69 JD 440A Charge Pump

krukedmatt · January 03, 2011, 07:36:03 PM

Hi, new to the forum. My dad cuts wood and is wondering how much of a job is it to replace the charge pump? Does the skidder have to be broken in half?

Any input is appreciated.

Thanks!

snowstorm · January 04, 2011, 06:03:26 AM

why do you think the charge pump is bad? its job is only to feed the piston pump

krukedmatt · January 04, 2011, 07:46:22 AM

Every so often, we can't pick the blade up or steer, but, after waiting awhile or playing with the steering for awhile, it will come out of it. We had the front pump rebuilt within the last two years thinking that was the issue.

Working back from that, we were thinking that maybe the charge pump isn't supplying the necessary pressure to operate the front pump?

Any thoughts on what this could be? We were wondering how easy it is to replace the charge pump?

Thanks!

Gary_C · January 04, 2011, 10:10:44 AM

I am not familiar with the hydraulics on that particular machine but most JD and other farm tractors have a priority valve in the hydraulics that gives top priority to the steering and brake circuits in the hydraulic system. Problem is that priority valve tends to stick with any foreign material that gets into the system and will sometimes stick when it is cold. On most machines it is called a MCV or multiple control valve.

Find that MCV valve and carefully take it apart and carefully clean it. Just make sure you get all the spools and valves back together correctly.

TeaW · January 04, 2011, 12:27:35 PM

Its not that hard to get at the charge pump if you need to. I did it on the landing in the bush 2 years ago but I had no hydralics at all.Take the battery's out and drain transmission take the cover off trany and the charge pump is right there.My problem was that the pickup tube had fallen out of pump it is held in with a O ring. Replaced the Oring and brazed a loop on to tube and wired it ,no trouble since. Welcome to the forum and good luck.

snowstorm · January 04, 2011, 05:56:35 PM

prioity valve would be a good place to start. just take it out. i did with mine. but pushing wood up climbing the pile if you lift the blade breaks wont work. dose yours still the old blade valve? square one?they were trouble along with the steering valve. priotry valve is by it self rite side above sterring valve. bout 6" long take the hose off fitting spool spring round piece. put it back together. did you set the stand by pressure after replacing pump??? its a closed center system.

krukedmatt · January 04, 2011, 06:14:50 PM

I have printed these responses off so that my dad can take a look in the woodyard, locate those valves and investigate.

Also, yes, remembered to set the pressure.

Many thanks!

snowstorm · January 04, 2011, 07:22:03 PM

i am sure you know this....if diff lock is down it wont steer

Bobus2003 · January 04, 2011, 09:20:40 PM

I'd be willing bet its the priority valve.. My 440 has this same problem and thats where my issue is.. When it won't steer, or the blade chatters, tap the brakes and mine straightens out.. somedays faster than others.. I just don't have the $$$ to fix the valve

snowstorm · January 05, 2011, 06:09:18 AM

dosent cost anything to take it out an try it. housing stays there. remove spool spring. one other thing look an see if the return spring is there for the break pedtal.

krukedmatt · January 29, 2011, 10:16:59 AM

Well, we had tried getting by for awhile, but yesterday the hose blew right off the priority valve. We took the spool out of the priority valve out and it looked pretty chewed up. We got a new one, put it in and replaced the hose, but now we have no steering and can't lift the blade.

Any suggestions for what it could be? Next step?

Thanks.

Bobus2003 · January 29, 2011, 12:56:07 PM

Quote from: krukedmatt on January 29, 2011, 10:16:59 AM
Well, we had tried getting by for awhile, but yesterday the hose blew right off the priority valve. We took the spool out of the priority valve out and it looked pretty chewed up. We got a new one, put it in and replaced the hose, but now we have no steering and can't lift the blade.

Any suggestions for what it could be? Next step?

Thanks.

Did you get the air bled out?

snowstorm · January 29, 2011, 02:01:16 PM

Quote from: krukedmatt on January 29, 2011, 10:16:59 AM
Well, we had tried getting by for awhile, but yesterday the hose blew right off the priority valve. We took the spool out of the priority valve out and it looked pretty chewed up. We got a new one, put it in and replaced the hose, but now we have no steering and can't lift the blade.

Any suggestions for what it could be? Next step?

Thanks.

take the spool and spring out it will work with out it. if that dosent do it let me know

sandhills · January 29, 2011, 04:41:42 PM

I would love to see a service manual for one of these, it sounds exactly like a problem we're having with a tractor of my dads. It's a JD 4010, I'd be willing to bet the piston pumps are the same or very similar. On our tractor there is a de-stroking valve on the bottom of the pump that you can adjust to manually destroke the pump (which basically puts the pump in nuetral) and the valve itself has a small oriface on the top of it. If any metal or foreign matter plugs the oriface pressure builds behind the valve and won't let it open, you might check on that. We changed the charge pump in the tractor also before figuring this out.

krukedmatt · January 30, 2011, 04:40:40 PM

Well, we took the spool out of the priority valve and also tried bleeding it, but there isn't any hydraulic pressure. We put a hydraulic pressure tester on the front pump and there is no pressure at all. Stilll thinking charge pump, does that make sense?

redlaker1 · January 30, 2011, 05:30:35 PM

have never worked on or even looked at a 440 skidder, but it doesnt sound like a charge pump you are talking about. I would call that an implement pump if it feeds the blade and steering. is it a tandem pump setup?

almost sounds to me like you have something floating around in your hydraulic tank and intermmitantly blocking the intake, or some other issue on the suction side of your pump. collapsed hose or an air leak.

snowstorm · January 30, 2011, 08:10:55 PM

haveyou taken the trans filter out yet???left side big round hole in frame. there is also a intake screen on the bottom of trans. been a while but seems like there is 3 bolts on the cover . just got back from sanding roads it down to 0 and i dont want to go out to the garage for the jd book but i will look tomorow. what part of the country are you? they have wet brakes so when the pads wear out all that stuff ...rite to the pump. remember charge dose not work with clutch in. the pump is turning??spline on coupling ok?? you can pull a piston out of the pump see what it looks like. change filter first cut the old one apart see whats in it. had one once that a peice of nylon from the locknut on the steering cyl went thru the steering valve that took a while. you said you set the stand by press???

sandhills · January 30, 2011, 09:57:26 PM

I'm with snowstorm, check everything easy and cheap first (filter, screens) this does not sound like a charge pump problem, can anyone here post a diagram of the main pump on one of these? This sounds way to close to what I'm dealing with and just seeing pictures of them and knowing the year I would bet they're almost identical setups.