MF40 FEL and BH quit

Paul007

Member
There I was, happily pushing dirt around today when suddenly, and without a sound, the hydraulics quit. Shaft from front of crank to pump is turning, plenty of fluid in the tank. I think I can hear something faintly when I pull the levers, but not a hint of movement upwards.

Do filters plug completely? What's the troubleshooting procedure?

Dang...
 
All I could see last night with a flashlight, in the mud, was the shaft looked to be solidly attached at the engine, couldn't see much of the pump. I did find the troubleshooting section in the manual, under "fails to raise" it says:

A Fluid level - that's OK
B Wrong type if oil - hadn't added any
D Obstruction in pump suction line - Hmm..
E Pump not operating or properly - Check pump drive (coupling, somewhere), flow, relief valve - gulp
H Main relief valve malfunction - wherever that is
T Control valve worn or obstructed - wherever that is

I did notice the FEL stopped working a few days ago but just briefly and worked for several hours since, perhaps related. Also read that the filter has a bypass so even were it plugged it would pass fluid.

Thanks for the reply.
 
your front pump shaft is splined the pump shaft is the male end and the tractor end is the female that is why it looks like it is turning. also you could have broke the pump shaft but i bet it's the spline. some had grease zerks on them
 
Main relief valve is likely in the control valve body. Control valve is
the part control levers are attached to. Perhaps something is stuck
in the relief valve blocking it open, or, it's broken, though I'd think
that would produce an audible sound if it's constantly bypassing
under load. Do you have a pressure gauge you can plumb into the
control vavle? There must be a port for that there somewhere.
 
There would also be a relief valve in the backhoe controls. Not sure,
but I think if either of those is stuck open, they'll relieve the whole
system.
 
Thanks guys. Went back out today armed with a little bit of knowledge. I pulled the out line off at the pump and fired it up. Fluid came out, pulsing, but I could hold my finger over the port indefinitely, no pressure. Next step (he thought) was to check for oil supply to the pump, best I was able to do at the time was get the hose clamp loose and slide a screwdriver between the hose and pipe, and fluid did come out seemingly freely, at least enough that the pump should have built up pressure after a few seconds with my thumb over it.

So maybe it is the drive splines, and it's still spinning the pump a tad. Zerk, what zerk? :oops: Whaddya think? Should I pull the pump as a unit, or pull the front cover off to double check if it's turning or not? Can I just drill a hole through the shaft and put a bolt through it? :)
 
you can not drill a hole in it for a bolt it is harden steel. last two i change i made a new coupler to match the pump because you will not want to pay the price from MF. to find a aftermarket pump is easy but to find the female coupler will be harder. Case 450 crawler loaders and dozers use the same kind of set up
 
If you pull the cover off the pump and fire it up, you'll be in for a
new pump anyway, I would think. May as well pull the whole pump
and check the coupler. If it's fine, and the intake hose isn't
collapsed and she's getting oil, then you'll know it's the pump.
Either way the pump'll have to come off, so may as well go that
route, if the oil supply is not the problem.
 
Thanks again guys. I poked around at some old posts on the forum and it does sound fairly common for the drive to strip, so I guess it's off with the pump. Looks simple (he said wishfully). With the backhoe I guess I got the extra fluid cooler above the pump but it still looks like just the hoses and a couple of bolts. Pouring rain through Christmas and it's outside in the mud but I'll let you know.
 
Got a break in the weather today so I pulled the pump. Can't get it out of the tractor with the cooler above it in place but I was able to turn it around, look at the splines and also peer and poke a finger down the drive shaft. There is about an inch and a quarter of splines on the pump, and a corresponding depth in the hole in the end of the drive shaft. The first third or so of the shaft hole has no splines, it feels like there used to be. It is normally splined all the way to the end, correct? About a corresponding amount of the splines on the pump seemed to be plugged with debris or worn metal. I'm guessing the pump was only engaging the first third of the available spline length. In fact, it looks like if I removed the drive shaft, cut off the part with not splines left and spaced it out from the crank (or lengthened it somehow), I could potentially end up with more spline area engaged than before. What is involved in removing the shaft, just unbolt from the crank? What is there where it passes through the tractor frame, just 40 years of muck?
 

Bump. I have not gone out to remove the hydraulic pump drive shaft from the crank. I have to haul my tools out there so I am wondering, do I just undo the flange from the crank and slide it forward (the pump is off) and then tilt it out the side, or do I have to unscrew the shaft from the flange (reverse thread I understand) before I can get the shaft out of the tractor?
 

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