Have been watching this forum which has given some great info so here's one I need help with- a little Hitachi ex40-2 that's heating after about 20 minutes work. Kubota engine, Radiator has been replaced with new one, new coolant, thermostat removed. Water pump is circulating fine it seems and new fan belt with proper tension. The engine is started and when warmed up can be put on full throttle without working the machine,and water temp gauge will eventually rise to just under halfway and stay there. The issue is when the machine is worked, tracking/digging using the dipper that after about 15-20 minutes the water temp gauge rises and will climb to just under the red line, I have never let it boil. If the bonnet is lifted while the machine is working it stays cooler for longer,if it is worked hard though even with bonnet open it will eventually heat. I have checked the under bonnet temperatures with infra red thermometer after it has been worked for approx 30 minutes and heat has risen,and the max temperatures I am getting are around 75 degrees celsius at the radiator cap and on the top of the oil cooler. I have checked the cooler and cleaned it, hydraulic filter in the tank has been replaced. New ISO 46 oil is being used. I notice also that when I stop working the hydraulics when water temperature is up,the water temp will eventually start dropping. So this is indicating to me an issue with hydraulics heating, causing the oil cooler to heat and in turn the water temperature heating. Any advice on what to do or where to go about remedying the issue? Thanks
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EX40-2 Hydraulics heating
- Thread starter Pat-M
- Start date
There is no digital measurement on the dash of the machine to tell what temp it's at the gauge,it's a simple gauge with hand which rises and falls when the machine is running. What way could I check the gauge temperature in that case?
Nige
Senior Member
Can you find where the hydraulic oil temperature sensor is located and use your I-R gun to take the temp at that point.
75 DegC isn't even fully warm. An engine up to normal working temperature should run at anywhere from low 80's to low 90's depending on what the thermostat setting is.
Thanks @Nige I will do that with IR gun and see how I get on. If it's the case that the temperatures are staying around the figures I am getting so far it's the machine is perfectly safe to operate at those temperatures,and it may be a case that there may be a fault with the temperature gauge in the machine?
Nige
Senior Member
Post back what temperature you are measuring right where the hydraulic oil temp sensor is located.
Then compare the hyd temp with a reading on the thermostat housing or wherever the engine coolant temp sensor is located. It would not be unusual for the hyd oil temp to be a few degrees higher than the engine coolant.
You could have a defective hyd temp sensor, a defective gauge, or maybe even a wiring fault.
Then compare the hyd temp with a reading on the thermostat housing or wherever the engine coolant temp sensor is located. It would not be unusual for the hyd oil temp to be a few degrees higher than the engine coolant.
You could have a defective hyd temp sensor, a defective gauge, or maybe even a wiring fault.
uffex
Senior Member
Good day
This may be of interest
46 Hydraulic oil working temperature
30°C= 86.0°F Low
35>80°C = 95>176°F Medium
80>110°C = 176>230°F High
110°C+ = 230°F very High
Often overlooked is that of air flow with the correct tools you can measure, a missing or damaged shroud can have an adverse effect. Working in confined areas can also have a negative effect, which is the curse of small excavators. Some manufacturers offer a "Tropical" fan to reduce the heat.
Kind regards
Uffex
This may be of interest
46 Hydraulic oil working temperature
30°C= 86.0°F Low
35>80°C = 95>176°F Medium
80>110°C = 176>230°F High
110°C+ = 230°F very High
Often overlooked is that of air flow with the correct tools you can measure, a missing or damaged shroud can have an adverse effect. Working in confined areas can also have a negative effect, which is the curse of small excavators. Some manufacturers offer a "Tropical" fan to reduce the heat.
Kind regards
Uffex
Getting back to ye on this @Nige @uffex ,had it working for a good half hour today.the water temperature gauge rose to approx three quarters of full. The water temperature buzzer sounded and light came on on the dash. I checked the temperature with the IR gun at the thermostat housing where the temperature switch is located. It was reading 110° celcius. I checked the oil cooler temperature where the pipes enter and exit the oil cooler,this was running about 75-80° celcius. I've yet to check the temperature at the hydraulic oil temperature sensor,I have to locate it and check it out.
Last edited:
Nige
Senior Member
I wouldn't class Ireland's climate as "tropical" in any sense of the word.......
Still don't like the idea of removing the thermostat. If there was no need for one the manufacturer would not have put one there in the first place.
I can put in a new thermostat to see how it reacts with that or if it makes a difference. The thermostat is removed at the moment and working without it.
After approx 15 minutes light work this morning,the gauge was at approx 3/4s,water temp buzzer started to sound,checked it at the thermostat housing with IR gun it was reading 105° celcius there, reading 80° celcius on top of the radiator at the cap while the temp at the hydraulic oil sensor was reading approx 69-70° celcius.
After approx 15 minutes light work this morning,the gauge was at approx 3/4s,water temp buzzer started to sound,checked it at the thermostat housing with IR gun it was reading 105° celcius there, reading 80° celcius on top of the radiator at the cap while the temp at the hydraulic oil sensor was reading approx 69-70° celcius.
Nige
Senior Member
That makes no sense. The thermostat outlet and the radiator inlet should be pretty much the same temperature. Is the coolant flowing at all.? My next thought would be check the water pump.
uffex
Senior Member
Good day
I guess I should have explained my comment as a possible solution which should only be considered providing the core of the coolers are clean, air cleaner & thermostat is serviceable and recommended cooling fluids used.
In case of doubt, flush the system and use the recommended mix of coolant solutions. Modern cooling fluids have a superior cooling capacity compared with water.
Another possible solution would be a smaller fan drive pulley. The post infers that the cooling is an issue with both engine and hydraulics, however a hot engine cooler may have an adverse effect on the hydraulics or vice versa depending on if the fan is a blowing or suction type.
Attached is what information I have in respect of the engine in the subject machine. I trust this maybe seen as helpful.
Kind regards
Uffex
I guess I should have explained my comment as a possible solution which should only be considered providing the core of the coolers are clean, air cleaner & thermostat is serviceable and recommended cooling fluids used.
In case of doubt, flush the system and use the recommended mix of coolant solutions. Modern cooling fluids have a superior cooling capacity compared with water.
Another possible solution would be a smaller fan drive pulley. The post infers that the cooling is an issue with both engine and hydraulics, however a hot engine cooler may have an adverse effect on the hydraulics or vice versa depending on if the fan is a blowing or suction type.
Attached is what information I have in respect of the engine in the subject machine. I trust this maybe seen as helpful.
Kind regards
Uffex
BigWrench55
Senior Member
Some engines will bypass the radiator if the thermostat is removed. Not sure this applies to your engine. Just wanted to share that information.
Checked the water pump out,impellars and shaft perfect. Seems to be operating fine. Should I bypass the output/input to heater and see if that makes a difference? Have looked at the potential issue coming from the head, it's not building pressure or leaking into the cooling system.
Nige
Senior Member
Did you refit the thermostat yet.? See BW55's post above.
Fully functioning thermostat refitted along with the water pump,new coolant also. Pipes to cab heater bypassed also in case there may have been a blockage or restriction causing an issue. No difference, heating exactly the same,after about 10 minutes or so of light work the temp alarm is sounding and gauge high. Temp at thermostat housing 110° celcius+, 90° on top of rad,mid 80's on hydraulics. I checked for any restrictions in the radiator and flushed from top of thermostat when water pump was off,all seems to be flowing freely without restriction.
So folks,just to update-still having issues with overheating of the engine Thermostat,water pump were checked and fully operational, working fine. new radiator, which has been flushed and checked, the head was taken off, pressure tested,skimmed and new head gasket put on. The heater is working fine in the cab and system flowing freely through it. The very same symptoms as pre head gasket change, overheating after 10 minutes work. An excavator mechanic had a check of the hydraulics,and believes them to be working fine with no excess heat being produced through a sticking valve or the likes. I would think maybe it's time to move onto another project.
excavator
Senior Member
There should be foam pieces fitted around the radiator that forces all the fan air to go through the radiator instead of around it. Check to make sure that they are all properly fitted. Even while running with the hood up it will make a difference.