I have a 1996 Honda Accord with a 4 cylinder engine and an automatic transmission.

It was behaving just beautifully until I took it in for a check up before a long road trip. My mechanic replaced a coolant hose and forgot to put the radiator cap back on. The radiator boiled over and the engine overheated. It's been misbehaving ever since.

The water pump was leaking, the engine was overheating, and the engine would shut off randomly while stopped at lights or pulling into parking spaces. So I got the water pump and timing belts replaced for the overheating and the distributor replaced to deal with the engine shutting off.

Now it idles rough, shifts at a higher RPM, still overheats (for longer trips it starts to overheat while idling at stop lights, but drops back down when it gets up to speed), and occasionally the key comes out of the ignition really hot, which never happened before. My mechanic has pressure tested the cooling system and can't find a leak, even though it seems to keep taking more coolant. He says he doesn't think its the thermostat because he let it sit and idle for ~40 min and it didn't overheat.

The engine has new spark plugs and spark plug wires, and the EGR valve has been replaced in the past few years.

Any thoughts or suggestions as to what is causing the overheating would be greatly appreciated. I also am not sure if the rough idle and shifting issues are just due to the new distributor or what... any ideas there would be great too. Thanks in advance!

 

overheated it till head cracked or head gasket failed

 

The same exact thing happened to my 96 accord. A coolant hose to the engine busted and I overheated. Luckily the only major thing damaged was my spark plugs. After getting those replaced it has ran beautifully. My key does get hot as well at times. Have you checked to make sure that the fans are working? I would also have your seals checked if possible. My valve cover became so hot that the gasket literally hardened and became glued on so tight to the cover; it then started leaking. Now my transmission seal is leaking. I'm not quite sure if this is due to overheating or just being an older vehicle. My timing belt cover now makes an odd ticking sound when the engine is running because the plastic became so hot. Has your mechanic checked for a cracked engine block or head gasket? After overheating my car would run for a second and then shut off and it would not start again. A cracked engine block or head gasket was the mechanic's first thought about what was wrong with it.

 

The oil isn't foamy and it doesn't blow white smoke or eat oil as far as I can tell, which should imply the head gasket isn't cracked. Is it possible to have none of those things happen and it be cracked? My mechanic changed the oil after the engine seriously overheated the first time, and didn't say anything about coolant in the oil, and since it's never gotten up into the red since, I don't think it could have cracked if it wasn't cracked already. Would the pressure test of the cooling system show if the block was cracked?

I'll look into the fans and the thermostat. I know it looks like the valve cover has leaked oil, so it's a good idea to change that, but would that cause overheating?

 

I highly doubt it is a cracked engine block or head gasket. Does your car run fine until it gets hot and then stalls? Could be timing issue, computer module, O2 sensor or maybe even cadallitic converter. Sounds like you have more than one issue. The leaking valve cover gasket would not cause this unless it is pouring out oil which does not sound like it is. It is something that needs to be changed but is not causing you to overheat.

 

Might also be a clog in your radiator. Thermostat might be stuck causing it to not circulate the water when its idling and only dropping back down when its running.

 

I got the car back from my mechanic, he never got it to overheat, even though he idled it for extended periods and drove it around. I drove it the 6 miles home and it didn't overheat. He couldn't find anything wrong with it, says that the thermostat and the fans are working fine. He did suggest that maybe the head gasket could be blown, but he doesn't think so. Evidently it can crack and not have oil/coolant mix, it just depends on where it cracks (ie if it is cracked it would be leaking into one of the cylinders).

It isn't stalling anymore. I do know that the catalytic converter is on it's way out (has been for years, but the gas mileage has been fine, so I've been waiting). Maybe it's finally time to change it, you're suggesting that might be the cause of the rough idle? Since the timing belts *just* got replaced I'm going to rule out a timing issue, but I did have the computer replaced with a used module, so I'll reserve that as a possibility of last resort. Also, the O2 sensor has been replaced in the past few years, but is that something that could be damaged by overheating?

If it starts overheating again I think I'll try and replace the thermostat myself in case it is sticking intermittently (though I've been told if it sticks it will stick all the time). Beyond that I'll try testing and tracking down some of these issues.