I recently have flushed my A-4 three times and have and added a new fresh water system but, the engine temperature guage indicates over-heating. The guage is also a recent replacement for the exact same type, model "stewart warner" only new. After last flushing I checked the temperature of the water at the fill cap of the heat exchanger. This is the water/antifreeze that goes through the engine. It read 170 degrees when the guage read 230. I am assuming the sender is not reading correctly. Any Idea? Secondly, I tried to remove the sender with the proper socket and rachet but not luck. Any Ideas how to free sender and get it out? It there some type of penitrating oil that really works or special tool?