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  #1  
Old 07-28-2008, 01:59 PM
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Any Tractor/hydraulic Wizards Here?

My ancient Deere 2040 cannot be run but about 30-45 minutes in the summer before it overheats, making it pretty useless. When the ambient is less than 80 or so, you can run it for maybe 90 min before it gets too hot. This isn't exactly a new problem but, it does seem to be getting worse.

Background>
I've had the radiator out and checked (OK), the water pump out (OK), checked/changed the thermostat (OK), looked at the water flow into the top tank (seems OK) and I'm now running it without the thermostat (no change).

I'm beginning to think that maybe it isn't the cooling system that is the problem.

FWIW, it has a closed center hydraulic system and simply running the tractor without using any hydraulics (power steering and a loader are the only hydraulic appliances that it has) will eventually get the steering column and loader joystick body too damned hot to touch.

I'm thinking that for some reason, the hydraulic pump isn't destroking completely when it's not in use because of a leak/bypass somewhere in the system and the thing is pumping a little all the time, something IIUC, a closed center system isn't made to do thus heating the hydraulic fluid in the tranny housing and that, in turn, transfers heat via conduction to the cooling system.

Also, since I've owned it, the loader has always crept upwards (very slowly, almost imperceptibly) when you run the tractor.

Any advice?

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Last edited by R Leo; 07-28-2008 at 02:07 PM.
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  #2  
Old 07-28-2008, 02:13 PM
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Know a bit (very little bit) about hydraulics and I think your last statement needs further investigation and repair.

If the bucket is creeping up, then that means that most likely the valve that controls the bucket lift circuit is either not returning to "rest" when released, or has a bad seal on the pressure side that's allowing hydraulic oil to bypass.

The constant demand for pressurized oil will definitely result in a hydraulic system that is constantly working, and therefore placing a load on the pump, and the consequent heating of the oil as a result.

Combine the constant load of the pump on the engine, along with the heated oil and you've got a recipe for engine overheat.

Can you "giggle" the bucket lift handle and get it to stop creeping up? If so, then the valve is not returning to rest. If not, then I'd look at replacing/repairing the valve itself.

The bucket should definitely stay wherever you put it as long as the engine is running. It should not creep upwards. For one thing, it's not safe.

Hope this helps - good luck.
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  #3  
Old 07-28-2008, 02:20 PM
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Randy see if this is applicable to your situation. If not there is a wealth of information there otherwise
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  #4  
Old 07-28-2008, 02:32 PM
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This place is awesome.

John, thanks for the link, that's most promising and I'll look into it.

wbrian63, giggling doesn't change things.

BTW, the original pump destroyed itself about 4 hours after I bought the machine (three years ago). I had the pump replaced and installed a joystick control for the loader (the old unit was a two stick control). My tractor mechanic flushed the system and found a lot of metal debris at the time of the repair. I wonder of some of that stuff lodged in or damaged a spool in the new valve and is making it leak?
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  #5  
Old 07-28-2008, 02:34 PM
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You need some 5 weight ball bearings.......................Heyyyyyy its all ball bearings these days.
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  #6  
Old 07-28-2008, 02:39 PM
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Quote:
Originally Posted by Howitzer View Post
You need some 5 weight ball bearings.......................Heyyyyyy its all ball bearings these days.
Would synthetic ball bearings work? MoBall 1?
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Old 07-28-2008, 03:06 PM
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Quote:
Originally Posted by R Leo View Post
Would synthetic ball bearings work? MoBall 1?

Nope RoLLtella.
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  #8  
Old 07-28-2008, 03:13 PM
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Quote:
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Nope RoLLtella.
Waaa...
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  #9  
Old 07-28-2008, 07:51 PM
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A few well placed pressure gauges might tell you if there is pressure where there shouldn't be.
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  #10  
Old 07-29-2008, 08:10 AM
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try draining some of the fluid from the system and running it through a coffee filter. See if you find metal.

Joystick valves are more sensitive than their two-way counterparts to contamination - just by virtue of their more complicated structure (I would think).

As I remember the design of most hydraulic systems, the pump is designed to bypass harmlessly when no pressure is required (output line fully closed).

Open the output line by toggling a valve to a device, and the bypass on the pump closes and pressure goes to the device.

Your upward creeping bucket is placing a constant demand on the pump, and that's leading to heated oil and consequently heated engine.

Get the joystick serviced - I think you might find a stray shaving has nicked a seal and is allowing pressurized oil to constantly bypass the valve and create the demand on the pump.
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  #11  
Old 07-29-2008, 12:11 PM
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Quote:
Originally Posted by wbrian63 View Post
try draining some of the fluid from the system and running it through a coffee filter. See if you find metal.

Joystick valves are more sensitive than their two-way counterparts to contamination - just by virtue of their more complicated structure (I would think).

As I remember the design of most hydraulic systems, the pump is designed to bypass harmlessly when no pressure is required (output line fully closed).

Open the output line by toggling a valve to a device, and the bypass on the pump closes and pressure goes to the device.

Your upward creeping bucket is placing a constant demand on the pump, and that's leading to heated oil and consequently heated engine.

Get the joystick serviced - I think you might find a stray shaving has nicked a seal and is allowing pressurized oil to constantly bypass the valve and create the demand on the pump.
FWIW, I think you're right on the knicked seal. This thing has always acted weird when using the joystick...not unpredictable weird but slowing down towards the end of the bucket ram stroke and not making any power. Drawing the rams in it can lift 2000+ pounds but it can't push for squat.

It's either that seal, or the destroker valve in the pump is somehow hosed or has debris in it.

FWIW, I was also thinking that the joystick was a complicated device but I was surprised to discover that the complicated part is all on the outside with the linkages...the spool body looks pretty much the same as an old dual spool housing.

I should really save my bottle caps and buy a new tractor but I like this one because it can fit under the trees when I'm shredding and it's German.
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  #12  
Old 01-01-2009, 11:50 AM
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Eureka!

I may have finally discovered the cause of overheating in my venerable Deere 2040; something it's been doing ever since I bought the damned thing.

Since a new Kubota 8500M didn't arrive in Santa's bag, I resolved to get to the bottom of the overheating problem. In the process of resolving this issue, I had eliminated several of the potential problems: hydraulics, water pump, belt, fan and thermostat. I had also, run JD cooling system flush in the system as prescribed.

I had good water flow into the radiator and through it and, at one point about 18 months ago, actually pulled the radiator and took it to a shop where they pronounced it fit. This was my first mistake: assuming that the experts knew WTF they were doing.

Going back, I'm now confident it isn't the hydraulic system since, when the engine is overheating, the temperature of the transmission case and joystick return hoses never exceeds 150F or so while, at the same time, the engine is pushing 225-235F and is starting to open the pressure cap on the rad. So yesterday, I pulled the hood off, reinstalled the thermostat and proceeded to run the machine to operating temperature in order to check the radiator for 'cool' spots (ie plugged tubes) with a non-contact thermometer.

During the course of this, I also pulled the overflow hose loose from the filler neck and found that, shortly (5-6 minutes) after the engine was started, I had a slow but steady drip from the overflow. Once pressure in the system climbed a little (10-15 minutes), it was a mechanical pencil lead-size stream. It is leaking at such a rate that it would take 30-40 minutes to lose enough coolant to cause overheating....exactly what I'm experiencing during routine operation except that I thought that overheating was causing the coolant loss, not coolant loss causing the overheating!!!

I've looked at the overflow in the past but, only after the machine was hot. Never once did I see a leak but now I realize that the hose drains into a slight depression in the front axle housing and, I guess, if the engine and surrounding steel is hot, the coolant evaporates and disappears as soon as it hits the depression.

So, I shut down, pulled the cap for inspection and discovered a small crack in a brass apron just under the top of the cap. I also saw that one of the cams on the radiator neck was bent slightly downward, causing the cap to be pulled down tighter on one side than the other. I bent the cam back into place and replaced the cap with a new one but I still have a leak.

Right now I'm thinking that the radiator neck must have a leak in the solder joint between the sealing surface for the radiator cap and the collar that makes up the outside of the neck assembly. This sort of make sense because whatever hit the cap (possibly a falling branch?) and bent the cam downward probably cracked the solder joint as well. Also, a crack in that joint is the only thing that would allow low-pressure (ie less than the cap's rated pressure) coolant to bypass the cap's sealing surface and escape out of the overflow.

The radiator 'experts' simply weren't...apparently, they never tested the thing for pressure integrity. After taking it to them, I assumed that they'd done their job and, at that point, removed the radiator from the equation to follow other rabbit trails.

Tomorrow, I'm on the hunt for either, a radiator shop that can fix that neck or, a new radiator.

Jeez.
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  #13  
Old 01-01-2009, 12:14 PM
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Radiator shops are becoming a rare breed, so hopefully you can find one. That should be a quick and inexpensive job.

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