B7800 heating issues

[quadcent]

Hello all, I have a B7800 that will run great 5 times, then all of a sudden will over heat the radiator. Sometimes right away just sitting idling first start up, next time after being used for an hour rototilling.

Have changed thermostat, blown and this time washed out, removed water pump to make sure impeller is tight, but can't seem to see why it's hit and miss with the over heating, and not always when working it

 

[Bee-Positive]

Not quite clear on what "blown and washed out" means.
Radiator cleaned?
Air filter cleaned?
Hydraulic strainer cleaned?
Hydraulic fluid level good?

"...to see why it's hit and miss with the over heating."
Electrical connections not corroded? If you have access to an infrared thermometer check the engine/radiator temps to see if the gage/connection or sending unit is bad.

 

[Sawdust&Shavings]

Hello all, I have a B7800 that will run great 5 times, then all of a sudden will over heat the radiator. Sometimes right away just sitting idling first start up, next time after being used for an hour rototilling.

Have changed thermostat, blown and this time washed out, removed water pump to make sure impeller is tight, but can't seem to see why it's hit and miss with the over heating, and not always when working it

Like Bee-Positive said, an infrared thermometer is your friend; part of your early investigation needs to establish that you are (or not) actually over heating…if you are over heating your next step is different than if you are not over heating,

 

[85Hokie]

I spent an hour cleaning a radiator the other day, an abused machine that NO ONE gives a @#$%#$% about. I thought I did a good job cleaning it too...... not so fast my friend - I PULLED it out and held up to the sunlight - my cleaning was "good" up till that point - took a low end pressure washer and cleaned the fins over and over and over. The bottom was awful .......... back on and now engine runs well and does not even get to the red - not even half way..

I am a huge believer of the infrared thermometer - even if off 2% it still tells great story when trying to id a cooling problem.

By the way - the bottom reading on a "good" radiator should be 80+ degrees less than the top of radiator.

 

[jaxs]

What Hokie said and I might add. If you are unable to pull out and hold up to light,do it at night or in dark shop using flashlight and mirror to check BETWEEN fins. Adding laundry or dishwashing soap can't hurt and often cuts stubborn oil or grease holding dust in fins.