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Simple solution for purging the air from your cooling system

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69K views 13 replies 8 participants last post by  CSFiend  
#1 ·
After having a horrible time trying to get the air bubble out of the thermostat area, I pulled the thermostat heated it with a heat gun until it opened all the way, quickly installed it and then filled up the coolant. It worked like a champ and was the quickest I have ever gotten the air out of the system and I wanted to share this with others.
Happy Purging!!
 
#2 ·
How about a heat gun?

When the thermostat opens, coolant is pulled up from the lower hose. If there is air trapped above the thermostat it will be moved when it opens with a combination of high rpm. That's why you burp the system with the cap off, use of a funnel on the neck is helpful, and watch for the coolant to start moving with steam, then raise the engine rpm to increase the velocity of the coolant.
 
#3 ·
I don't know why heating the thermostat would help. As soon as the cold coolant hit it, it would close. Prolly with in 2-3 seconds.

I dunno why people have such a hard time with burping. I've never had a problem doing it. I usually slide a jack under the side with the radiator cap, and raise the vehicle a little.

If it's not working for you. Get one of these. http://www.amazon.com/Lisle-24610-Spill-Free-Funnel/dp/B001A4EAV0
 
#4 ·
#5 ·
I can't understand why there are so many issues regarding bleeding air out of cooling systems ie its not rocket science when refilling system it not hard to guess that that there will be air trapped in there and the only way to get it out is to run the engine up to temperature (ie thermostat opens) and run for at least 30 minutes with the radiator cap off (off top reservoir if turbo) to release air, topping up when necessary. fill over flow reservoir up to correct level then replace cap then switch off engine let cool down til cold then recheck level.

The easiest way to refill system is to disconnect / use top radiator hose as a filler/funnel to refill radiator (jug in antifreeze) then swap hose over to engine and refill engine ( I use garden hose )
 
#9 ·
I've never had any issue burping and I never do anything special. They will self bleed after a few driving cycles and exchange air for coolant in the overflow. I overfill the overflow a bit and after a driving cycle or two everything is good. Gen 1 Legacy radiator did have a plastic screw you could remove from the passanger side of the radiator which help makes sure there was no air while filling.

I also don't see the point in having the thermostat open as coolant from the upper radiator hose will fill the upper part of the engine.

I do make sure the rad cap is the highest point in the engine when filling and may jack up one end of the car to ensure this.
 
#10 ·
imho,

the 00 - 04 are much easier to fill than the 96 - 99 ej25.

in 00 they moved the top rad hose closer to the middle of the rad instead of the passenger side top corner.

the ej25D 96 - 99, tends to get a large air bubble trapped in the top of the block.
this results in less than 1.5 gal of coolant.
which tends to reduce , limit, restrict flow.
filling the system too fast traps the air in the block.
too much coolant going into the top of the block stops the air from escaping.

if there is only 1 gal. of coolant in the system,
the coolant will not flow.
 
#11 ·
use jack, raise front of car pretty darn high
Turn temperature Knob to hottest, that way the valve to heater core is fully open so the core also fills no air there.
Put in coolant.
With cap off, start car, and wait for it to drop, that is when the thermostat opens
add more coolant.
put cap on.
take for a drive.
let car cool, check coolant top off if needed.

******TOO many people fail to set temp dial to hottest, therefore they have air in the heater core. Must turn knob to hot prior to filling coolant.
Never put COLD coolant in a hot engine.