I am new to IH8MUD and love the content and help so far. I have a 1994 with 4.5l 1fz engine. It has been running a bit hot (half way between mid and red on gauge) when climbing hills only. Recently it started to jump up close to red. Even started doing it periodically on flat ground. Granted it is 115 here in Phoenix now. AC starts to go warm as the temp rises close to the red zone. Car cools down going down hill or even after I cycle the AC on and off a few times. Radiator pulls from the reservoir when hot, nearly empties it. I have drained radiator, replaced cap, replaced Thermostat. I see and detect no coolant leaks. Drained coolant was clean. I also did a combustion gas leak test and it was negative. Running idle in driveway doesn't overheat. Fans come on with and without AC. Coolant is flowing through upper and lower radiator hoses well. AC compressor doesn't appear to seem to seize when idle in driveway.
Needless to say I am stumped on what to check next. Any help or ideas will be appreciated.
Needless to say I am stumped on what to check next. Any help or ideas will be appreciated.