Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Mtd 990 Hydraulic Lift


  • Please log in to reply
9 replies to this topic

#1 Franky OFFLINE  

Franky
  • Member
  • Member No: 44612
  • 9 Thanks
  • 6 posts
  • Location: South Carolina

Posted September 03, 2013 - 12:31 PM

Hello all . New here, first post and question. I posted this on another forum without much response, so I figured I would post here also. I recently picked up a 1974 mtd 990 in rough shape and got it running good enough to drive it around and check everything out. Forward and reverse  work well in both hi and lo range, but the hydraulic  cylinder for the lift will only extend and not retract. I can hear a whining noise coming from the control valve when I engage the lift control lever to retract the lift cylinder. The cylinder tries to retract about an inch as long as I keep pressure on the lift control lever. It sounds almost like the fluid is trying to backflow, but has no where to go. Is there a reverse valve on the control valve? Has anyone rebuilt one of these control valves? Any other suggestions? Thanks. 


  • Dieselcubmike and Sawdust have said thanks

#2 boyscout862 ONLINE  

boyscout862
  • Senior Member
  • Member No: 8923
  • 9,803 Thanks
  • 7,543 posts
  • Location: N.E. Connecticut

Posted September 03, 2013 - 01:17 PM

Welcome to GTT. Someone who has the answer will be by in a while. Mean time, check the hydraulic fluid. You can download 3 manuals per day from our Manuals Section. Good Luck, Rick



#3 Dieselcubmike OFFLINE  

Dieselcubmike
  • Senior Member
  • Member No: 11127
  • 1,327 Thanks
  • 1,511 posts
  • Location: Southwestern,Pa

Posted September 03, 2013 - 01:53 PM

Hello and welcome :wave:



#4 Franky OFFLINE  

Franky
  • Member
  • Member No: 44612
  • 9 Thanks
  • 6 posts
  • Location: South Carolina

Posted September 03, 2013 - 01:55 PM

Thanks, I had to replace a leaking hose, so I checked the fluid when I did that and it was right where it needed to be. I hope it's something simple like that, but it usually doesn't happen that way. 



#5 Bob IN OFFLINE  

Bob IN
  • Senior Member
  • Contributor
  • Member No: 24042
  • 1,473 Thanks
  • 676 posts
  • Location: Albion IN

Posted September 03, 2013 - 03:42 PM

It sounds like you might have air in your system.



#6 JDBrian OFFLINE  

JDBrian

    Super Moderator

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2507
  • 9,574 Thanks
  • 14,136 posts
  • Location: Hubley, Nova Scotia - Canada

Posted September 04, 2013 - 06:40 AM

Welcome to GTTalk. A few ideas on the cylinder problem. - Can you verify that the linkage the cylinder moves is free and not jammed? If you can help the cylinder retract by putting some weight on it will it retract? Is the valve actuating linkage working properly and pushing the valve all the way into the retract position. If it seems sticky you could try lubing the valve actuator and linkage. If you do want to take apart the valve try to find a diagram first. It's always harder to put one back together than it is to take it apart. 


  • boyscout862 said thank you

#7 Canawler OFFLINE  

Canawler

    Member

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 1273
  • 1,893 Thanks
  • 1,750 posts
  • Location: York, PA

Posted September 04, 2013 - 07:56 AM

Another common problem to look for on these.  The lever that controls cylinder movement pivots in an extension of the bracket that mounts the lift valve.  That section of bracket is know to crack and break off causing the exact problem you're seeing.  You move the lever but the whole pivot point moves and doesn't actuate the valve fully.


  • TheFarm2004, Alc, boyscout862 and 1 other said thanks

#8 Franky OFFLINE  

Franky
  • Member
  • Member No: 44612
  • 9 Thanks
  • 6 posts
  • Location: South Carolina

Posted September 04, 2013 - 07:44 PM

I think that with Canawler's suggestion and a suggestion from a member on another forum that I also posted this question to we may have this problem figured out. The bracket that Canawler mentioned is indeed cracked. Also going off a suggestion from another forum, I checked the new hose which turned out to be bad. I could not even pass a piece of .035" welding wire through it. The hose looks like the fittings were over crimped when I had it made, so I'll be taking it back for a replacement. I'm going to weld the crack in the bracket and replace the hose again, so hopefully that will take care of my hydraulic problems. I'll give an update as soon as I make the repairs, Thanks. 


  • Alc, Texas Deere and Horse, Dieselcubmike and 1 other said thanks

#9 Franky OFFLINE  

Franky
  • Member
  • Member No: 44612
  • 9 Thanks
  • 6 posts
  • Location: South Carolina

Posted September 11, 2013 - 07:26 PM

Finally got around to welding the bracket and replacing the hose so all is good now. The hydraulics work as they should and seem very strong. Now I'll be moving on to the Briggs engine and already have a couple questions on that so I'll start a new thread later. Thanks for the help.
  • Texas Deere and Horse and Sawdust have said thanks

#10 Canawler OFFLINE  

Canawler

    Member

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 1273
  • 1,893 Thanks
  • 1,750 posts
  • Location: York, PA

Posted September 11, 2013 - 09:45 PM

It's good to hear you got it working.






Top