1994 Honda Accord LX Overheating Intermittently

My '94 Honda Accord LX has 83,000 miles and has an overheating problem. I can drive it for 30-45 minutes and no problem. It will sit for 30 minutes to a couple of hours and then when I am on my return trip it overheats! I have had everything replaced - water pump and timing belt, radiator (just recently flushed again), thermostat, fans, alternator. Sometimes it will go just a little higher than the 1/2 way mark and other times to the line just before the red mark. I can also drive it for a day or so and no problems. So it doesn’t happen every time. My mechanic is at a loss since he can let it sit running for a long time and it doesn’t overheat. He even did that without the fans on. So is there some obscure thing that would make this happen. I know he thinks I’m nuts because it won’t overheat for him. I just think there is something about how it works ok and then after it has been off for a while, overheats. Any ideas? A person on a similar thread said that even though the indicator bar goes up as long as it isn’t in the red it is ok. Is that right? Doesn’t sound like it should do that. Thanks for any suggestions.

Do you need to add coolant to the car every now and then? I am thinking the head gasket may be starting to fail. Might be adding combustion gases into the coolant where it forms a bubble that causes thencar to get hot.

Red is bad. Getting close to red is an issue telling you to shut the car off.

No, I’ve never needed to add coolant. I have a few drops of something on the cardboard I keep under the car in the garage but it’s not a lot and takes a long time to accumulate.

Have your mechanic check the coolant for combustion gasses. There is a kit for this. Normally I’d suggest removing the cap from the coolant bottle and stsrt the car and watch for bubbles but it may be early enough in the path of a failing head gasket for that not to work.

Thanks for the help. I’ll ask him about checking the head gasket.