Bought this '99 for my wife as a dependable driver and now I'm having trouble. No one can seem to tell me what's wrong for sure, even Honda. I'll try to describe the problem as best I can.

Car can sit at idle in 100 degree heat with the a/c on and never overheat. If you drive it after about 50 miles or so it will start to heat up. You can pull over and let it run and it will actually cool off. It only seems to heat up when the engine is running at 3000 rpm or more. Changed the rad cap and thermostat with OEM. I can hear the overflow tank bubble when the car heats up good and hot. Overflow tank will fill up but will go back in rad when it cools down like it should. I did notice yesterday that I had some coolant leaking from the overflow. Not sure where it came from. Had to come from the top. The rad must have pushed too much out. The hoses do not seem to have a lot of pressure on them when heated up. This has me at my wits end, hope someone can help. Thanks.

 

Welcome new member!

You've already done what I would have started with - radiator cap & thermostat.

Lots of liquid going into the overflow reservoir suggests a bad headgasket. Bubbles in that reservoir suggest combustion gas, since actual boiling is not likely in that plastic tank. The steam would collapse to liquid before it got thru that little rubber hose.

But the hoses NOT being pressurized doesn't fit with a bad headgasket. So back to the radiator cap. It's new, but it relies on a proper seal against the neck of the radiator, so take off the cap & check it out. Scratches around the very top of the radiator neck would leak out right there. But just below the overflow tube, there's another lip that seals against it's corresponding disk in the cap. Any gouges in that to prevent it from sealing correctly?

 

Not seeing any scratches in or on the radiator neck. When the problem showed up it overheated and blew a top radiator hose while the wife was driving it. Not sure exactly how hot it got before the hose went. Wife changed the hose on the side of the road and drove it home about 30 miles with no problem. That's when she noticed it was overheating. I figured it was a head gasket myself but a mechanic friend of mine did a test and said no exhaust in the coolant. If it was a head gasket wouldn't it heat up at idle as well? That's what has me confused, I have never seen a car that won't heat up while at idle.

 

Headgaskets can be finicky and not leak when the engine is cold etc. Sounds like you still have air in the system. There is a bleed screw near the thermostat towards the driver's side. Your wife may have damaged it by driving it home low on coolant with the new hose.

 

Also I forot to mention I had a strange overheating problem when I first got my 98 and found out the car wasn't overheatng at all but it was just a bad solder joint on the temperature gauge.

 

I had wondered if the gauge was wrong. The car doesn't really seem to get hot other than the gauge. I had Honda put the thermostat in. I thought they could get it figured out and they said the thermostat would fix it. When it didn't they said that it was the head gasket or bad crossflow in the radiator. I could tell right then they were guessing so I brought it home.

 

if it was a gauge i would think that it would act up all the time either at idle or cruise,,,,,,,,,,,chk the radiator for blockage,, and do a cylinder leak down test make sure that there is not a blows head gasket

 

In my case the gauge would only act up when the dash would get hot in the sun. Turning the AC on would get the gauge to come down so I though it was a fan problem. Out of frustration I hit the dash and the gauge instantly jumped. That was my clue so I resoldered the connections and problem fixed. The gauge is supposed to show higher temps with higher resistance, thats how the sensor works. Well if you have a cracked solder joint, which are often invisible to the naked eye, then when they heat up they expand increasing the resistance and of course the gauge would show higher temps.