# JD 4990 steering problems



## crash22 (Apr 15, 2010)

My John Deere 4990 won't go in a straight line. It weaves, and pulls to the left, and when I slow down at the end of the windrow it will pull verry hard one way.. John Deere says its the charge pump. I've checked the steering linkages with no slack in any. Any ideas are very appreciated!


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## Blue Duck (Jun 4, 2009)

It sounds like you are having air cavitation in the steering orbital valve. Most likely its the charge pump. If the charge pump does not supply enough oil to the other pump it will cause all kinds of odd problems. Usually steering and 3 point are the first places you will notice it.


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## panhandle9400 (Jan 17, 2010)

It sounds like it might be out of time and needs to be set back to neutral, to check that it needs to be off the ground on drive wheels. Had a swather end of the season acting strange when you steered it and it was just out of neutral a little bit , steer hard one way and speed up when turned the other way ? hope this helps it talks about setting the steering in the book .


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## crash22 (Apr 15, 2010)

yeah it does speed up or slow down slightly.. We haven't used it this year yet, I'm just going off memory of symptoms of last year.. Its so bad that I never run it in road gear because it's 4x worse not safe for me or anyone else on the road.. If it was out of the neutral position wouldn't you be able to feel it pull to one side if you just take it out of park?

If one charge pump is weak and causing cavitation souldn't the proportioning valve from the aux. charge pump supply more pressure to make it run smooth? I don't know I am just trying to rule out all other options before I bite the bullet and buy a new pump.. Can I rebuild this pump? also does anyone know where to get a rebuilt pump cheaper than john deere? Thanks for all input!


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## lewbest (Dec 9, 2009)

I'll be first to say I know nothing bout your tractor nor if JD builds their own hydraulic stuff. I will say this though; I have a NH skidsteer that NH said no hydraulic drive parts were still available. The drive pump/motor units were Vickers but without any numbers on them so you'd have to get parts from NH. I started contacting internet hydraulic places; found this one. He said if he could see my old parts he could probably match them up. I boxed them up & sent them to him; he matched them right up & I got the piston set & some other odds & ends for about 400 bux. I told the guys at NH about it & they said the last price they had before they became unavailable was about 1800 for what I got. If you want to contact him here's the info: He's in Missouri

Zip Underwood
Knight Hawk Supply
Hydraulic Pumps, Motors, Valves, Cylinders, Parts, Seals, Maintenance Supplies
[email protected]

Great to do business with; he bent over backwards to help me (NO ONE at the local hydraulic places would try anything but try to cross NH numbers to Vickers numbers).

Lew


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## crash22 (Apr 15, 2010)

Thanks! I hoped someone would have some info like that!


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## Madsnake (Dec 25, 2009)

I would check the nutrel setting on the steering like it was sugested, skid steer loaders are the same and need a adjustment here and there. No a skid steer ya jack them up and have them running and see witch side wheels go witch way in nutreal than adujst the nutral stops so the wheels dont move in nutrel and they stop when returned to nutral
If that dose not work it could be the charge pump, I would find out what test there are for this and pressure test the system. I always strip a pump to make sure it has died before fitting a new one so you know that it will fix the problem, no good repacing a pump to find out the issue is coused by somthing else couse problem will still be there. Could it be sucking air from low pressure line? could there be a screen thats blocked for the pump oil feed in the tank?

I dont know your JD windrower but have worked for a long time fixing ag and earth moving equipment and I just out lined how I would trouble shoot it if this machine was out on our farm! We dont pay for any one to fix our gear lol we do it cheap!

Madsnake


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## crash22 (Apr 15, 2010)

I never thought or there being a screen in the line.. I'll check that out. Thanks for your help!


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