How to remove air from your radiator and heating system

Weird things have been happening to my 2006 Ford Fusion during last months cold days. My heating system was working fine, as long as I was driving. As soon as the car would come to stop at a red light my fan would start blowing nothing but cold air. I ended up doing radiator flush which did not help the problem. It turned out that my cooling system had air pockets and needed to be removed.

If you have air in your cooling/heating system your engine may overheat and your heating system will not perform at its best.

To remove air from your cooling system (radiator) follow these steps.

1. Open overfill tank (warning: do not open while hot)

Overfill tank

2. Open bleed valve on the upper radiator hose. (Important: to open bleeder valve, turn counter clock wise, turn only about quarter of the turn, do not force any further. This valve does not fully open, it will only rise a bit to allow air to come out. If you force it pass it's allowed range you will damage the valve and you will need to replace entire upper radiator hose)

bleed valve

3. With bleed valve in the open position, fill overfill tank with antifreeze until you see liquid come out through bleed valve.

4. Close bleed valve (turn clockwise fully, do not use too much force)

5. With overfill tank still open, start the engine and let run until engine reaches normal operating temperature. Keep an eye on the coolant level in overfill tank, if the coolant level drops make sure you add more coolant.

6. Place your hand on the lower radiator hose, only proceed to next step once lower radiator hose feels warm. Be careful not to touch main belt (to the left), if you wear any loose sleeves, remove them so they don't get caught in the belt. Also be careful around upper radiator hose as it can get very hot and burn your arm.

7. You will notice that upper radiator hose warms up first, lower radiator hose warms up only after thermostat opens and coolant starts to flow entirely through the cooling system.

8. Once the lower radiator hose feels warm, start squeezing lower hose. Give it a few good and hard squeezes (10 should do). While squeezing the lower hose, watch the coolant level, it should be moving up and down as you're squeezing. If it is, you're doing it right.

9. Move on to the upper radiator hose (much easier to access). Do the same squeezing technique from step 8.

10. Close the overfill tank.

11. Turn heat on high. Leave it on high.

12. Idle engine at approximately 2500 rpm for approximately 10 minutes. Keep an eye on your engine temperature. If temperature gets too high add coolant to overfill tank.

13. Your're done. If needed you may have to repeat these steps.

Although these steps apply to Ford Fusion, most cars use same principle when it comes to bleeding the system.


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