Melted Hydraulic Filler Cap

   / Melted Hydraulic Filler Cap #1  

reebree

New member
Joined
Oct 17, 2009
Messages
3
My hydraulic/transmission oil got so hot it melted the filler cap on My Kubota M9540, what is wrong?
 
   / Melted Hydraulic Filler Cap #2  
Just how hard were you working the tractor? Are the hyd level OK? Do you have a fan on you transmission, and is it working . Do you have a relief valve that is working more than usual? Do you have a hyd radiator up front, and is it clean. Did the engine coolant heat up also? Smell the fluid and if you detect a burnt smell, might be time to change the fluid and find the cause.
 
   / Melted Hydraulic Filler Cap #3  
Sounds like the system has spent a great deal of time running over the relief valve. Not good for open center systems. You need to find out what the cause is, or you'll be replacing more than the fill cap.
 
   / Melted Hydraulic Filler Cap
  • Thread Starter
#4  
The radiator and screens were clean and tractor engine running normal temp.
I changed the hydraulic oil and filters. I was cutting hay with a 10' Vermeer trailmower which does work the tractor pretty hard. The fluid has gotten warm before but never melted the fill cap. After changing oil and filters I tried it again in the hay field, the cap did not melt but the housings and remote outlets got so hot I could not leave my hand on them. I am not sure what the normal operating temp of the oil should be, I have been told that 100 degrees above ambient is normal. If that is true, then you couldn't ever leave your hand on the metal. 70 degree anbient would equal 170 oil temp.
It also got hot with out the mower even attached to tractor.
 
   / Melted Hydraulic Filler Cap #5  
Sounds like you are dead heading your hydraulics putting it into relief. Are you using a detented remote for a lift or angle function on the mower?
 
   / Melted Hydraulic Filler Cap #6  
The radiator and screens were clean and tractor engine running normal temp.
I changed the hydraulic oil and filters. I was cutting hay with a 10' Vermeer trailmower which does work the tractor pretty hard. The fluid has gotten warm before but never melted the fill cap. After changing oil and filters I tried it again in the hay field, the cap did not melt but the housings and remote outlets got so hot I could not leave my hand on them. I am not sure what the normal operating temp of the oil should be, I have been told that 100 degrees above ambient is normal. If that is true, then you couldn't ever leave your hand on the metal. 70 degree anbient would equal 170 oil temp.
It also got hot with out the mower even attached to tractor.

You are correct about the expected temperatures, but that would not melt anything!

As others have suggested, somewhere there is a valve that's not centering, or another sever restriction in the system.
 
   / Melted Hydraulic Filler Cap #7  
My hydraulic/transmission oil got so hot it melted the filler cap on My Kubota M9540, what is wrong?

If you add some test ports in your hyd circuits, and make up and use a hyd test gage and hose with QD's, you can detect any pressure in the system and analyze the results.

For instance, If a valve were not centered, the fluid would flow to a cylinder, like the 3pt, and with the 3pt up, you would not know that the relief has opened with out the gage connected. . In a normal situation, with all valves in neutral, there should be no or very little pressure in the system. When a cylinder is operating or a hyd motor is running, then you would expect to see some pressure on the gage.

Now if you have a hydrostatic transmission, and you are working it hard, expect the fluid to get hot. Some of them have a flushing valve to send fluid through the hydro case, and route it to the hydro radiator, and back to the reservoir.

You need to keep the heat under control, around 185 to 200 degrees. You may want to consider a separate radiator with fan to assist in cooling the fluid. Melted filler cap is not a good thing.
 
   / Melted Hydraulic Filler Cap
  • Thread Starter
#8  
First, I want to thank yall for the help. The tractor does have a hydrostatic transmission. I started it today and felt of all lines to FEL, 3pt, and remotes, nothing got hot ahead of the whole system, the first thing to get warm was the pump. I made two rounds around a five acre field with the above mentioned mower and the oil was at 220 degrees, I shut it down until tomorrow morning when dealer will be open.
 
   / Melted Hydraulic Filler Cap #9  
Where you able to determine your hydraulic issue?
 
   / Melted Hydraulic Filler Cap #10  
IF it heating up from just continual use and there is no valving issues, you may want o consider a oil cooler and a fan to circulate air through it....
 

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