Overheating problem

Hey guys i have an M13A non vvt engine 2002 jimny and lately i noticed that the radiator most of the times is empty and all the coolant goes to the overflow tank and stays there . My temperatures were okay but yesterday in the i did 1hour trip in the highway the temperatures were okay and when i got in the city center the temperatures started to rise.. Btw i dont have a thermostat in the car .So i checked the engine and i found that the freeze plug on the engine was leaking coolant but just a little bit . Is this the problem that cause the overheat and the empty radiator ? 

If it's displaced the coolant to the reservoir and the temperature gauge has shown hot then you will almost certainly need a new head gasket/head crack tested. It's entirely possible that the leak shown could have been a major contribution to the initial over heating.

Having just read this I am starting to feel like Phil Connors, time to check on Punxsutawney Phil.
Carry on chaps, see you all at 6:00

Check the viscous fan.

Get a rolled up newspaper and get the engine properly hot. Paying attention to not losing your fingers, push the paper into the fan. If the fan stops then the hub is stuffed, if the paper is shredded then the hub is fine

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In addition: If the radiator is empty and the coolant „moves“ to the overflow tank, then also the radiator cap might be damaged. When the engine gets warm and the coolant expands, the radiator cap should allow some overpressure and then open and discharge the excess coolant into the overflow tank. When then the engine is switched off and gets cooler, then the coolant contracts and the radiator cap should allow the coolant to be sucked back into the radiator.

If the head gasket is damaged, there might be an over pressure in the cooling system and this would lead to a discharge of the coolant into the overflow tank without thermal expansion of the coolant and then also there would be no sucking back of the coolant.

What was the reason for removing the thermostat?

I only ask as many years ago my thermostat was sticking, so I removed it and in a 25 mile journey at this time of the year the car temperature never rose above cold.