# Skidder hydraulics overheating



## Barnie (Sep 18, 2014)

Hi
I have a 95 John Deere 648e grapple skidder and I am starting to have an issue with the hydraulics system overheating. I changed the hydraulic oil and filter along with a new breather for the tank. all attachments work fine, no loss of hydraulic power, recently had a hose break and it drained the system. can it be an air lock somewhere in the system like the oil cooler ?? the lines running to and from the oil cooler are hot as well. 
have any of you had a problem like or similar to this on your skidder ???


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## northmanlogging (Sep 18, 2014)

Got enough and correct fluid in there? and is the radiator for the oil cooler plugged up with dirt?

Lastly and hopefully not this did you cavitate the pump when you blew said line? My experience air tends to work itself out, takes some time in the cylinders and what not, but the pump filter and what not do ok.


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## 2dogs (Sep 19, 2014)

I would check the cooler first and make sure it is clean. Is there a strainer along with a filter?


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## Swamp Yankee (Sep 19, 2014)

Don't guess, find out where the heat is coming from.

Rather than guess where, get an infra-red thermometer and start scanning the hydraulics system for hot spots. If there's a restriction / issue the component will be hotter than the rest of the system. Check the temp of the line in and line out, big difference is a clue. Don't forget to check all actuators in both forward and reverse, extend and retract. Prior to doing this be sure to clean, power wash if possible the machine as dirt, and other assorted crud will act as insulation giving inaccurate readings. A thorough cleaning will also help increase air flow around the components and will help dissipate the heat. May not be a solution but can't hurt. Who knows, you may find a pinched or crimped line causing a restriction while doing the check.

Drain some hydraulic fluid and check for water contamination. If it's a milky brown color you've got issues and the fluid needs to be replaced. Water contaminated fluid loses its lubricity causing increased heat. Smell the fluid as well. Hydraulic oil that has been "cooked" will have a very distinct burnt smell.

What weight and how old is the fluid are you running? What has the local temperature been lately? Back in a previous life when I engineered winch systems for commercial and DoD applications we used to see a lot of heat problems with low viscosity oils in the hydraulics during summer. Is your machine running hydraulic oil or ATF?

Are you getting a lot of chatter in the hydraulics? Jerky, inconsistent performance is a sign of air in the system. Look for foaming of the fluid to confirm. 

Hard to trouble shoot an issue over the internet but hopefully this will help with a place / direction to start.


Take Care


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## Barnie (Sep 19, 2014)

Swamp Yankee said:


> Don't guess, find out where the heat is coming from.
> 
> Rather than guess where, get an infra-red thermometer and start scanning the hydraulics system for hot spots. If there's a restriction / issue the component will be hotter than the rest of the system. Check the temp of the line in and line out, big difference is a clue. Don't forget to check all actuators in both forward and reverse, extend and retract. Prior to doing this be sure to clean, power wash if possible the machine as dirt, and other assorted crud will act as insulation giving inaccurate readings. A thorough cleaning will also help increase air flow around the components and will help dissipate the heat. May not be a solution but can't hurt. Who knows, you may find a pinched or crimped line causing a restriction while doing the check.
> 
> ...


Hi
I did find one valve in particular that was heating up just as fast as the hydraulic pump , its the steering priority valve. Im running normal hydraulic oil and I'm getting full power in the hydraulic system, no foaming, one thing i see when checking the hydraulic tank tank before operating is condensation in the cap (which is a cast iron cap). just a couple of beads of condensation which i clean off.(I did replace the breather for the tank)


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## 4x4American (Sep 20, 2014)

Are you sure it's overheating or did you just notice that it gets hot when working?


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## hanniedog (Sep 20, 2014)

Is there a problem with the new hose. Maybe smaller inside diameter or possibly smashed a bit.


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## Barnie (Sep 21, 2014)

4x4American said:


> Are you sure it's overheating or did you just notice that it gets hot when working?


it gets hot within 5 mins of idling and not touching any attachment hydraulics,


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## Barnie (Sep 21, 2014)

hanniedog said:


> Is there a problem with the new hose. Maybe smaller inside diameter or possibly smashed a bit.


Ill be checking that also.


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## Barnie (Oct 2, 2014)

Well I put a new pressure relief valve in the steering priority valve and its still overheats, its looking to me that I may have a worn hydraulic pump which will be around 5-$6000 for a new one. We checked everything and cleaned the priority valve. Im hoping it may be something as simple as a backing spring on the swash plate in the pump itself not up to par. innards of the pump may be dirty also and the swash plate won't close fully. in other words somethings making my pump stay on. when i move an attachment the engine idles nice but when i stop moving that same attachment the engine idles right down. i got full hydraulic power all round, just the pump, steering priority valve and hydraulic tank get really hot after 5 minutes of idling without moving the blade or grapple...


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## Watson394xp (Oct 15, 2014)

There 2500$ on te 640E Caleb skidders I have 16000 hrs on the machine an it's on its 3rd one.. Change it urself tere fairly easy don't pay deere to thAts crazy!!! Good luck


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## Barnie (Oct 17, 2014)

Watson394xp said:


> There 2500$ on te 640E Caleb skidders I have 16000 hrs on the machine an it's on its 3rd one.. Change it urself tere fairly easy don't pay deere to thAts crazy!!! Good luck


I got the pump looked at by john deere and the hydraulic tech at a local paper mill and they both said the pumps fine other than a little cavitaion on the head which i got fixed this week, ill be reinstalling it on monday and trying it to see if it does the same, I can take that pump out in the pitch dark without any source of light, its my fourth time taking it out.


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## Watson394xp (Oct 17, 2014)

Haha gotta love it man.. I done ours twice in one week one time because we nvr flushed te lines an the metal shavings trashed the new one!!!


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