How to bleed T2220 HST system?

[The Haymaker]

The tee goes up to the pump. I pulled the top of it from the pump, no oil from the line or the pump.

The horizontal (bottom) goes from filter housing over axle to the other two pumps.

The top of the tee is lower than the reservoir, which makes it odd that no oil comes from it, as the other pumps work.

 

[oldnslo]

Then everything points to the charge pump not pumping. Can you access the charge pump without splitting the tractor? On some models it just bolts to the front of the HST. Not moving any oil under no pressure (filter removed) while turning seems like either pump isn’t turning or something got damaged when housing broke.

 

[The Haymaker]

Talking it through with a friend, I suspect the pump as well. Here's a copy and paste:

"There's a small amount of clearance between the shaft and 19. If I bent the shaft a little, I could have broken that inner rotor or sheared the key.

Oddly, I drove the tractor enough to take off blade and bucket boom, then another 150 feet. I stopped and it never moved again.

I thought I had pulled the shaft out of the clutch, but the crack in the bellhousing was pretty much closed up, so it had to still be in the splines.

This makes me think it was actually this pump."

I had originally intended on buying a new bellhousing at 4k, Im 1k in for the welding, so I guess I can do the pump at 1400 and still have something.

Because it won't gravity feed oil, Ive a faint hope the rotor is intact and it sheared the key, but I doubt it.

Sadly, I'll have to do the whole 8 hour teardown and 16 hour reconstruction again. Ugh!

 

[Harry in Ky]

Okay, so you can actually remove the pump inlet line from the tee in the main suction line? If you can do that, you can drain down the transmission/hydraulic fluid far enough to do so. Horse the lines apart far enough to slip a length of hose (like three feet or so) over the end of the pipe. Funnel some oil into that and fill it as much as possible. That will obviously reach the charge pump. You can start it up while pouring fluid in and see if it will pump something out to the filter. If you feed the pump directly and it still won't pump, then you don't have much pump left.

 

[The Haymaker]

On a positive note, I tore it down two hours quicker than last time.

Another positive, I found the issue.

A negative, I'm gonna have to up my game on my only fans page. :/

 

[Harry in Ky]

Wow! No wonder it won't pump. You didn't do that damage during your repairs, must have been some side thrust going on with the engine running while the case was busted. How deep do you plan to go? That shrapnel must have gone through the rotating groups as well.

Just my two cents.

 

[oldnslo]

With luck the charge filter stopped the vast majority of the shrapnel from reaching the main HST components.

Running the tractor after reassembly without charge pressure may have done some damage to the HST pump wear surfaces since there may have been a limited hydrodynamic bearing lube on these surfaces after sitting for several weeks.

 

[Harry in Ky]

I'm still not clear on all the details. The case broke, so both halves of the tractor are no longer aligned. How long did the engine run at this point? Was the hydrostat still moving the tractor at this point? Did the tractor quit moving after that? What all was done to get the tractor in the shop? Was it running during any of that? When it was taken apart what did the oil look like in the line from filter to hydrostat? Any or all of that could have bearing on what the inside of the hydrostat might look like now.

 

[oldnslo]

Harry
The way I understand the sequence of events happening.
1) some load shock broke the bell housing and tractor is still running.
1a) I am not clear on if load was removed from loader at this time
2) tractor is driven under its own power approximately 150 ft. This is possible even without working charge pump since the “closed loop” between HST pump and motor is already filled with oil. NOTE: this is based on mechanical control of the swash plate.

My suspicion is like yours the housing broke causing either thrust or side load on the charge pump causing it to seize. Once it seized there would be little to no debris movement from charge area to the main HST which might have saved the HST from catastrophic damage

This is unknown until HST pump is opened for inspection

 

[Harry in Ky]

When I look at the posted photo of the charge pump it's obvious it didn't seize immediately. The scoring, cracked and missing pieces didn't happen AFTER it seized. It was probably still pumping something while gradually tapering off in that regard. And are we sure it actually did seize? As ugly as it is, it may still have been turning, just not moving any oil. After sitting idle for the time the tractor was apart, draining and drying out, it's no wonder it wouldn't pick up prime, whether turning or not.