Flushing Antifreeze

[2003TRD]

I did my antifreeze drain and flush last year (using distilled water of course) but I just ran across the mityvac website where it says that you should use a vaccuum system when you drain and fill your antifreeze because you get air bubble trapped in the system and it makes hot spots. When I did mine, I figured the water pump should pretty much circulate the air and fluid through the system anyway and I can just top off after a few days. Is there any potential harm in doing it the way I did versus using a vaccuum bleeder (that they sell)

 

[ARB1977]

I just did mine on my 2002 Tacoma. I perfer the machine method becuase i think it gets more of the crap out vs just draining it out plus its faster.

 

[2003TRD]

Yeah, I didnt use a machine. Not going to buy one and I dont trust dealers/garages to use distilled water only. So I flushed with about 10 gallons of distilled before I filled it back up 50:50. Anyone think that air bubbles can become somewhat permanently trapped creating a HOT spot? I figured it would all get circulated through from the water pump.

 

[MC5W20]

I don't think air can get permanently trapped. It will be a continual process of purging the air. One method to purge the system of air is to: underfill the cooling system by approx. 4 inches below the radiator neck. Run the engine until thermostat opens then fill up the remaining portion of the radiator. You will get spill over using this method. Install radiator cap. Keep an eye on the overflow tank level for next couple of weeks. This method will allow the minimal amount of air left in the sytem if any.

 

[Ray H]

Generally, pressurized cooling systems are self-bleeding. (Why "suck" it out, when the cooling system pressure will happily "blow" it out?) Systems with coooling passages above the level of the top of the radiator may require help, though. Such systems usually include an air purge (or "burp") screw to relieve trapped air. My '96 Accord I4 had such a screw threaded into the thermostat housing. After a coolant changeout, with the motor idling and the system warmed enough to open the thermostat, all I had to do was loosen that plug briefly until bubbles ceased oozing past the loosened plug. In systems without an air purge screw, just checking the coolant level in the radiator over the next several days after a coolant changeout and topping up as necessary is all that's required. (Be sure to move the heat control valve to its hottest position to purge trapped air out of the heater core.) Unless your vehicle owner's manual states otherwise, you don't need something like a Mityvac to purge the air from your cooling system.