Tb125 overheating issue

06 area tb125 4400 hours problem with overheating have flushed radiator fins are clean oil cooler clean have the thermostat pulled and it will get near the red after light use rpm doesn’t seem to affect it seems to be hydraulic functions like tracking that heat it up the fastest

Have also changed the radiator cap as well

Have you checked fan belt tension when the machine is hot? It could also be a worn/faulty water pump (assuming you're using a good quality coolant). The oil cooler could be clogged too or providing restricted flow. Have you changed the oil cooler filter? I believe there is a a way to test oil cooler flow. That info may be in your service manual. I've also worked on a job with a harvester that was overheating. It turns out that low quality hydraulic oil (actually low viscosity oil was in the machine for extremely cold weather) was the source which caused the system to overwork and heat up quickly (in hot weather). Not sure we have that issue with excavators. That said, tracking is a demanding task on the hydraulic system. While it wouldn't be the first thing I'd check sometimes the simple stuff is the problem. I live in California so no extremely cold weather here.

Fan belt is tight checked coolant gasses with head gasket tester and no exhaust fumes present

With it in the red on the gauge only showing 210-217 at the thermostat housing at the hottest radiator is far cooler could it be a faulty temp sensor and is there a way to test it

On my TB53FR, changing from the 110mm pulley (Y129403-42380) to a 95mm, on the water pump, seemed to cure the hot running.

eadams1998 said:

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Very cool diagnostics. Maybe you could run that infrared on the intake hose on the top and lower hose on the bottom and see if there is a drastic heat difference--which then might point to a water pump issue. These sensors, I believe, are thermistors (meaning the ohms resistance drops as the engine heats up). Your shop manual will have a procedure for checking to see if the sensor is getting 1) voltage (so no broken wires and likely just pull the leads, turn the key on and test DC voltage), and 2) I think you can test the sensor on the engine by disconnecting the leads and connecting your ohm meter to it. As the engine heats up the ohms resistance should drop. I don't know the acceptable parameters for the reading. I've done this on cars but not excavators. Wondering if you have a plugged or restricted hydraulic oil filter somewhere that maybe be caused the unit to overheat quickly? Also, thought heymccall's idea was clever if all else fails.

upper hose is 180 area and lower hose is 150 area and Neither the radiator nor hyd cooler show any hot spots or hot temps both cool enough to hold a hand to them

eadams1998 said:

upper hose is 180 area and lower hose is 150 area and Neither the radiator nor hyd cooler show any hot spots or hot temps both cool enough to hold a hand to them

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That temp difference is far too high. Even on an optimum system it shouldn’t be much more than half that. Indicates low coolant flow for some reason. Internally plugged radiator, water pump….??

Try reinstalling the stat and see what happens to the radiator inlet/outlet temps.

Make sure the valve is open for the heater and the lines have all been burped.