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my temperature light comes on after about 45 minutes of mowing. I just got the mower with 1060 hours on it. i changed oil using Rotella 15/40. the antifreeze looks OK but i haven't checked the potency. Any suggestions?

You should also blow out your radiator if you have not already done do. I'm not familiar with them (Yanmar) but my old Kubota tractor basically had a wimpy radiator. It has a screen on the intake side that needs to be cleaned regularly or it will overheat, even with fresh coolant. I clean the screen after every use and blow the radiator out regularly depending on conditions. The tractor is about 40 years old and still runs pretty good. I think the radiator is undersized although if clean it works just fine.

Once you checked all that I suspect you might want to look into the thermostat and/or the water pump.

Your first thing to check is the coolant temperature to make sure if its a engine problem or gage problem.

Also check the radiator cap, if it doesn't hold pressure it will also allow the engine to over heat.

RhettWS said:

You should also blow out your radiator if you have not already done do. I'm not familiar with them (Yanmar) but my old Kubota tractor basically had a wimpy radiator. It has a screen on the intake side that needs to be cleaned regularly or it will overheat, even with fresh coolant. I clean the screen after every use and blow the radiator out regularly depending on conditions. The tractor is about 40 years old and still runs pretty good. I think the radiator is undersized although if clean it works just fine.

Once you checked all that I suspect you might want to look into the thermostat and/or the water pump.

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thanx, I should have thought of that first

let us know what you find. best of luck!

http://www.wfmfiles.com/download/manuals/TM1591.pdf

see troubleshooting guide page 220-10-4, G overheating

http://www.wfmfiles.com/download/manuals/CTM3.pdf

Glyn Robinson said:

let us know what you find. best of luck!

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I think in needs a flush. It looks like a build up around the tubes in the radiator.

maybe that will help. certainly won't hurt.

mechanic mark said:

http://www.wfmfiles.com/download/manuals/TM1591.pdf

see troubleshooting guide page 220-10-4, G overheating

http://www.wfmfiles.com/download/manuals/CTM3.pdf

Click to expand...

Thanks ! This is great information.
My John Deere 332 with Yanmar 3TN66UJ engine is running hot so intend to give it a work over this winter I need it one more mow. (it's out of state) The water pump doesn't leak though and I have found that the replacements are rare to find- Not even sure that is the problem .
I need to flush the radiator first (see some corrosion) I think, so will start there. The temperature light comes on and stays on from the turn of the key so must be grounded some where do you think? I know it's hot though because it pukes a small amount of antifreeze out after a 30 min mow.
Thanks for opinions.