Is my thermostat the cause for my 96 Honda ACCORD V6 2.7L ocassionally overheating?

Question

About three weeks ago on the highway the temp. gauge red lined on my 96 Accord V6 2.7L (with 200,000 miles). I pulled over/saw steam from the resivoir tank. After cool down, I filled it with 50/50 antifreeze & drove home with the heat on high. I checked for leaks with the heat on & did not find any. I have since been keeping a close eye on the temp gauge; which has run at the normal temp line & the fluid level in the resivoir tank has not shown any fluid level loss/leaks either. The car has been running normal since then until 3 days ago when the same thing happend again on the highway at 75/80 mph; I watched the temp gauge gradually rise to near red line, so I slowed to 60/65 mph & it began to drop back down to just past 1/2 way. Five minutes later after arriving home I checked the resivoir tank which was bubbling/slightly leaking over. With the car off I let the fan run & watched bubbling fluid syphon back over to the radiator from the resivoir until it was empty. I refilled the resivoir and the car is fine again. This ONLY happens when I'm on the highway at 75+ mph. Does this sound like a stuck thermostat issue?

Answer 1

You keep over heating it your going to warp the head very very quickly. Find the problem. Replace the thermostat, also think about replacing the water pump, and the timing belt and flush the system. Hopefully you haven't warped the head by now. You probably already did it only takes a few minutes.

Answer 2

Well, the 'stat is a cheap replacement. I'd switch it before trying anything else.

Whilst you have the system open for that flush it through (bottom to top) with 200k miles (terrific!!) it may be a little clogged up.