Where is coolant going? Not leaking out. Not in oil. Gets hot 1x a month, need.. on 2001 Toyota Tacoma

to add coolant about 1/2 gal. then ok for a while... plz advise???

Asked by for the 2001 Toyota Tacoma
1 answer
poss headgasket leaking thru combustion chamber and out the exhaust. have a chemical test done and compression test