Hi, I have a Hitachi EX100-3 excavator that is overheating after 30-40 min work in around 35 degrees celcius temperatures. It seems to be ok with light work on cooler days but pretty bad on these hotter days. After pulling the radiator out and having it cleaned I decided to check the water pump while the radiator was out. Upon pulling it out I noticed that someone (presumably one of the previous owners) has at some point over the years blanked off the bypass pipe that runs between the water pump housing and the bottom of the thermostat housing. Could this be the problem?
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Hitachi EX100-3 Overheating
- Thread starter Tim78
- Start date
Tones
Senior Member
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- Mar 15, 2009
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- Ex land clearing contractor, part-time retired
G'day Tim and welcome to HEF. Not having the hose connected may be a cause. I would reconnect it, it's a cheap fix. If I remember the hydraulic oil cooler is on the outside of the radiator, have you checked thats it clean. Also get yourself a heat gun (infa red thermometer) to check the hydraulic oil temp at the cooler. Hot hydraulics cause the the water temps to climb.
In those temps on an excavator, the air flow is critical. The temp gun will tell you how much hot air is going back around the radiator for a second pass through. That will cause overheating even with a perfectly clean radiator.
How bad was the radiator plugged? water and air sides?
The bypass typically is open when the thermostat is closed, for circulating water through the cold engine to keep the temp even, it might not have any affect in your situation. Have you replaced the thermostat? IF you're not running a thermostat, leave the bypass closed.
How bad was the radiator plugged? water and air sides?
The bypass typically is open when the thermostat is closed, for circulating water through the cold engine to keep the temp even, it might not have any affect in your situation. Have you replaced the thermostat? IF you're not running a thermostat, leave the bypass closed.
Knivens894
Well-Known Member
I have a JD 490E which was hydraulic system overheating. I started like you with the radiator and thermostat, resealed around the radiators, etc. That was 6 months ago, many thousands of dollars in parts later, with two field service calls by JD techs and the problem persisted. I used a IR heat gun to determine the overheating was caused by the hydraulic system. After a 6 month long chase, the problem turned out to be caused by low pilot pressure. Somehow the low pilot pressure caused the main pump to increase flow, above what the system needed, and the excess flow blew through the relief valves, creating heat. Start with the main pump solenoid valves, check the coil resistance per the test and operations manual. Then disassemble the solenoids to be sure a spring has not broken and wiring is intact. If there are no issues found there, check the PVC for codes. If none are found, check the main system relief valve pressure settings, then the pilot control regulating valve and control valves against pressure specifications.
Please be very careful running the machine at high temps. It appears the hydraulic heat in mine over time has caused all the pilot system valve springs to weaken and at about $700 each from JD, it is going to cost a wad to fix it completely. Replacing the pilot regulating and control valves fixed my heat problem. Now I am dealing with pilot control solenoid circuit pressure issues.
Along the way, the main pump was removed, disassembled, inspected and reassembled. No issue found there. The Tech said the problem was the engine injector pump, (I did not believe him, but he said he had seen it before) so I removed it and had it overhauled (No Change). Then I was told it was the PVC, so I bought a new one and installed it, (again no change). The op and test manual said if the machine shuttered in swing at power level "L", the swing brake was not releasing, so off came the swing motor and it was disassembled, inspected and resealed, (no change). The oil cooler control valves were removed individually, the machine run without them (no change). Others on this site said to reseal the pilot control system which was also done (again no change). We leak tested the swing motor (met specs), looking for a leak by under pressure situation. The main system pressures were adjusted to specifications( no change). Main pressure relief and surge reliefs were set to specified pressure (no change). The angle sensor, P sensor and DP sensors were replaced (no change). It was not until I found the low pressures on the pilot regulator and control valves and replaced them to specifications that my heat problem went away. The heat was created by the main pump being told to increase flow when the flow was not needed. The multiple reliefs simply passed the pressure to prevent system overload, creating heat. The heat source was spread out over all the relief valves in the system, making it impossible to define an exact heat source.
Please be very careful running the machine at high temps. It appears the hydraulic heat in mine over time has caused all the pilot system valve springs to weaken and at about $700 each from JD, it is going to cost a wad to fix it completely. Replacing the pilot regulating and control valves fixed my heat problem. Now I am dealing with pilot control solenoid circuit pressure issues.
Along the way, the main pump was removed, disassembled, inspected and reassembled. No issue found there. The Tech said the problem was the engine injector pump, (I did not believe him, but he said he had seen it before) so I removed it and had it overhauled (No Change). Then I was told it was the PVC, so I bought a new one and installed it, (again no change). The op and test manual said if the machine shuttered in swing at power level "L", the swing brake was not releasing, so off came the swing motor and it was disassembled, inspected and resealed, (no change). The oil cooler control valves were removed individually, the machine run without them (no change). Others on this site said to reseal the pilot control system which was also done (again no change). We leak tested the swing motor (met specs), looking for a leak by under pressure situation. The main system pressures were adjusted to specifications( no change). Main pressure relief and surge reliefs were set to specified pressure (no change). The angle sensor, P sensor and DP sensors were replaced (no change). It was not until I found the low pressures on the pilot regulator and control valves and replaced them to specifications that my heat problem went away. The heat was created by the main pump being told to increase flow when the flow was not needed. The multiple reliefs simply passed the pressure to prevent system overload, creating heat. The heat source was spread out over all the relief valves in the system, making it impossible to define an exact heat source.
mitch504
Senior Member
An exhaust leak blowing in the wrong place will cause a hard to diagnose overheat. You can spend a lot of time chasing your tail with that one, (not like I'd ever miss that. 
)
)Wilson892
Well-Known Member
Y
Knivens894
Well-Known Member
My current recommendation would be to run the machine until it is hot, leave the power setting where you had it, and close the pilot control valve. If the temperature drops, you will know it is in the hydraulic system, specifically the pilot control system. On mine, I went through every system, not understanding or paying attention that when the pilot controls were off, the temperature dropped. In my machine, it was entirely in the pilot control system. The lack of adequate pilot control pressure causes the PVC to call for more pressure which is dumped through the relief valves causing heat. Specifically the main relief (at 5,000) and the swing reliefs (also at 5,000). Since the reliefs are spread apart, it makes identification of the source difficult with an IR heat gun.
I went through 6 months of inspection, repair and replacement of parts until I finally found it. The pilot regulating and reducing valve springs were very weak and the required pressures could only be obtained by replacing them. Once the pressures were to specs, the heat problem went away completely. My belief is the low pilot pressures cause signals to the PVC to increase the flow in anticipation of work, and because it is not needed, the excessive flow is dumped through the relief valves. Good luck with yours! If the temperature does not drop with the plot controls off, it may be in the engine systems, but had I know what I just suggested, I could have saved a wad.
I went through 6 months of inspection, repair and replacement of parts until I finally found it. The pilot regulating and reducing valve springs were very weak and the required pressures could only be obtained by replacing them. Once the pressures were to specs, the heat problem went away completely. My belief is the low pilot pressures cause signals to the PVC to increase the flow in anticipation of work, and because it is not needed, the excessive flow is dumped through the relief valves. Good luck with yours! If the temperature does not drop with the plot controls off, it may be in the engine systems, but had I know what I just suggested, I could have saved a wad.
Huffa
Well-Known Member
Sorry to drag up this oldie but its really interesting to me and I'm after some advice. My Hitachi ZX160 first of the 160's is overheating hydraulic oil, brand new hydraulic pumps, resealed control valve, new relief valve and cooler flushed, still overheating hydraulic oil can get to 100 degrees nearly and then that shoots the engine temp up, hydraulic oil gets dirty fast. Can someone give me step by step instructions of how and where I shut off or isolate pilot system to see if temp comes down please ?
posrepair2013
Well-Known Member
What do you mean hydraulic oil gets dirty what does it look like and does it smell different?
Huffa
Well-Known Member
Yea gets that brown dirty look fast and smells a bit burny, its just getting hammered running at 90 odd degrees constantly
posrepair2013
Well-Known Member
Burnt as in like gear oil? If so check and see if one of ur final drives if over full I have seen brake seal fail and then when final drive fills up it creates pressure and blows out case drain and that's what causes fluid to turn dark and smell
Huffa
Well-Known Member
Ok thanks for the input, will do
posrepair2013
Well-Known Member
Did you ever figure out issue?
Huffa
Well-Known Member
Hey not yet, have been away from machine but will check those final drive levels. If something was amiss there would it affect performance on some or all functions?
did you ever find out why the hydraulic oil was heating up??
Knivens894
Well-Known Member
On my machine, I am currently rewiring all the sensors and outputs of the hydraulic CPU. It kept eating sensors like candy. The old soaked wires, especially with heat and time, lose their elasticity, crack, and become faulty. I first determined the wiring was bad by disconnecting the CPU and using a meggar to test the wiring insulation. They all tested either marginal or bad. Faulty wiring means the signals each way are not valid, causing the machine to overheat hydraulically.
Huffa
Well-Known Member
Hey, no I did not, still gets hotter than what it should and causes engine to get hot
Knivens894
Well-Known Member
I have fought this identical problem for years, even to the point of installing an electric fan in front of the radiator on my 490E. I am now rewiring the hydraulic controls of the machine and will report on the results. Check the brittleness of the wiring. If they are cracked, I would recommend they be replaced before the machine is ruined by high temps.
thanks for getting back to me my Hitachi 120-3 still the same after 1hours hydraulic gets hot not sure where to start before this happened it would barely move the main boom up or down it would kill the engine so i changed the solenoids on hydraulic pump and it made it worse I think because they were cheap China solenoid not sure. took them off again and cleaned the old ones put them on and it worked away fine for a few hours. it was after when I put my hand under the exhaust box that I felt a small pin hole blowing down on top of the wires where it had them melted when I moved in a certain way the wires would connect together and cause the machine to kill the engine when I move the main boom arm that was my problem all the time just siad I'd say it it might help someone