This was a very helpful thread to our Kubota B3030 that has been overheating (bottom of red zone before shutting off to protect the engine) for at least 7 years while mowing 5 acres.
We have been through every scenario listed here, replaced belts, thermostats, anti freeze, flushed, radiator caps, on and on. Still get to the bottom of the red while mowing.
I did the radiator temp test at the top and bottom of the inlet and outlet 216 degrees at top and bottom. now I was just totally puzzled. Water pump? Clogged internal coils?
LONG story short, he has told me so many times that he has used coil cleaner and hosed out the condenser and radiator yearly (another problem we just ignored was AC not working after the tractor warmed up to HIGH in the New England summers).
THE FINAL FIX: Although the condenser and radiator looked great, I decided to do the cleaning myself. I followed the instructions, sprayed the stuff on, waited 10 minutes and hosed off (he said that is what he did, only once each attempt.)
I did it once with the hose and saw a lot of discolored water and grass dust etc. (but visually it looked perfect) So, I did it again but was concerned that I could not get behind the condenser which eats up 3/4 of the radiator area ... so I got out my (2000psi) pressure washer on a 40 degree nozzle and spent a lot of time cleaning front to back and BACK to FORWARD through the shroud and fan fins. Did this for at least 30 minutes using the coil cleaner 3 times.
RESULT: Tractor runs like brand new. Temp gets to a 1/4 of an inch over cold instead of 3/4 into the bottom of the RED and the AC is ICE COLD all day. ;-) Such a simple but elusive fix!!!!
I hope this helps someone else!
