Time to change that thermostat. This is a easy job and takes 10 to 15 minuets.
First, make sure your engine is cold. Then twist your radiator cap one click to remove any pressure that might be there.
Best to use a hose clamp remover, other ways are not really safe. This is a pliers with a cable
Once clamp is locked open you can wiggle the hose off the housing. Have something to catch the fluid, not much will come out.
Now place the rubber ring on the new thermostat
Then place it back in the LIM.
Now bolt the housing back down and torque and place the hose back on.
Remove the clamp tool and your done. You may need to add a little coolant to the overflow tank. You may need to open the bleeder valve to remove any trapped air.