to worry about with ours!! I wish I would have been more involved in this tractors purchase with my late father. We wouldn't have bought it. Ryan |
Posted By: DaveH
Date Posted: 29 Jun 2019 at 6:45pm
| What I have found is that the 6690 seems to be sensitive to low hydraulic fluid levels. I've (I think) solved my problem by making sure the hydraulic sump is full. I've never had any luck in seeing the fluid in the sight glass, so what I do is to remove the sight glass and fill the sump until the hydraulic fluid runs out of the sight glass hole. Another thing to check is to make sure the hydraulic lever closest to the seat return to the neutral position -- if left in either detent position the hydraulics will freeze up after awhile. Similarly if you try to run with the front end loader fully raised. I think what happens in each of these conditions is that the hydraulic sump is depleted of fluid, the fluid cavitates in the pump, which causes the pump to lose prime and lock up. So, to summarize, (1) keep the hydraulic sump level to the point the fluid flows out of the hole where the sight glass is located, (2) make sure the hydraulic lever closest to the seat returns to the neutral position, and (3) don't run with hydraulic rams fully extended. |
Posted By: Ryan Renko
Date Posted: 29 Jun 2019 at 9:34pm
| I have always had a hard time seeing that sight glass also. Several times I found a small hill and parked the tractor with the front downhill so I wouldn't lose any fluid and unscrewed it and wiped it off to remove any film. Also using a light helps atleast with my eyes. Ryan |
Posted By: DaveH
Date Posted: 01 Jul 2019 at 10:15pm
| One other thing to check if oil is leaking around the oil filter. Make sure that when you removed the old oil filter, the sealing gasket from the old filter was not inadvertantly left on the engine. Then, when installing the new filter, you end up having two gaskets. I've never done this on a tractor, but did once on a car. |
Posted By: tbran
Date Posted: 03 Jul 2019 at 10:29am
|
We sold about a hundred of these, after time the large rubber seals on the system leak - and suck air. One solution - remove the LH wheel and reseal about 10 items - 72230620 find that part on agcopartsbooks.com and order those oring seals 72230623 support gaskets and orings and replace those and you will be healed - loosen the power steering hose to bleed both pumps. .. ------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: JohnCO
Date Posted: 04 Jul 2019 at 12:03am
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Derrick, did you get your problem solved? I don't think we have met but probably walked by each other at an auction or the farm show. ------------- "If at first you don't succeed, get a bigger hammer" Allis Express participant |