I live in Hawaii where outside temperatures range from 80-90 degrees. My 307 excavator has been running hot with coolant first, than hydraulics to follow shortly after. Thermostat is okay, and there is no coolant loss or leaks. Engine runs fine and only starts to go into red after about 1/2 hour of operation. Engine oil level is correct and all hydraulic and oil filters/screens have been changed with new engine oil, hydraulic oil and coolant. Machine doesn't get as hot if engine compartment door is left open. Coolant appears to be flowing on start up with no bubbling or pressure. I have also blown out oil cooler and radiator fins with compressed air. Does anyone have any ideas where I should be checking. My engine is a 4d32 mitsubishi.
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bobcat_ron
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I would be checking the thermostat heat it up with hot water and see what really happens, it might be sticky, you pretty much covered all the bases with the external things, the hydraulic cooling would be hot because it shares the same space as the engine cooling. Have you tightened the belts also?
thetool
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Pressure test the radiator cap?
Belt replaced and tightened, new radiator cap installed, but still gets hot.
Belt replaced and tightened, new radiator cap installed, but still gets hot.
thetool
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Well, you've got all the basics covered.
If you've got a variable displacement pump and it's not tuned correctly, this could cause overheating.
So could low engine compression.
Your radiator could have a restriction and need a douche job by a local radiator shop.
I've been exactly there with over heating problem children on Bobcats.
Good Luck
skidsteer.ca
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You need to sell it to me, -37c here this morning, like to see it over heat here!
Seriously though, if the thermostat does not cure it it may be time for a new rad or to have the rad rodded out (clean deposits on the inside of the cooling tubes), the latter of which is only a 1/2 fix. If opening the rear door, which must improve air flow seems to help , it indicates to me that the rad just isn't transfering the heat. You could try running a garden hose over it to see if that will bring the temps down, which again if that helps would point to new rad as opposed to thermostat. The only other thing you can do (aside from investigate the pumps overloading it by being out of adjustment) would be to improve the fan shrouding or change the fan size, or anything else that looks like it will make more air move through the rad.
How old is the machine?
Ken
