on hot water heat with a boiler you should pressurize the system then open the bleeders
thermostat or air in clling system replace thermostat and bleed the system
look for bleed plug on thermostat housing or run car with radiator cap off in park with hosepipe in radiator till bubbles are gone.
Follow the upper radiator hose to the engine. It is clamped onto the thermostat cover. There should be a coolant bleed screw just above it. 3.1L engine.
On top of the thermostat housing is a bleed valve. Loosen the top nut first, this will bleed it. There is another one on the radiator, but I haven't found it yet.
It probley has an AIR pocket in the cooling system. Bleed the air out of the system and make sure it is full of fluid.
follow the top radiator hose to the engine, where it connects is the thermostat housing, inside there is the thermostat. If you replace the thermostat, be very careful to install it with the air bleed hole in the proper position, and be sure to get as much air as you can out of the water jacket before you seal the system back up. Bleed the system well when you check for leaks.
The thermostat is in the radiator. Open the radiator lid and pull the thermostat out.
If there is not bleed valve for the coolant you will have to do it manually. Fill the radiator up and start the car. After it warms up the coolant level will drop, refill it.
Follow the lower coolant hose from the radiator to the engine block. The housing where it attaches should hold the thermostat. Make sure you insert a new thermostat with the bleed nipple on the top.
The cooling system is bled using the bleeder screw found on the thermostat housing. To find the thermostat housing on a 1998 Honda Civic follow the lower radiator hose to its outlet. While the cooling system is running loosen the bleed valve. When bubbles stop coming out the system has been bled.
Cooling fan not working? Thermostat not opening? Plugged radiator? Water pump not working? Defective radiator cap? you have to bleed the thermostat
You don't fix it you replace it. Drain the radiator, replace the hose, and the thermostat, flush the system, install a 50/50 mixture of antifreeze and water, bleed the system.