my motor has been overheating at high rpm,s I just pulled my water pressure relief valve and it was stuck,I had to pull it out with pliers,I,m assuming it should not be that way ?and what is the best wat to clean the corrosion off?also the thermostat had what appeared to be a blown rubber gasket and was extreemly stiff in movement my question is there was only one thermostat on the left side cylinderhead the other cylinderhead did not have one and the right side is the one with the sensor should it also have a thermostat? this motor was rebuilt 3yrs ago and I,m beginning to have my doubts,this particular model has the water pressure relief valve located on the bottom of the exaust cover under the bypass cover it is not located under the thermostat cover. also any other advice on overheating would be appreciated thanks Gus