[dvknight16]

I have a 1992 Honda Accord. The temperature gauge is showing normal operating temperature. However, it is overheating. Top hose is hotter than bottom hose. Fan running intermittently. Water pump replaced one year ago. No water leaks. What could be causing this?
I am single mom, limited income, son can do some minor repairs, Haynes Manual does not provide answer. Thanks for any help.

[TxGreaseMonkey]

The top radiator hose, on your car, should be hotter than the bottom hose. The hot coolant from the engine cools as it flows through the radiator and returns to the engine through the bottom radiator hose.

It's unclear to me that your car is overheating, when the temperature gauge is saying it's normal. Could you clarify.

Here's a link on overheating that may help you:

https://www.askmehelpdesk.com/cars-t...tml#post235973

Many Honda radiators need to be replaced around 150,000 miles, often due to corrosion and mineral buildup.

[dvknight16]

I know it is overheating because I can hear the water bubbling and feel the extreme heat coming from the engine when I raise the hood. Previously when I had overheating problems, my temperature gauge would indicate it. That's why I was so surprised when I heard all the water sounding like it was boiling, and then of course, feeling the extreme heat. The fan should have been on at that point but it was not. Radiator seems to be in good condition. What "tells" the fan to come on and what "tells" the temperature gauge the temperature?

[larry123]

How to troubleshoot 24 volt circuit

[TxGreaseMonkey]

If you can hear the coolant bubbling, you may have entrapped air. Make sure to fill the system with coolant, until it comes out of the air bleed bolt. If you have a major air pocket, the water pump won't work well. The temperature gauge is connected to an Engine Coolant Temperature (ECT) Gauge Sending Unit; the ECM is connected to an Engine Coolant Temperature (ECT) Sensor, which threads into the thermostat cover; and the cooling fan is connected to an Engine Coolant Temperature Switch.

[dvknight16]

Thank you for your help. The entrapped air sounds like a real possibility. What would cause that? I am still puzzled by the inaccuracy of the temperature gauge and failure of the fan to come on. Could those two problems be related? Is it possible that any of the sensors or sending units you mentioned need to be replaced?
Also, could there be a problem with the fuses or fan relay that would have the fan coming on intermittently?
I do appreciate your help. My son is good at doing the repairs, but he is young and inexperienced when it comes to diagnosing the cause.

[TxGreaseMonkey]

Many modern-day cars have either a degasser system to get rid of entrapped air or a bleed bolt. Honda tends to use the bleed bolt. Basically, when you change coolant, it's impossible to completely fill the system, unless the trapped air can be purged. This is the job of the bleed bolt.

Yes, the sensors could be bad, but unlikely. I would check all under-hood and under-dash fuses, just to rule out the possibility one blew. Here's how:

https://www.askmehelpdesk.com/cars-t...tml#post252145

I would also check the fan relay and the ECT Switch.

[TxGreaseMonkey]

Remember, overheating is a very serious matter on an aluminum head engine. All it takes is allowing it to overheat once; then, the head may warp, valves get damaged, the head gasket blows, antifreeze gets in the cylinders and oil, and you get stuck with a $2,400 repair bill. You don't want to drive the car, until the problem is solved.

[dvknight16]

Again, thank you so much for your help! You have given me some things to check today when I get off work. Hopefully, I will locate the problem. Thanks again.

[TxGreaseMonkey]

You son may want to replace the thermostat. It's not unusual for corrosion and mineral buildup to require them to be replaced. That would be an easy solution to your problem. Good luck.