Water pump ???? Also try replaceing the rad cap I find the caps made by STANT work the best on hondas.Hope this helps

 

105,000. I don't think it's ever been replaced. We can't find a leak coming out of it.

 

I doubt it's the water pump.

Does the engine have a slight miss/rough idle when you first start the car in the morning?

Head gasket failures are common in 7th gen's and diagnosing them gives people fits because the common symptoms (oil/coolant mixed, white smoke, constant overheating, low cylinder pressure) don't usually show up. It's just a pin hole sized leak, at first it will close up when the motor gets warm, that's why there isn't severe coolant lost. The problem is when you start it with the motor cold air gets in the system and the first place it seems to get suck is the heater core, air in the system also causes overheating.

I would try bleeding the system first. Park the car on an incline so the radiator is the high point, pull off the radiator cap (with engine cold), start it up and look for air bubbles coming out of the radiator. It helps to give it some revs every min or so and watch the temp, give it 15-20 min. Make sure the radiator is full and put the cap back on and take it for a drive and see if you have heat at idle.

Have you looked at the spark plugs? If it's been leaking for awhile there may be residue on one of the plugs.

 

Runs like a champ - engine sounds great. By bleeding you mean flushing the system, right? I'll take a look at the spark plugs.

BTW, airmanjason, I've replaced the radiator cap twice - wasn't sealing properly. Are you in the USAF? My son is in basic in San Antonio now.

Also, the fans are working properly.