40c and 420c hydraulic pump

boler76 · Post by **boler76** » Fri Jan 05, 2007 6:44 pm

It sure would be nice to overhaul the hydraulic pumps when I redo these machines , but to date have been unable to find rebuild kits or new pumps. Anybody have any ideas? Thanks

Post by **Lavoy** » Fri Jan 05, 2007 9:57 pm

There are no kits or pumps left, I have heard that many of the internals are obsolete as well.
If the insides of your pumps are good, I normally keep gasket sets, o-rings, and bearings on hand.
Lavoy

JD440ICD2006 · Post by **JD440ICD2006** » Fri Jan 05, 2007 10:39 pm

Lavoy,

I believe I saw where there were two different pumps available on the 440ICDs, front pumps that is. Mine is a Cessna, do you have gaskets and o-rings for that model?

Post by **Lavoy** » Sat Jan 06, 2007 12:08 am

I probably should have qualified that, I meant for the camshaft driven pumps.
For the crank driven pumps, yes there was Cessna and Hydreco, with Hydreco probably the most common. I think the Cessna was more of a replacement pump, although I could be wrong. I have some Hydreco parts on hand, but nothing for the Cessna. Not sure on a source for Cessna parts other than maybe a local hyd shop.
Lavoy

boler76 · Post by **boler76** » Sat Jan 06, 2007 4:57 am

So much for the total restoration if the hydraulics cant be rebuilt, Whats the advice out there ? Thanks

Post by **Lavoy** » Sat Jan 06, 2007 10:10 am

There are some used parts, and some used pumps around. What is wrong with your pumps? If they are functional, new bearings, and o-rings will be all they need most likely.
Lavoy

boler76 · Post by **boler76** » Sat Jan 06, 2007 3:05 pm

Well they both work, one better than the other, The one with the least output pressure is the one I have already put new bearings seals and "O" rings in, its on the 420, the 40 has more pressure but neither are up to specs; 40 has 800psi and 420 has about 50 psi, still work though. I will probably have to live with them, just thought new gears and body would help, Thanks

Post by **Lavoy** » Sat Jan 06, 2007 10:43 pm

Did you shim the bypass in the valve to set the pressure?
Lavoy

Post by **JD40c** » Sat Jan 06, 2007 10:48 pm

And/or check the end plates, gears, body, for gouging? Lavoy can answer better than I, but I'd think if the bearings/bushings went out, the gears could dig into the end covers.

boler76 · Post by **boler76** » Sun Jan 07, 2007 5:07 am

I dont recall seeing any pressure relief in pump , I figured it was under the seat. As far as the gears and body go, it is them I wish I could replace, I refinished the endplates on a piece of glass with grinding compound and got the end clearance down to spec but the gears and centre body I dont know how to restore. Thanks

Post by **Lavoy** » Sun Jan 07, 2007 12:14 pm

The pressure relief is in the hyd valve, not in the pump. Look at your service manual, it will give you the specs.
Unless your gears look that bad, I wouldn't worry about it, I will bet you will get your pressure up just fine with few shims.
Are you running a straight weight hyd oil, or a common systems fluid?
Lavoy

boler76 · Post by **boler76** » Sun Jan 07, 2007 5:59 pm

Thanks for input, I will try shimming the pressure relief , I use SAE 30 non detergent oil in hydraulics. Thanks again

Bret4207 · Post by **Bret4207** » Sun Jan 07, 2007 6:56 pm

About how much pressure should they be running? My 40C has a 3 pt and blade. I used a Prince 2 spool control and the 3 pt seems to work fine. The blade acts like the pumps sucking air or not getting oil. I had to cob the suction line from 2 pieces due to rust and the bushing at the intake on the pump was a size my JD dealer had never seen, nor had anyone else, so I ended up soft soldering the pieces together to fit.

Barring the line or pump getting air, could the hyd cylinder (a generic 3"x 8") be the problem? Or maybe the control?

Post by **Lavoy** » Sun Jan 07, 2007 8:27 pm

Your valve may not even have a bypass, be sure to check that. Also, most valves will not go below 1500PSI, and you should only be running 1000 PSI.
I would check and make sure all of the hyd system is working correctly, then see if the cylinder works right.
Lavoy

boler76 · Post by **boler76** » Mon Jan 08, 2007 4:14 am

Every thing works properly but with a pressure gauge the 40 has 800psi and the 420 shows 50 psi everything works; just thought with an overhaul could get things back to original, my info says these pumps should put out 1800psi when in top shape, thanks for all the help

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