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Discussion Starter #1
Hi,I am new to this forum but avid fan of John Deere tractors.I have a 1952 mt that is in restoration progress.I have it running fine and the lift worked great until I blew a rusted pressure line
in the pedestal.The previous owner had replaced it at some point in time with a 3/8 flex line and it worked fine until it blew the rusted line.I replaced the line with a 1/2 inch line and now it will not work at all.I am going to check the pressures but I can hear fluid bypassing inside the lift housing.Did the increase in volume cause the pressure to increase or is it a chance that the relief valve is stuck open???
 

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Wish I could help but I'm sure someone should be able.

Welcome from West Virginia

:wgtt:
 

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This may be a stupid question, but is there enough fluid in the reservoir? Other stupid question, but is the right stuff in the system? The touch-o-matic takes straight 10w motor oil or ISO 32 spec light hydraulic fluid.

I would start by firing up the tractor and cracking open the high pressure line at one of the compression fittings between the pump and the touch-o-matic in order to rule out a damaged or weak pump. The pump may have been damaged when it ran dry after blowing the line because it relies on the fluid moving through it for lubrication. One of the shortcomings of this particular design is that there is no way to disconnect the pump; if the tractor is running, it is also running.

The real trick to diagnosing a fault in a hydraulic system is to rule out as many components as possible before tearing into anything. Once the pump has been determined to be moving fluid, the problem must be somewhere else. The bad news is that I don't know a lot about the internal workings of the touch-o-matic unit itself. The good news is that it is a fairly simple device and shouldn't be too difficult to figure out once you get it off the machine and onto a workbench.
 

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Discussion Starter #4
mt lift

thanks for ith info,the pump is putting out pressure ,I cracked the pressure line going into the lift housing and it has good pressure.I am going to put a pressure gauge on it maybe tomorrow and check the relief valve settings.I can hear fluid moving inside the lift piston area and also took fill cap off and the fluid is not churning.I serviced with 10 wt motor oil.I have read up on the relief valve settings in the service manual and looks like that may be the problem.It will lift itself up with no attachments but any weight on lift arms and it just will not lift.I don,t know if the previous owner had to adjust the relief valves going to a 3/8 line when he replaced it. Thanks for the replies,Tim
 

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Discussion Starter #5
success

I verified pressures with the direct reading gauge and no pressure at the valve housing but pressure from the pump.Got out the john deere service manual and pulled out the 2 relief valves one at a time,found rusty crud from the blown line blocking relief valves and the pressure bypass valves.cleaned up with cleaner then pulled the check valves and shuttle valve and cleaned :laugh:.Removed the front cover and cleaned out,replaced with new gasket.reassembled the rest and serviced.Pressure came up to 500 lbs.Now to remove the rockshaft one more time for another pressure adjustment and it should be good. The john deere service manual is spot on how to rebuild these units and you can do it all bolted to the tractor.Hope this helps someone else. Ready for spring plowing!
 

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Nice to hear you got it sorted out!

Now you've got me wondering about how much crud is built up in mine...
 

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Discussion Starter #7
mt lift

Yes but if you have a john deere service manual it gives details how to flush the system. Basically just drain fluid and replace with kerosene,run the tractor and run the lift thru several cycles,shut off,drain kerosene then engage starter without ignition on and pump lines free of kerosene then reservice with oil. I had the crud from the rusty line that ruptured in mine. Tim
 
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