OK. Now were getting somewhere. ... Unfortunately theres no development history we can access. I have a 2010 Gas so maybe it models yours closely. Why dont we experiment? :
,,,,Drain your coolant and save it.
,,,,Fill with water, but a little low. Cover the core about 1/2"
,,,,Cap it and start it up. Squeeze the top radiator hose and blip the throttle a few times from lo idle using the carb linkage. Does the coolant pressurize immediately and increase as you blip repeatedly?
,,,,Before it heats, remove the cap and look in while you play with rpm. Is the fluid flowing noticeably? Is it bubbling?
,,,,Continue as it warms toward midrange. Does it exhibit flow now? Does any bubbling stop or get worse?
,,,,Stop the engine. What happens?
,,,,When whatever stops, put the cap ON and start the engine. Blip for ~ 15 sec.
,,,,Stop and loosen the radiator cap with a rag. Was there any significant pressure buildup or barely a spit?
... These should tell us something in the course of just a few minutes. :confused3: