my latest project tractor: a 2003 McCormick GX50H

[ultrarunner]

I admired your tenaciousness... if anyone can get this sorted out you're the one.

 

[dfkrug]

Thanks, UR, I will try to keep it interesting.

Just got back from vaca, and here I will show the splitting operation. This is maybe
my 4th or 5th split, and I usually do that outside, supporting one side with my
loader. This part is much easier and less precise than the reassembly. For
that I do it in my workshop using my electric overhead trolley-hoist.

I decided to split at #2 point, despite the manual saying to do it at #1. The
bolts/nuts were a bit easier to get at, and it has never been split at #1.
After-the-fact, I can see that #1 is better cuz there is only one spline
shaft engagement, and the HST is less exposed to possible damage. At
split point #2, both the PTO shaft and the HST output shaft need to be
engaged, which makes reassembly harder.

On to the split. First the MFWD drive shaft gets removed. This is the same
as all 4x4 tractors I have had in that there are two spline couplers with
roll pins. Drive these out and slide back the couplers, and it comes out.

Moving the front section of the tractor around requires putting wedges
on both sides of the tilt axle.

 

[dfkrug]

Now here is the inside of the aft end after the split. The 2 splined couplers (PTO and
HST output) need to be aligned simultaneously during assembly.

 

[dfkrug]

An initial external inspection of the HST.

Things I noticed: rubber-coated pressure lines to the swash plate servo cylinder
seem to be deteriorating. These hoses are bathed in ATF all the time. When I
removed them to check the lines, the coating crumbled in my hands. Who
decided to use these hoses?

Also, look at the arrow in the second photo. The hardline seems to have taken
an impact here. Sealant seems to be on unexpected surfaces, too.

Otherwise, things look OK.

 

[dfkrug]

The next steps involve removal of all the pressure lines, checking for blockages,
then disassembling the HST. I used air to blow out the lines, and to deduce
the function of pathways in the castings.

In removing one of the larger hardlines, I found my culprit. The impact on the
hardline broke it at the fitting. I am certain this happened when a previous
mechanic was splitting or reattaching the tractor. This is the other reason
the tractor should not be split at this position.

 

[ultrarunner]

Great sleuthing work...

I could only imagine the cost to do what you are doing would be prohibitive having it done.

 

[dfkrug]

I could only imagine the cost to do what you are doing would be prohibitive having it done.

It is hard to imagine an established tractor shop, dealer or not, asking less than $2K for a job
that requires splitting the tractor. Even more if it is industrial with an additional "mainframe" and
FOPS.

I have a copy of an invoice here for about $9700 to "fix" this tractor a couple of years ago. The
owner at that time did not get a working machine, it appears, based on the hour meter, and
got rid of it. That work was performed by a dealer. The current owner picked this unit up
non-op with the hope of fixing it.

The collateral damage caused by these "repairs" is evident in not just the broken hardline, but
the complicated electrical system with over a dozen relays has been ravaged by cut and
frayed wires, and disconnected circuits. The electrical info in the manual is disgracefully
bad, so I have had to trace circuits manually and bypass numerous relays.

 

[dfkrug]

Here is the good news:

The HST internals look good. No signs of excessive wear in the charge pump or the
valve plates of the motor or pump. Piston shoes all look good, too.

No parts breakdown forthcoming from the dealer I have contacted, tho there is a
part # for a parts manual. He can not give me any info, he says, on the internals
of the HST. He says the manufacturer requires total HST replacement if there
is a problem. I hate to say this, but that is a reason not to consider this brand.

 

[dfkrug]

Here is the servo controller mechanism for the swash plate control. The cylinder is
double-ended and pushes/pulls on the lever arm to rotate the swash plate. If
you look closely, you can see that the arm pivots in a saddle that looks very
similar to a crank bearing insert on an engine. It even has a coating, not visible
in the photo. This seems to be a replaceable wear item and this one is somewhat
worn, but servicable.

I would replace it as a matter of course in this inspection, but no parts are available!

 

[dfkrug]

Fans of HSTs might have noticed that I did not talk about inlet filtration. That WAS a big
concern I had earlier, given the failed pump. The inlet filter is not just a metal mesh, and
that is problematic. If resistive to flow, then cavitation of the HST pump could destroy it.
I have seen some pretty clogged inlet screens on Deeres.

The inlet filter is over 9" long, and is a stainless screen over a fibrous filter medium. Since
it is hard to see inside, I cut it open to see if it was a problem, and knowing it would be
replaced. I also cut open the filter material (not shown). It was not the problem.

This was done before I cracked the tractor.