Hi guys, new member and new to the Toyota van community. I recently purchased a 88 4x4 le and am in love with it. Previous owner had put in a new engine about 10k miles ago...which brings me to th issue. I've been driving it for about a month with zero issues. Runs and sounds awesome and the temp gauge hovers a little below 50% up to 45-50 mph. Today I took it out towards Walden and was driving around 65-70 for about 10 miles and then my temp gauge went to the no-no red zone. Pulled over immediately and looked at the engine. Coolant overflow was boiling over and shooting out the bottom. This makes me think head gasket? Obviously that's worse case scenario and it seems strange I'd be having a head gasket problem with a new engine...I do have The service records for van and I'm suspecting that when they replaced the thermostat it was not a Toyota one. If it's a t stat problem would I be having the crazy overflow issue?Just want to know where to start looking before I send it to a mechanic for a head gasket. Thanks!