I have a 99 honda civic EX auto, coolant keeps disappearing in the res. tank and I keep getting air in the cooling system. I have replaced the radiator hose, therostat and flushed coolant. I believe there isnt any coolant leaks outside/ no smell of coolant. Car does not overheat and runs fine. No smoke coming out of exhaust when running hot or cold.Car does have a radiator that looks like it came out of a different car cause factory or auto zone radiator cap wont fit it.
Air does not cause coolant to disappear from the cooling system. Anytime a hose or thermostat is replaced, The radiator should be filled to the top and the plastic coolant reservoir should be fulled 3/4 full. Start the car and drive it till the dash temperature reaches the temperature stamped in the thermostat. Park the car in your driveway and refill the radiator to the top and coolant reservoir 3/4 full when the engine is stone cold. If the radiator still is loosing coolant have a trusted private mechanic do an inexpensive *cooling system pressure test to find any external or internal coolant leaks. Check the weep-hole on the bottom of the water-pump in-put shaft casting.
Sounds like you have a bad radiator cap, when it gets hot the excess water flows into the overfill tank and when it cools off it does not pull the coolant back in. Thats the job of the cap so I suggest you take it to Auto zone and have them pressure test the cap and the cooling system, when you do you will see the leak if it's in the radiator or heater core core system or if it's just the cap. Hope this helps and good luck.If your cap tests OK then you have a pin hole leak on one of the hoses or the weep hole on the water pump is leaking.
hi Set the heater totally onto warm (would not might desire to be blowing, in simple terms set to warm). this could determine that the heating equipment is roofed into the equation. eliminate the coolant filler cap and precise up the coolant to the utmost mark. start off the engine and enable it warmth up till the cooling fan has been on and rancid a minimum of as quickly as. change off the engine and replace the coolant filler cap. If the coolant explodes from the enlargement tank in the previous it has even warmed up then the pinnacle gasket has very rather probable long previous. If the subject is in any different case no longer solved then have a cylinder compression or cooling equipment sniff try complete. Regards Geordie
