My Civic has been overheating for a few weeks but yesterday took the freaking cake & ice cream.
It overheats when I'm going up a hill for even a few seconds & when I have the AC on if I'm going down an evenly leveled road. When it overheats the coolant goes right back into the reservoir boiling.

There are no leaks. I checked to see if it was a head gasket issues by taking the radiator cap off, turning on the engine & watching for bubbles for a few minutes...No bubbles.

There's no smoke out of the tailpipe.

There's no coolant in the oil(dipstick).


I started off small by replacing the Thermostat, Radiator cap & flushing the Coolant & bleeding the system(in the engine & radiator)....still overheats.(still no leaks BTW)

I'm about to just buy a new radiator just to single it out, but I don't know if that is the issue. Could it be something else? What else do I check?

 

Every time before starting out when the engine is cold, remove radiator cap and check that the radiator is completely full. If it's not staying full for whatever reason, there will be overheating.

Of course, don't keep driving when overheated.

On my former car, a 95 DX, some the thin brass fins on the radiator were corroded and falling off. It looked like most of them were intact, but it still reduced the cooling efficiency to the point that there was overheating when going up hills.

Also the inside of the radiator can get clogged up, particularly if "stop leak" has ever been used. So a new radiator could be a safe bet.

 

Yeah I have used that stop leak stuff alittle over a year ago when I didnt know too much about cars. I'll check out rockauto see what radiators they got.

 

So I got my New radiator today from Rockauto. Installed it, put coolant in, bleeded, and went for a ride.
Still overheats with the AC on and during uphills(since I live on a hill).
My radiator fan turns on at operating temp(can be heard at every stop light & sign).

The Thermostat opens as well because while bleeding the system I have the cap off, and the level of coolant goes down slightly but slowly in the radiator when the fan comes on.

Still no leaks btw.

Is replacing the Headgasket the only solution?

I wanna try every option before opening up the head, since it would be such a big task for me.

Thank you in Advance!

 

Is water pump pumping water?

I have seen a car with no vanes left on the pump due to cheap owner keep on using straight water for a long time. Vanes were corroded off, water was rusty red.

There was another case that some one dropped a small socket in the cooling system. That socket was found within the pump's cavity, only after the vanes were bent. Not enough to cause overheat but flow rate must have been compromised.

 

I replaced the Water pump Spring of last year(aftermarket). But anyhow..how would I check to see if it's pumping alright?
Far as I know I haven't dropped anything in the coolant system :P

 

When you did radiator-cap-open check for bubbles, did you see water flow?

It could be the thermostat you replaced is faulty. Cook it in a pot of water to see if it opens at the right temp for right amount of opening.

It could be faulty hoses that are coming apart inside, acting as a check valve, due to a section of it is hanging inside. There was a case like that on an airplane's oil cooler hoses. It is hard to think the same for radiator hose because it is much larger in diameter.