47 2n hydraulics rebuild progress

lennyzx11 · Apr 6, 2017

I had a little time today between three year olds naps and rain to get the 2n pump dropped out. I had removed the lift cylinder prior and only had to remove the top cover this time.
Short version.
Removed all three drain plugs working from back to front of the rear axle,hyd pump, & transmission. About 5 gallons come out so be ready with that much capacity in drain pans.
Removed top cover. (Again)
Removed 4 bolts holding PTO shaft housing on rear of axle and used a chisel to gently tap it apart at bottom and top the used screw driver to work it loose. Removed pto shaft.
Removed all bottom bolts holding pump in place. Then pried/chiseled (GENTLY !) around base gasket to break pump loose from main housing. Once loose. Pump has to be slid back in order to clear front in order to drop down. Then it'll fall out so be ready with a catcher or a jack. Mine landed on the piece of old foam rubber I had under it happily.
Then after wiping most of the oil off, I took it apart. There are springs, valves, and rods, hidden inside various passages that don't fall out easily but can come out as you are cleaning so make sure you get everything out. I had to use hemostats in a couple of places to get everything out.
Looking from front of tractor, here's mine just out.

Notice the longer 4 bolts on one side for the valve blocks? There's a difference.

I must have not got the break down picture that thought I had so will take it tomorrow all laid out.

Tore everything apart, three year old granddaughter woke from nap and we went to town for diesel and ice cream. When returned home, all is soaking overnight in diesel.
Granddaughter soaking in tub with chocolate ice cream residue while soaking grandmother splashing while grandpa is hiding out in shop!

Though I ordered a "complete" kit, and a control valve, it appears I didn't get a pressure relief/safety valve. So I think I'll order it now. Not sure of a way to test the old one with layman's tools.

Found two valve springs broke and control valve assembly has a chunk out of it so far.
I think that was from previous owner removing lift cover without disconnecting control rods to valve though. I found it loose inside and hanging originally.

Soundguy · Apr 6, 2017

If you wanted to go to the trouble to check the relief, you could did something with compatible female threads for the relief, then plumb in a 3000 psi gauge, fill tho manifold with gear oil, then plumb I a grease gun.. Many of those are good for around 4000 psi.

Your relief should operate somewhere in the 1500-1700 psi range.

Tho rig is easiest dome with a custom aluminum bullet with 3 tapped holes, relief, gauge, gun.

Me? I'd either replace it with the rebuild, or not, and test it with the pump back in and no cover. Set a ball bearing over the hole, then use 2 bolts and a piece of metal to hop the ball over the oil port on the casting.

Add an orb fitting and gauge to test port, set control valve to lift, and then spin that pto with a pipe wrench..

lennyzx11 · Apr 7, 2017

I'm replacing it. I thought as much that it would take some rigging to actually test it.
Thanks for the info though!

lennyzx11 · Apr 8, 2017

Got the pump cleaned up and back together today. Pretty straight forward but did have a few details to mention I ran into as a first time rebuilder.

Here is a picture of the scotch yoke assembly all back together which it has to be assembled before installing back inside the pump housing.

See how the brass wear pieces have a "flange"? Those must face to the center.
The driven cam shaft that the PTO shaft goes through has a front and back also. See the recessed lip on the end facing us? It mates to the lip of the brass/bronze wear piece laying next to it.

One other thing to mention. Looking closely at the cast pieces round pivot ends you'll see the one closest to us dull and rough looking. Yep, it was not machined to final standards during manufacturing. Consequently it wouldn't fit into the holes in the valve chamber bodies it was supposed to. No matter if you try to put it together 800 different ways and use compound creative cuss words, it won't fit! I measured the wear on my old ones and used them as the measurements for old and new were close.

lennyzx11 · Apr 8, 2017

Picture of the mocked up inner assembly. I mounted one chamber body on the pump housing and fed the yoke assembly inside to align with the two holes of the valve chamber.
Make sure the gaskets line with the holes on housing and chambers. It can be put together wrong.

Looking closely at the chamber's bolt holes two on each assembly have a taller hole than two others. Long bolts should be in tall holes. Mine wasn't so some long ago mechanic/farmer missed that.

lennyzx11 · Apr 8, 2017

Here's a picture of the valve assemblies. One laid out in line and one assembled correctly next to it.

Then a picture of the assemblies all the way in their valve bores. This takes a bit of wiggling with a finger to get that check valve to go past that last lip. I laid the pump on the side for this part.

The lift cylinder and its pieces are all soaking in the diesel for clean up. Then I'll use the diesel "bath water" to clean out the tractor's housing before reinstalling the new/rebuilt parts.

I have been summoned by three year old granddaughter for a tractor ride to "move dirt!" So this is on pause.

lennyzx11 · Apr 20, 2017

Well, got everything back together but it appears I get to take it back apart. The lift does raise now albeit slowly.
Looking in the dipstick cover hole, I see oil pressure flowing out of the back of the pump. Where this side valve chamber is mated to the center block. There is a gasket there and it has to be installed correctly. I'm fairly sure the gasket is oriented the correct way and the bolts are tight but something is definitely not right. The fluid volume and pressures varies with the quadrant lever movement so I know the new control valve and relief valve are working.

Back to the drawing board.

Here's some pix of the assembled /
2n lift cover. It can be done wrong. Don't ask how I know.