MTZ Tractor Talk

Main MTZ Talk => Maintenance - Service & Repair => Topic started by: sd825 on March 27, 2019, 01:38:25 PM

Title: 825 steering issue
Post by: sd825 on March 27, 2019, 01:38:25 PM
Hello! I had a problem develop with the steering in my 825 a couple of days ago. When I was feeding cows, it became extremely difficult to turn to the left. The steering fluid was very low, so before I fed yesterday I filled it up (approx. 4 qts). Everything was working fine for about half an hour, and then the left turn problem started again. It still turns to the right, and turns back to straight, but will baaaarely turn left, and it requires a lot of force on the wheel to get it to turn even the smallest amount. This morning I went to clean a bit of snow out of the driveway. The fluid reservoir was still full, and everything worked fine. I was only running it for 20-30 minutes, but when I was about done I noticed the steering getting tough again. This problem seems to only happen after I've been running the tractor for 20-30 minutes or so, so it seems to be somehow temperature related. Any ideas on things I should check or likely problems?

Some things that occur to me: 1) could the low fluid level have damaged the pump? 2) Is there a leak developing in the steering hydraulic cylinder that doesn't let it retract all the way (for a left turn, cylinder extends for a right turn). I don't know that a damaged pump would be temperature dependent. I would greatly appreciate any other ideas or suggestions for things to look at!
Additional info: I got stuck in a deep, hard snowdrift in my driveway last week. The county pulled me out with a road grader, but it was still through a lot of packed snow, and was kind of a rough pull - is there something that could have been damaged during this I should look at? I was also trying to use the differential lock when I got stuck (not sure if it works or not), and I think that is somehow connected to the power steering unit? I have used the tractor a few times since then before this issue developed so I don't think that is the problem. I'm kind of at a loss here, and need to get my tractor going soon to keep the cows fed!! I don't want to keep running it with a problem and cause any further damage. Thanks so much for any input!!
Title: Re: 825 steering issue
Post by: Haymaker on March 28, 2019, 12:26:31 PM
Yeah the diff lock I believe is applied using the power steering system.  There is a line running down on the left side to the rear brake area.  There are o rings in that that leak.  Guys pull line the line off and cap it so you don't lose your power steering oil. 

Maybe lift the front end up using your loader and turn the wheels side to side insuring nothing is bent binding etc.
Yes if it was running and had none to little oil in the power steering system you could have done damage to the pump for sure. Warn hyd. pumps show up when the oil is good and hot vs. cold and thick.

I suppose you could T in a gauge and check the pressures down on the steering cylinder. That's what i'd do to see what's going on if nothing is binding etc. If the steering cylinder say had a damaged seal you think you would notice it both ways.  Also of course the little cylinder will have more force one way vs the other due to the design with the rod displacing surface area on one side of the piston.  Not sure if that's enough of a difference but it sure makes a difference on say a loader cylinder and if your power steering pump pressure is low then you'd notice it I imagine. Those power steering pumps are pretty cheap I believe it that turns out to the issue.

Title: Re: 825 steering issue
Post by: sd825 on March 28, 2019, 02:07:16 PM
Thanks a lot Haymaker! I picked up some Lucas Oil hydraulic conditioner/stop leak today to try out. I was thinking I might have a seal in the cylinder going bad allowing fluid to bypass. I'm hoping for a simple fix, but it might not be so easy! If that doesn't change anything I'll start checking out the pump. Could I just plumb both of the cylinder lines directly into a pressure gauge (just removing the lines from cylinder vs teeing the gauge into the line), or would it need to actually be in line with the cylinder in place?

 I jacked it up with the loader last night and it will turn both directions, but I can still feel a bit of sticking going to the left. Obviously it requires a lot less force up in the air vs. with a tractor+bale on it, but it doesn't look like anything is bent or binding. I think my oil leak may have been caused by trying to use the diff lock, as I check the level pretty regularly and have never had any major disappearance of oil like this.
Thanks again for your thoughts!
Title: Re: 825 steering issue
Post by: Haymaker on March 28, 2019, 02:56:05 PM
If there is no leaks at the front and you check it regularly then i'd take a look at the diff lock system.
I'd have to look in the book to see what the pressure should be on that little PS pump.  Not sure what fittings are used it maybe expensive to plumb something in to take pressures if you have to build a hose with bango fittings etc.  Think that pump is like $150 only.
Title: Re: 825 steering issue
Post by: sd825 on June 24, 2019, 02:43:26 PM
Well it's a bit late but wanted to follow up on this in case it can help someone else someday. I replaced the power steering pump and that was indeed the problem. $150 bucks and a pretty quick and easy job, and I had a functioning tractor again (the day before a 2 ft blizzard blew in, thank goodness that part showed up!). One of the rubber lines running from the power steering unit to the diff lock was split and dumped all the steering oil when I tried to engage the diff lock. That was probably the source of my slow leak, but it was a full on gusher when I tried to use the diff lock. Thanks for the help!