How to Burp Your Car's Cooling System

"Burping" the cooling system allows trapped pockets of air to escape: Air pockets can cause overheating because there will not be enough coolant in the cooling system, even if the radiator and coolant reservoir look full.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Engine Coolants

1. Add a mixture of one-half water and one-half antifreeze to the radiator. Fill it right up to the top.

2. Fill the overflow/coolant reservoir with the same 50/50 mixture.

3. Leave the radiator cap off, turn the engine on and let it run until the radiator "burps": You will see the coolant level drop and may see or hear a large air bubble come to the top as the system burps.

4. Keep an eye on the temperature gauge throughout this process.

5. Refill the radiator to the top and coolant reservoir as needed.

6. Put the radiator cap back on.

7. Note that if the engine runs hot after this procedure there may have been another pocket of air that "burped." Let the engine cool down and then add more coolant to both the radiator and the coolant reservoir.

Tips & Warnings

• Your cooling system will need to be burped after coolant has been drained from the radiator or any other part of the cooling system.
• Always dispose of coolant properly - do not pour it down the drain or sewer. Many service stations, repair shops and parts stores will take coolant so that it can be recycled, or you can bring it to a recycling center yourself.
• Never open the radiator cap when the engine is hot! The radiator is under pressure, and it could spurt out and burn you.
• German and Swedish cars have plastic coolant reservoir tanks that are also pressurized - you must wait for the engine to cool down before opening the cap.
• Never let the temperature gauge go into the red - turn the engine off before the car overheats!

Who Can Help Sponsored

• Ask a Mechanic Online Now

[tony1675]

on 6/17/2009 My 1999 Jeep cherokee overheats after driving for about 25 minutes - fluid goes right into the reserve tank. Thermostat has been change and problem still exist - any recommendations

[audistud2002]

on 11/2/2008 I changed the thermostat burped the radiator on my 71 Catalina but coolant still flows out overflow drain hose when car is parked after being driven ( It drains about one cupful of antifreeze)The car does not run hot. Any thoughts

[bigstar3]

on 8/4/2008 If the auto "burps" twice and still over-heats, this may be due to the overflow pressure valve nozzle on the top of your radiator running to the overflow container.

A way to "unlog" this pressure valve is to put a little kerosene in with your coolant. Pull off the top hose of the radiator at the point where it enters the water pump/engine block. Hold the hose upright, and start your engine. Continue to feed the kerosene mixture into this hose until you see fluid flow into your overflow tank. Once you have done so, place a condom (yes, a condom!) over the hose, and poke a hole in the tip. Place the hose back on the block.

The condom filters and residue, and dissolves back into the coolant. The lubricant from the condom also aides in removing any corrosion that water from the coolant creates in your radiator.

I hope this helps.

[jamminehow]

on 1/26/2008 I have this problem. 98 olds van overheated after NTB replaced the thermostat. On a cold start I drove down the highway about 5 miles when it overheated. NTB ran the engine at 2000 rpm for about an hour with no problem. The next day exact same problem. When it sat for a while to cool, I drove it again and heard air bubbling quite loud and it was fine. Hopefully it all came out?

[supernelson]

on 7/29/2007 Thank you all for your comments. Bleeding trapped air in the head of my 95 accord seemed to have solved my overheating problem. Thanks CJC.