First thing that happened, A/C compressor seized, serpentine belt snapped, car overheated, reservoir hose popped off and sprayed steaming coolant all over my hood on the side of 95 on my way to the train station for a business trip.

I got an A/C delete belt and refilled the coolant, kept going. Nothing seemed wrong.

The car would occasionally hit 4 bars and lose heat, coolant was disappearing.

I kept refilling it, and refilling it. One day I noticed steam coming rom below my radiator. So I replaced it with a Mishitomo one, it was running great all weekend, never went above three bars, tonight it went to 6. There was what seemed like stuff that came out of the cap. I don't have heat either right now. The hose coming from the engine to the radiator is hot, the hose going from the radiator to the motor is ice cold.

Do I need to replace my water pump now? Thermostat? I thought I successfully burped the motor.

 

Pretty sure you have an air pocket in the system, keep burping the system it can take a few times to get all the air out. I hope it isn't too late though , 6 bars could be enough to have warped the head already. Check to see that the water pump turns smoothly, the only other thing would be a thermostat stuck closed. Definitely start by doing additional bleed sequences. Are you getting very hot air coming out of the vents with the heater on ?, if not that is a sign of air in the system and you need to keep bleeding until you get consistent heat.

 

Yep. Sounds like an air pocket. Try to bleed the system again.

 

I just did, I ran it until three bars. No heat, nothing came out of the valve by the intake manifold either. The water pump pulley spins effortlessly, so I'm guess thermostat stuck closed? I ordered a spoon one tonight. Hopefully it'll be here this weekend.

 

the heater core in the S2000 is high compared to other Honda cars, it makes it more difficult to bleed out. Try to keep the car at a high angle so that the air in the heater core(under dash) is lower than the top of the radiator. Afer you think all of the air is out of the system, Put the heater on in the car. It should get hot once the car begins to warm up and the heat should be VERY hot, not slightly hot. If it is not REALLY hot you still have air in the system

When I say the heater core is higher than other models , i mean in comparison to the radiater