my temp. keeps rising from180 to 230 holds there for awhile then falls back to 180 . I recently replaced my water pump with a flow kooler pump ,new therm. housing .new robertson stat. new radiator cap ,new hoses flushed radiator . thought it was air locked . ive blead the heater coil and lines. still doing it .it not red lineing . this happens at speeds of 55 to70. any ideas?
Your thermostat is stuck closed. When it hits 230, the pressure blows the thermostat open then it cools and starts over again.
