Power gone? Add coolant, now back?

[Webber]

Hello TBN readers. I have an L48 kubota. I experienced my tractor dropping to near zero in power. It only happened after it warmed up. Thought it was fuel so I did all the checks, not fuel. Maybe head gasket, did pressure check, not that. My coolant was low? Not over heating so did not think much of it.
Two temp sensors, one to dash gauge the other to????
Long story short, I added coolant when testing for gasket and it never acted up again?
The second sensor goes where and does what? Can anyone tell me how this could occur?

Thanks, just need to know.

 

[Deano]

Does not make sense that it would be from the coolant being low. If it was critically low and overheating, ok would make sense.
What do you mean "Thought it was fuel so I did all the checks"?
Still sounds like a fuel filter with crap in it, or the fuel tank not vent not working properly.

 

[Webber]

I asked around and a diesel bus mechanic said it is most likely fuel? I checked all lines, changed the filter, changed the lift pump, blead it many times. Still acted up. Put an exterior tank on it and a seperate filter, same act up. Gauge said not overheating. Coolant tank was empty but radiator was full? Studied all the fuel and electrical schematics I could get and nothing made sense. Got to the point of calling a Kubota Mechanic who said, if all that was done, it could be a head gasket? The tractor was 20 miles out in the woods so doing all these things became an issue. Finally, I towed it in town and when I did the head gasket test I added coolant. That was the only thing done and it ran great ever sense?

The mechanic who helped me said two things---1. We re-blead the fuel lines for the tenth time and ran it with the air valve open for a long time. Could this have been a problem that when warm an air bubble expanded and caused this? I blead it and more many times and ran it for hours afterwards but it would act up everytime it began to get warm. 2. That second thermo sensor may have not been submerged due to low coolant and if that has some way of stopping or ideling the engine than maybe but we could not see any way of controling the engine but for the fuel cut off soleniod and we took that out during the testing.

What was this? Still no idea.