My coworker friend's 92 4runner 3.0 just overheated this morning warming up b4 heading out the door.

We turned engine on for a few mins, then i heard the idle dropped to normal. I went in to turn on the hot defrost, but there was no heat coming out from the fan air the whole time we were scrapping ice off the windsheild. She went in again 2 mins later, seeing that the temp needle was at max hot! So we shut it right away.

Not knowing much about 3.0, I'm guess it's either stuck thermostat or maybe commonly known blown headgasket ? Expansion tank was filled w/ coolant to max during the process too.

ps, tomorrow i will check the coolant & oil.

Any suggestion?

I was thinking about the cjm's taco engine conversion today. If it's a blown headgasket, would it be worth-while to put in 1 of those engine vs fixing the headgasket? it's a mint 92 4runner w/ almost no rust, would be a shame to junk it...