Replaced valve, car starts overheating - BUT only on motorway (3-4000rpm) and only when heater is not on full. Needle goes about 4/5s way up, not into or beyond red. Brought back under control by slowing down and putting heaters on full blast
Okay. Your prob makes some sense to me as it happens in the halfway position, im guessing the cold position too.?
If you're set to halfway, the instrument panel or "climate control panel" or whatever ford call it, sends pulses to the HCV, this opens and closes the valve repeatedly to give the right temperature. With the valve open the coolant obviously passes through the matrix and back out through the HCV and back to the engine. With it in the cold position it bypasses the matrix through the valve. If the valve isn't letting coolant bypass through, i would assume the restriction of flow through the cooling system would cause the overheating.
lot of peeps seem to think its caused by the Ford coolant. when it overheats it turns into a thick red sludge, which blocks everything up and overhearts even more. what causes it to overheat in the first place though im not sure.
Ford actually know about the problem and there is a technical bulliten issued with a list of 4 parts to remedy the problem, two of them are a revised larger bore water outlet and a bigger bore water pipe, not sure of the exact parts/locations but i will have the finnis codes by monday night with any luck
These parts do work!i had this problem a week after a broght my car, took it to ford they put they replaved my hcv with 98 part on it and it worked for afternoon, i took it back that day and said i was not happy, so they booked the car in to have another 98, as it some times solves it, i got a phone call and 2pm saying that it had not been fixed and they were ording some new parts that should solve it!! they fitted them 3 days later and my overheating prob was solved but they would not say what the parts were, all they told me was they were new water pipes, and another part to remove more heat from the engine.
I had the exact same conversation with the service dept at Allen Ford in Rugby. He said that ford had indeed issued a technical bulletin with loads of mods/ ideas to resolve the problem. He also said that it was between me and him...work it out for yourselves.