ZD21 overheating (21 HP diesel)

[lawnmover]

Aloha all, My ZD21 mower is overheating. I had a bunch of grass in the radiator fins and it overheated. I blew out all the grass, let it cool down. Now it overheats almost immediately.
I'm trying to isolate and discover the problem.

The radiator gets hot on the top, including the hose, but the lower portion is dead cold.

Hopefully I didn't blow a head gasket??

Any thoughts here?? How can I tell if it's the water pump? I replaced the thermostat a few months ago.

Thanks!

Chris from Maui

 

[yelbike]

Did you check the coolant Level? Sometimes when they overheat they blow off a little coolant.

 

[art]

You antifreeze is not moving. Start the engine when cool with the cap off and see if it moving your coolant. Your hottest coolant would be on the top of the radiator after the thermostat opens.