# My 6420 John Deere tractor



## overthinker

Greetings. We purchased a John Deere 6420 tractor-barely used (750hrs). We had been using a CaseIH MX100c fwa as our main feeding tractor for many years but the hours were piling up (13000) and we were concerned about reliability issues going forward. The John Deere is a beautiful tractor to use, but we have some issues. It wasn't long before we realized it seemed hard on fuel - seemed like we were constantly fueling up. Is this a common problem with this make and or model of tractor, or is it just my tractor? I try not to have a bias towards any particular color of tractor, and the MX did have a 4 cylinder Perkins motor.... Sad, but we contemplate using the JD less or trading it off because of this. We can't go a whole day baling without running out of fuel! The other issue we have is hydraulic oil overheating. Periodically the warning light flashes saying the hydraulic oil temp is too high-don't think it's oil or filter related. Is this a simple fix? Any advice, thoughts, or opinions welcome. Thanks


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## SVFHAY

What transmission?


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## overthinker

24 speed transmission


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## Vol

6420 burns about 5.5 gallons per hour under max hp load according to tractordata. Is this about what its using when you are working it hard? The 6420 is about 20 more PTO hp than the Case according to tractordata.

Regards, Mike


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## slowzuki

If your fuel use is up and the oil is heating up, you are likely in constant pumping on your hydraulic system. I can't remember if all the 6420's have close centre hydraulics but if yours is, something must be making the pump go to full discharge and the relief valve is dumping creating heat. If you are open centre its usually easier to find as something will misbehave in the hitch, remotes loader etc.


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## SVFHAY

My 6420, 16v common rail engine with ivt , would burn 1.5x the fuel that my 6410 did when really working hard but it was gettin more done. Closed center hyd alnost certainly unless it was a really stripped down model so maybe slowzuki is onto something. I don't think the 24 speed has the accessory water pump like the ivt does for hyd cooling or I would blame that.


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## Grateful11

205 4x4' round bales baled here today in about 6 hours. The tank was on 3/4 when it started and had a 1/4 tank when finished, so about 17 gallons of fuel. The CaseIH 5140 with the Cummins engines is pretty fuel efficient. It's ashamed that they keep adding more emissions controls to tractors but they seem to be less fuel efficient.


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## 69zfarmer

Kubota M105X here comparable to the 6420 it also loves fuel.Tractor Data does not have much info on Kubota's.


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## D.C.Cattle Company

I had the same hydraulic issues on my 6410. Warning lights would flash at start up and sometimes while running. It ended up being a low voltage problem with a discount battery I had installed. Somehow it triggered the hydraulic sensor and gave the illusion of hydraulic issues when it was voltage issues. Purchased a good quality battery and the probelm disappeared.

Cant help u on the fuel issue. My 6410 seems to make fuel.


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## Colby

Our 6420 uses half a tank to 3/4 a tank cutting hay or shredding. That's the hardest work it does. We had the hydro oil over heating on our 7320 last year but that was running hydraulic rakes


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## longtexan71

It may be a simple fix on hydraulic temperature. Bring the air hose to it and blow out coolers and radiator. And my 6420 has never had anything but John Deere hydraulic fluid in it I'm Not a fan of cheap oil at all. Only problem I have had with hydraulics is with leaking couplers. Our 6420 stays on baler most of the time but can run a r2300 Vermeer rake all day and not give a lick of trouble. I am sure you are aware of the controls above couplers to change flow rate and function. As for fuel use I feel like ours is efficient enough but we operate at low rpms seldom ever over 1700 mostly at 13-15 rpms in our use on baling. However If it still has brown cloth fuel lines take all of them off and put on rubber. If its running rough its getting air in system tan lines were horrible about this. We had to rebuild the injection pump because of this. Once we did this no problems what so ever. Your JD tech can tell you more about this. Ill share more if you like I hope this helps.


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## slowzuki

Searching around net the 6420 seems to have a lot of overheat issues. There are JD tech bulletins out too. Very strange cooling system with cooler in the tranny and split rad with two temps, one for motor one for oil cooler in transmission. Seems to be an air pump inside the transmission as well to move oil between major castings.

Also the usual stuff like 3 point limits causing hitch to be always lifting if you raise it all the way, hydraulic remotes stuck in pumping or leaking etc. Apparently even leaving them in float can cause issues.


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## overthinker

Wow ...Thanks to everyone for all the input! I'm intrigued by the thought that the hydraulic oil overheating might be the cause of the excessive fuel usage. I just assumed they would be unrelated problems. So now what? What should I do first? Can't be as simple as changing the flow settings @ the back, can it? We blow out all the rads @ the front EVERY DAY before using it to try to prevent overheating. Is it logical to think that if we solve the oil problem, it might also solve the fuel usage problem? This is probably above my pay grade! Hate to send it to the dealer - I'll be without it forever and they'll charge a fortune ...


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## gradyjohn

Fuel - check your turbo. Oil - is it JD compatable? It will say on the bucket. Some hydraulic oils are not. Oil cooler could be clogged. Blow it out as stated above.


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## Grateful11

Here's something really good for cleaning radiators, picked up a set a couple weeks ago at our local JD dealer.

http://www.radiatorgenie.com/


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