420 came off the trailer,need help

Did you lube the charge pump parts with oil before asembly, even a little Vaseline would be good to help the pump prime at startup.

After putting it back together, did you reinstall it, and try verify it still doesn't work, even the power steering?

Like I said before, the chage pump has to be working for the power steering (and implement lift) to work.

If they are NOT working, that shows the charge pump is not functioning.

The charge pump HAS to be working, to fill the main hydro pump and motor with pressurized oil before the hydro can even attempt to move the tractor.

Try not to run it anymore, 'til you figure out why the charge pump is not working.

The piston pump commutator plate, and slippers are lubed by oil pumped the charge pump. Without the charge pump flowing oil, all that stuff is running "dry", and will wear and/or seize up in short order. Without the charge pump pulling oil up from the transaxle, the whole hydro unit is "dry" of oil.

Since this thread is getting "lost" off of the bottom of the page, email me, if I can be of any more help.

bigcoulee@hotmail.com

Now, enough of the basics and to try and help you get your JD up and running again. Go to this site and ask the great people there if anyone has a good used pump.

Link

They are going to say yes and proceed to ask $350.00 with exchange for another pump. You will be getting a good used pump. You may even be informed that a pump will cost over $1500 to rebuild it. Sure.... IF YOU buy everything piece by piece which is like buying a car piece by piece.

Now a little more info for you. You could go to the Sauer Danfoss website and look up a distributor of their product that is near you. You can ask the distributor two things. Can they send your pump in for rebuilding which they should be able to do. At this point ask how much this will cost. And you can ask if your particular model is still available new. You will need to provide all pertienent tag information on the pump.

Link

The above is their website. I dont know what the cost is for rebuilding however it definitely isn"t anywhere near $1500.00. Good luck and let me know how you come out.

I stand by may advice to check the oil level and the charge pump.

Why are you arguing with the basic facts of how the system works???? The charge pump DOES supply pressure to the the power steering. Since his POWER STEERING doesn't work, there's something wrong, besides the commonly damaged hydraulic MOTOR.

The piston-type hydraulic MOTOR is often damaged when one of these machines moves without the engine running. It is always the FIRST thing to suspect. This, alone, however, doesn't explain the power steering not working.

jdjunkie,

If you decide NOT to tear into the hydro yourself, I can fix it up for you darned reasonably with some good used parts I have.

Email me, if interested.

bigcoulee@hotmail.com

You state that only the motor is damaged when such a thing as what happened to this gentleman"s tractor. Interesting thought. In truth the whole system ends up being damaged. Another thought to consider. If there are broken pieces of metal in the system then you have introduced contamination into that system. Would you rebuild this unit and use some fo the "appear to be good parts" or scrap the whole unit?

Now another thought. If the power steering isn"t working and the charge pump supplies the fluid to it then there is a very good chance the charge pump has been damaged. Or a simple thing such as a pin connecting the drive shaft to the hydro unit may have sheared.

The 15U consists of a charge pump, a main pump and a hydraulic motor.

I would like to inquire how you say the charge pump is the main pump system on this unit. It is after all a Sunstrand 15U series is it not?

One final thing. Please e:mail me because I have a friend that has a really nice 318 that a prebious owner had put 50 weight or heavier oil in the transmission and actually ruined the whole hydro. He would like to get it rebuilt or purchase a good used 15U for his 318 reasonably.

As always .... keep up the good work and smile while doing so.

Also... what about the implement relief spring's relationship with a charge pump?

(Just gotta smile a little more often.) :+)
I'm not replying anymore. We both know the gentleman has his answer to his question.

The gerotor CHARGE PUMP for the hydrostatic PISTON pump supplies pressurized oil to operate the power steering, in addition to it's "charge pump" duties.

I understand what the piston HYDROSTATIC pump does.

Between myself, and an aquaintance who is a Deere mechanic, we have repaired at least 7 or 8 hydros of this type that have been "killed" by falling off of trailers, or being towed excessively.

In EVERY one we've worked on, damage has been limited to the hydrostatic piston motor... to the "slippers" on the pistons and/or the commutator plates and piston blocks.

MOST of the debris has been in the motor area, to.

We disassemble, and thoroughly clean the complete hydro, and replace parts as needed with good used or new.

We have never had a comeback, or a problem I know of, and some of the ones we have repaired have been operating for YEARS.

Hey, we're just a couple of "rednecks", and this is no "ISO 9001" operation, but we've had good success, and we're CHEAP!

Probably not right in your eyes, but it's hard to justify a $1800 hydro for a $800 to $2500 tractor!

You can call Deere Techpubs @ 1-800-522-7448, with credit card in hand, to order a Techinical Manual.

Here's a diagram from jdparts.com. The "charge pump" is Key #20. Pin, Key #13 is a prime suspect.

HOPEFULLY, it's skid to a stop on the road didn't wreck the MOTOR section of the hydro!