yanmar 1500 getting hot

[spiter23]

I have had a Yanmar 1500 for about 8 to 10 years. Never had any problem until summer before last. The idiot (hot) light started coming on- it does not come on when I use it during the winter. I have tried running straight water in the radiator, and have also tried running a product by pro-line called "ice water" that is supposed to reduce operating temp by as much as 28 degrees. Still the light comes on after the tractor has run for about 30 minutes. Have replaced the radiator cap and overflow bottle (had a small hole in the bottle). I don't know what else to try.
Does anyone know what temp the idiot light comes on ? If I replace it with a guage, where can I get one that will be easy to install? What is the normal operating temperature for this tractor ?
When the hot light comes on, the radiator is not boiling over, so maybe the tractor is not really hot? Could the sending unit be bad? It looks as if the radiator may have a couple of small cracks on the back side of it up close to the neck, but I never see any liquid or steam coming out. Need help. Thanks

 

[Tractors4u]

What kind of condition is the inside of the radiator? Does it need cleaning?

 

[normde2001]

Change the sending unit and clean the radiator, inside and out, problem solved.

 

[spiter23]

I will check that. Seems like it was pretty rusty last time I looked at the inside. Thanks for the advice

 

[spiter23]

Thanks Norm, I'll give it a try

 

[SailorBob]

The temp sensor went bad on my 1700. It would come on after running about 10 minutes and would stay on for an hour or so after I shut down the engine. Replaced idiot light with a guage. It runs about 190 degrees under heavy workload. I also had my radiator cleaned at a radiator shop. It cost $50 but, worth the piece of mind. Don't forget to clean the screen in front of the radiator

 

[MarkStewart]

Don't forget to mix your coolant 70%water to 30%anti-freeze if you haven't already. I think that model is thermo-syphon cooling.(No water pump) It will not cool correctly if the ratio has too much anti freeze. I'm not sure where you are located, but you may need to add antifreeze for winter etc. so it don't freeze up.

 

[thingy]

Try,,,BLOWING out your raditiator,,,with air,,,use one of those long air guns,,with about a 150 lb air compressor[course120,,100 would work just as good],,blow from back,,than front,,than back,,etc,,,,,than flush drain and flush your raditiator,,and fill back up with a 50/50 mix,,Also check your fan pully belt,,,I bet if you do all that,,and light still comes on,,it is nothing to worry about,,,ALTHOUGH,,could be the thermostat,,,,,thingy

 

[mark777]

Just FYI: The viscosity of 50% anti-freeze and 50% water is not recommended for Yanmar tractors. As the previous poster suggested 70% water and 30% anti-freeze is the correct ratio.

Mark

 

[thingy]

Well,,that maybe well and good,,,,,,as long as you don't go below the freezing point for that 70-30 mix,,,after all,,thats the main reason for using anti freeze,,,is to anti freeze protect it,,,right? thingy