2004 Accord LX 4-cylinder, 296K
Engine is overheating, The lower radiator hose is cool after running the car, upper hose is hot.

• changed thermostat, but no change
  • tested the original in boiling water and it opened up immediately.
• New radiator cap
• Flushed the system, and did an oil change. No signs of oil in the coolant, and no signs of coolant in the oil.
• Bled the system for a while with a funnel kit, pumped it up to 3k-4k rpm to get all the air out.
• Took off the passenger tire to see the water pump. no leaks and no metallic sounds.
• The lower hose is cool and i can feel it has coolant in there. but its not hot enough to open the thermostat.
• The front of radiator is beat up from normal wear and tear. not sure if this could cause it, maybe blockage?
• No leakage near the heater core valve.
• No codes in the system

Could the water pump be broken and not make any noise? maybe bearings are shot?
Any ideas are appreciated. I have 296K on the accord, trying to get this baby in the 300 club!

 

On most other manufacturers vehicles, the cooling system has hot coolant going to the top hose of the radiator
It then flows down and cools and returns to the engine from the bottom radiator hose.
This means top hose is hot and lower is cooler.
Well, Honda has the coolant flow into the radiator thru the bottom hose
And back to the engine thru the top hose.

If the top hose is hot and the bottom hose is cold then coolant is not flowing thru the radiator.
Sometimes this is caused by a stuck closed thermostat. You replaced it and you know the old one works.
So probably not the thermostat.
The only other things it could be is the water pump is not moving the coolant
Or there is a blockage.
Have you tried turning on the heat in the cabin??
Are you getting heat??
Water pump or blockage??
If you haven't flushed the cooling system then may well need it????
Good luck