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I have a 1985 Ford 1510 tractor with hydraulic problems. I can be running a piece of equipment and everything will be fine and all of a sudden the hydraulics will just lose all pressure. The mower deck or bush hog will simply drop to the ground. After a few hours I can fire it back up and everything will be working ok for another hour or two. I’ve added fluid and there appears to be plenty of fluid on the dip stick. I was told there should be about an inch on it.

I’m new to this kind of experience and have never lived on more than a city lot or two. Now I have over 3 acres to take care of so I purchased this tractor primarily for the mowing.
Thanks and any suggestions in trouble shooting are appreciated!
 

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:MTF_wel2: , William Turner!!

For an implement to suddenly drop to the ground due to losing hydraulic system pressure doesn't compute except for problems with the control valve, or catastrophic failure of a hose or cylinder. Neither of the latter 2 are self correcting, so back to the control valve.

Possible reasons for control valve failure under your stated conditions.

- Accidental bumping of the lever. (Been there, done that!)

- Control valve spool centering spring(s) weak or broken, or o-ring seal requires replacement. (Been there, too!)

- Worn linkage allowing the spool to shift. (Part and parcel with the above springs and seals.)

- System is overheating and needs a cooler or a good exterior cleaning of the transmission, and a fan inspection. (Not normal, but definitely in the running because of the stated conditions.)

I'm not familiar with your tractor so my suggestions are general in nature. Depending on the type of control valve (I only use spool valves and yours may be a different type), disassemble, clean, and inspect for damage. Repair or replace as required.

High temperatures in the system can cause all kinds of headaches, all the way up to failed components. Normal operating temperatures of most hydraulic systems are in the range of 140-160*F, 180* is high, but still acceptable. 200* is not acceptable and must be addressed. Acquire a digital laser infrared temperature gun and check the reservoir (transmission) temperature immediately when this problem occurs.

Good luck, and please report back so that someone can offer specific assistance for your problem, and maybe someone else can benefit from your findings and repair.
 

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I have a 1500, a little older but very simular. I think Tudor is right on the money in reccomending you look into the Control Valve first.
Mine has never dropped unexpectedly. But will bleed off and drop an implement quickly when the engine is shut down. I'm sure I need to pull it apart and change an O ring.
These are great tractors and sure worth finding the problem and fixing.
 

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Discussion Starter #4
Up Date!
Although I haven’t been on here for a while I thought I would share the final problem how it was resolved. I took the tractor to a repair shop and I was told that the hydraulic lines had a lot of air in them. Got it back and it worked fine and once again this happened. I returned it back to the mechanic that worked on it and the plug was loose on the bottom which leaked out the fluid. This was last summer / early fall and everything has been fine since.

However, on another note sometimes it (hydraulic system) will jerk a little (sort of difficult to explain) but when I adjust the hydraulic lever ever so slightly it will quit. It still holds the 3-point up as needed until its shut off then it will bleed off and drop at that point. I’m not too concerned about all this as long as everything works as good as it does right now.

Thanks!
 

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Thanks for letting us know the final outcome!

There should not be any air in the lines if the reservoir is full and there are no leaks in the supply line to the pump. Hydraulic systems are self bleeding, needing only to exercise the cylinders to push air from the lines back to the reservoir.

If the 3PH stays up while the tractor is running and bleeds down over a few hours when parked, that constitutes normal. If it constantly needs to be raised when operating and bleeds down in a few minutes when parked, either the valve is worn, or the cylinder seals need to be replaced. From your description of the 'jerking' and your corrective action, I'd suspect the valve, especially if the 3PH stays up while operating.
 
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