I wrote up something on my temperature gauge one time. It yours is similar, I would be concerned about 1/8" from the hot mark.
http://www.tractorbynet.com/forums/...63-pressure-testing-bx2200-3.html#post1588614
The temp sensor on the
BX1850 is just above the exhaust. My
BX24 never went past the halfway mark even with the 60 inch MMM. The needle on
BX1850's temp gauge from new went to nearly touching the red on hot days with the 54 inch MMM and for some people went into the red. There was an answer on the Kubota site "OrangeTractortalk" from a Kubota service rep. I shot the hottest spot on the block I could find with an IR thermometer, with the needle nearly in the red and it registered 217 degrees, which is normal.
This is the service guy's answer on the Kubota site:
"Originally Posted by Service Dept Vic View Post
Anyone that owns a
BX1850 has the same issue because the sender is located ontop of the muffler!
I'd recommend putting an actual guage on that engine to ensure it's not really overheating, which it probably isn't, but it's a good measure of safety!
Try to shield the location where you attach the guage when you're doing this test (same spot as current temp sender) with a large ceramic tile, asbestos sheet, or some other non heat conducting product so you can get an accurate true temperature reading on the engine.
If the temp is normal, and it probably is, take a look on the engine for a different location that will accept a new sender unit.
If you can't find one, remove the radiator and take it to a rad shop and have them solder in a threaded port to accept your sender unit. make sure to take them the new sender so they can match the metric threading required to accept you sender.
Have them locate that port in a location that is FAR away from the horizontal under hood muffler system that you have now.
Install new 50/50 coolant, replace the rad cap, adjust the fan belt tension, extend the length of the wiring to reach the location of your new sender, and you're done. Leave the old sender inplace on the cylinder head as a "water plug".
An hour or two of your time and $100 bucks at the rad shop and Bob's your Uncle!! "