Engine Temperature Guges goes high when going uphill

[quote:9f932167b9="HondaUser"]Hoda Civic 93 140,000 miles

Hi,

I relpaced the new radiators, hoses, and themostats on my civic about a year ago for coolant leakage and it has been gonig fine.

But recently, when my car going uphills, the engine temperature guage would go up to around 3/4 and go back to normal gruaduall ( which is about a quarter high) when it goes back to normal ground.

I could not find any leakage on coolant, and when the radiator cap is open, the coolant was not boiling, and the fan is running.

What the problem might be? (the weather is a bit hot recently like 105 F).

Thank you very much[/quote:9f932167b9]

Try bleeding the air out of the system

Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.

Doesn't work test the thermostat or replace it.