Rep Power: 0

I have a 1997 civic ex, Recently I noticed that the fan comes on pretty late, when the needle is 3/4th of the way up, or it will come on at 1/2, then shut off, temp gauge goes up, then kicks back on around 4/5 of the way up.
About 2 weeks ago the temps wouldn't even pass halfway up. the fans would turn on and i could keep the car idle for hours without issue.

I notice now that if i sit idle and the fan comes up, it shows the temps still rising. The only time the temp gauge is half way is when the car is moving, so I know coolant is flowing through the system.

One weird thing did happen today. I turned on the heater to help bring down the temp gauge, but instead of hot air. It blew out cold air. I had it set to just blow in air from outside. And climate control was set to hot.

Also I know coolant doesn't get cold right away, but if I turn off the car, and the. Put the key to ON. It shows that the temps have dropped to about 1/4 on the guage

I'm thinking it's the ETC.

I was thinking the wiring that goes to the fan switch has gone bad, but the fan does turn on

Besides that maybe there's air in the system. I did hear a gurgling noise from the heater core area a few days ago when I turned the car off. Any ideas?

Even doing 5mph puts enough air through the radiator to cool it down.

At home idling for 5 minutes. where the temps sit. my obd sensor claims the temps are at 246F.

 
Rep Power: 209

Sounds like a breached head gasket. Have you been checking coolant level in both the radiator and reservoir often since the temp gauge rising issue started? Low level of water or air bubbles in the cylinder head can cause sporadic dash temp gauge readings because those two situations effect how thee ECT monitors temp. You may want to check head gasket with a block tester. If block test blue liquid turns yellow or green then there is exhaust emissions getting into the coolant via a head gasket breach. If block test blue fluid doesn't change color then a leakdown is still needed to rule out a headgaskst breach. Generally, a blown head gasket symptom in these (Honda) engines is low coolant level in radiotor combined with excessive coolant level in reservoir.

If it were mine I'd first check for external coolant leaks by viewing from underneath the engine while the engine runs from cold to operating temp. If no external leaks are seen then secondly I would replace the radiator cap with a Honda genuine cap and clean out both the reservoir and the tubing leading from the radiator neck to the reservoir and monitor both the radiator and reservoir coolant levels daily for a week for changeschanges. If the issue persist I would rent (free) a block tester from an autoparts store , $10 test fluid, and do a block test on it as mentioned above.

Other possible causes are:
Coolant thermostat stuck partially closed during operating temp.
Waterpump is weak/failing
Radiator blockage either internally or externally (object covering core).
Leaking heater core inside cabin (floorboard wet?)
Other that I may have left out