JD 444c hydraulic issues

[cjohnsen]

Background: it's a 1986 JD 444c that used to be my fathers. He had health issues so it sat for 10+ years before I tried to get it going again. I spend last year getting the motor going. I finally did and used it a little. Now I hadn't started it in 6+ months because work has been busy.

When I went to change the hydraulic strainer last year (right after I got the machine started for the first time) it was completely disintegrated and pieces of mesh and plastic got through the system. Here's a link of the post I made showing a picture of it : https://www.heavyequipmentforums.com/threads/jd-444-suction-strainer-part-number.56273/

I used it for probably 10 hours the last time it ran. The hydraulics worked but they were never as smooth as they should be. They would be a little jerky at times like something was holding the pressure up.

The other day I went to start it to move it and the hydraulics didn't want to work at all. The only way to get the bucket up was to rev the engine and keep pulling back on the boom lever. When the boom would move it would come up about an inch at a time. Same with bucket curling back. The boom down and bucket curl down work perfectly.

Now I'm not doubting there is crap in the system but I find it strange the hydraulics did work the last time I used it. And after a 6 month park they don't want to at all.


Here's the thing. The machine needs a new engine. I've got what I believe stuck stick rings on one cylinder and a hanging valve on another and it's got very little power. I had planned to get a new (used) engine and put it in as a project. But if it's going to have major hydraulic issues I may rethink that. Any suggestions what my issue could be?

 

[Delmer]

So this is a gear pump with basic open center valves? or what kind of controls? There's probably not a lot of knowledge of a 444 so help us out a little bit. Try to figure out what drives the steering and brakes, if they drive off the same hydraulic pump that drives the loader, then whatever controls those systems is where I'd look. Otherwise, start taking suction hoses apart and blowing back through components until you find the rats nest.

I agree, definitely figure out the hydraulics on the weak engine before doing the engine work.

 

[fast_st]

Might be able to overhaul that engine in place, hard to say.
Fix the primary tank strainer.
Clean all the junk out of the tank.
change the main hydraulic filter.
Get a pressure gauge on the pump output line, see if its clogged up.
check the steering priority valve.

 

[cjohnsen]

I'm not too familiar with hydraulic systems so I really can't say. I believe the stick in the cab for the boom and bucket go directly to the gear pump.

It has a brand new strainer and filter I put on when I realized the strainer was disintegrated 6 months ago.

On that thread someone commented and said the resivour tank only feeds the hydraulics for the boom and bucket. The steering, drive and brakes (what little brakes it has) all work fine. The only issue is the boom and bucket

 

[Mapleleaftrucks]

The brakes and steering work off the transmission oil, Some of these machines had gear pumps and some had vane pumps for the hydraulics, Would have to do a serial number check to see which pump you have

 

[fast_st]

Well, one way to find out is the digital method, find the main hydraulic pump, think its in front of the transmission, put your digits on the big lines and follow the hoses and see where they go! Also, clawing through the John Deere parts manuals online can give you some good idea of system components.

 

[Delmer]

Lacking any better advice, I'd concentrate on the tank to the hydraulic pump, it sounds like your pump is not getting fluid. Look for air leaks or blockages.

UNLESS you have pilot controls, then I'm out. Actually, still look at the suction side of your pump, you just need a manual to test the pilot controls IMHO. And by that, I mean somebody else will need to tell you how to do it easily.