Fixing the John Deere...Again

[Qweaver]

400 hours--the computer went bad.  $2700 parts and labor.  1200 hours the main hydraulic pump quit.  It took 4 hours to pull the front of the tractor apart to get to the pump.  The problem is that the splined coupling connecting the pump to the engine stripped.  The pump turns freely and the splines look fine.  I'll pull the pump apart just to make sure it is OK.  Easy enough to buy a new coupling (the local JD did not have it in stock) and put it all back together...but something caused that spline to strip.  If the pump looks good and it does turn freely...what do I look at?  Something caused those splines to strip!!   

Tired of fixing things!
Quinton

[Brian_Rhoad]

If the bolts that hold the coupler on the shaft are loose the coupler will wear.

[Qweaver]

Not loose

[sandhills]

Personally I wouldn't take the pump apart, if it turns freely get the new coupler, it's a pain but way cheaper than a new pump.  If it in fact does turn freely I'm with Brian, problem was with the coupler, I tried telling dad a few years ago not to buy a new hyd. pump for his 4010 JD but he did and when I tore it apart the coupler was bad on one end, he still put a new pump in it  : = expensive!

[POC]

I've made COUNTLESS repairs to my Mahindra TLB, it has about 220 hrs.  Not a fan so far.

I hate buying something new and having it tear up all the time.

[DeepCreek]

I would make darn sure there wasn't a hydraulic lock before calling it fixed.

[Qweaver]

I would make darn sure there wasn't a hydraulic lock before calling it fixed.

I agree, how do I do that?  What could lock it?

[Qweaver]

I hate buying something new and having it tear up all the time.

My sentiments exactly! 

[DeepCreek]

Stuck or blocked pressure relief is where I would start.

[Qweaver]

I'm looking thru the manual and so far can not see where pressure relief happens.  This hydraulic system is not simple.

[Dave Shepard]

Rust is taking out the splines. I'll explain later. On stoopid phone now.

[coxy]

its a jd they are good for that  in the 440 skidders anyway   ;D

[Corley5]

Yup on the rust taking out the splines    Rust is abrasive.  Put a coat of water resistant grease or anti seize on the surfaces when you put it back together.   

[Qweaver]

Rust is taking out the splines. I'll explain later. On stoopid phone now.

No indications of any rust.

[Corley5]

I had a similar set up on an Iron Mule.  Rust was an issue but there was also an alignment problem.  After the 2nd failure I put in a Love Joy coupling.  That solved it ;) ;D

[Brian_Rhoad]

When I say tight bolts I meant the bolts were tight and squeezed the coupler tight onto the shaft. Not that the bolts them selves were tight. I have a JD 440 skidder that wore out the splines because the coupler wasn't tight on the shaft.

[Dave Shepard]

The rust issue with splines is an age old one, as well as microscopic. At rest, a thin layer of rust forms on the splines. When you turn the pump, it wears away this rust, only to have it form again the next time the machine sits. This is very common with PTO systems on big trucks. I think Chelsea, the PTO manufacturer may even have a special grease for this application. I am on my third coupling for my Kubota L48. My pump has a casting bolted to the front of it that holds two bearings, and in those bearings is the splined coupler. The alignment is perfect. About two years ago I was working around the mill yard, and picked up some big ugly piece of junk with a little too much gusto. It stripped out the coupling, which of course was eroded to almost clearance dimensions by this time. I bought a new coupling and bearings, and assembled with some really heavy grease a friend recommended. The pump splines were also compromised in width, but not in diameter. Last fall, maybe 150 hours later, it stripped again. I got another coupling, and used RTV between the bearing housing and the pump, filled the inside of the bearing housing with heavy grease, and put RTV around the outside of the coupling where the end of the pump shaft is. I've gone probably 200 hours now. I do fear another issue, as the pump splines are compromised, but there is nothing to do but wait it out, a pump is about $700, plus another coupling for $70.

[Qweaver]

Thanks for the input everyone.  I hate to put a new coupler on without being absolutely sure what caused it to strip. 

[snowstorm]

I'm looking thru the manual and so far can not see where pressure relief happens.  This hydraulic system is not simple.

if it has a piston pump closed center system then it re leaves at the pump. thats why you dont see a releif valve

[Qweaver]

It's not piston, it's gears.

[Dave Shepard]

If you had a catastrophic failure, then the splines wouldn't likely strip, too much area. You would break something between the pump and crankshaft. I don't know how yours is coupled, but my Kubota has a short shaft with two bolt flanges, sort of like a rag joint on old steering systems. Those two bolts would surely break before the splines would break off. Have you looked closely enough to determine if there was actual breakage, or was it just wear?

[Qweaver]

The splines on the pump are hard.  The splines on the coupling are softer on purpose so that if a failure occurs it's in the less expensive part.  I spoke at length with the service manager at a large JD dealer and he said that this just fits into that "stuff happens" category  and that it is a common repair for him.  He also said that it has happened to their JD skid steer  three times.  I swear that is exactly what he said.   The part with shipping and tax is $80.  As usual, a ridicules price and an unacceptable failure  for "no" reason.  There has to be a reason!  Four hours to get it apart and at least four hours to put it back together.  I love how this TLB works but I will never buy JD again.

[DeepCreek]

So, an $80 part and eight hours of labor are simply due to a wear item, and JD's response is  smiley_nananana.

Note background color of that smiley.   :D

[thecfarm]

I really think they fixed that problem with the next model changeover. Or they should of. Probably some great engineer idea that did not work out the way he wanted it too. Probably saved JD $80 on each tractor made.  :D

[Dave Shepard]

I don't think there is a next model on that one, it was just discontinued.