3-Point Hitch MF245 3 pt lift problem

[halwest]

Hi All. New to this site . My MF 245 Orchard with 2 aux remotes has learned a new trick with the rear lift. It's a 1979 I purchased used. Tractor has been serviced with all fluids and filters replaced and strainers cleaned. Recently the rear lift will only work at low RPM (500). If the RPMs are increased the lift arms will lower. Reducing RPMs will cause them to raise again. As the tractor warms up the problem gradually disappears and the lift will work at normal operating range (1800 - 2250 RPM).
The auxiliary system is unaffected by this . With an implement attached (5' finish mower) and in the raised position the lift will stay in the raised position when the engine is shut off. Based on the lift cover casting# the hydraulic system does not have a dash pot. Not sure how to tell if it is pressure controlled. I have both the operator's and maintenance manuals. Any advice / thoughts greatly appreciated.

 

[Phillip w]

Well here is my thoughts. It almost acts low on hydraulic fluid. I know you said you changed the filter and fluids. You may have " had it full" only to start the tractor, circulate and replenish the fluid, and now you are a little low. I would double check the fluid. The fact that it will hold a load with the tractor off to me indicate the valve body should be ok. The next question is: did this problem just start or is it something that has been brewing. You could be getting a weak pump. That fact that it performs better when it warms up and is revved up tends to point to low fluid or weak pump. Both problems act similar. The low fluid is the cheapest and easiest fix. Hydraulic pumps are petty pricey. I am no expert, but that is my thoughts. Hope this helps.

 

[halwest]

Well here is my thoughts. It almost acts low on hydraulic fluid. I know you said you changed the filter and fluids. You may have " had it full" only to start the tractor, circulate and replenish the fluid, and now you are a little low. I would double check the fluid. The fact that it will hold a load with the tractor off to me indicate the valve body should be ok. The next question is: did this problem just start or is it something that has been brewing. You could be getting a weak pump. That fact that it performs better when it warms up and is revved up tends to point to low fluid or weak pump. Both problems act similar. The low fluid is the cheapest and easiest fix. Hydraulic pumps are petty pricey. I am no expert, but that is my thoughts. Hope this helps.

Thanks for your response. I checked the fluid level and it is at the full mark. I should have clarified that when it warms up it works through the full RPM range.

 

[Phillip w]

How long have you had this tractor? Are the hydraulics slow? The reason I ask is some of these older tractors were pretty slow. If you revved them up they might be a little fast, but still slow. I have a newer massey ferguson and the hydraulics are pretty quick. The loader is maxed at say 800-1000 lbs. I have an older allis Chalmers from the 70's era. She is slow and I mean slow. However she is like Hercules, a real brute. She'll lift a ton literally. I have use the loader as a Jack to raise the front of my pickup. A couple years ago we scrapped a couple old combines. The whole back end of the allis Chalmers came off the growing trying to raise the front of the combine. She is slow, but she is mighty. Hydraulic cylinders are about 3 1/2 to 4 in in diameter. If your tractor is slow, it could be the era of the tractor and the nature of the beast. Other than that I am about stumped.

 

[halwest]

Problem solved! Drained the hydraulic oil and removed the strainer which was clogged again even though there was less than 30 hours since last oil change / strainer cleaning. Figure when the oil was cold the pump couldn't get enough through the strainer and the pump would cavitate / lose suction when the RPMs were increased allowing the lift arms to drop. As the oil warmed up and thinned out a bit enough could get through the strainer to operate the lift. Thoroughly cleaning the strainer and putting in new oil solved the problem and everything is working as it should. Thanks for everyone's thoughts and suggestions!