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Burping the Coolant System????

113K views 25 replies 10 participants last post by  Outback Nobhed 
#1 ·
I tried to do a search, but came up with everything except how to!! Can someone give me the correct way to burp my cooling system... I had a leaking turbo res cap and replaced it, now I have air in the system and cant get rid of it! Thanks for the help, and I'll take the flames if I missed the search thread!:fight:
 
#2 ·
You basically let the car idle for a while with the upper coolant tank radiator cap off - place a funnel in there so you don't make a mess. You basically want the system to go through a few fan cycles, it also helps if you have the heater on while you do this.

Using a "no spill" radiator funnel kit makes this a snap because you don't have to hold it. You can use just a regular funnel but I wouldn't recommend it.

I would do this when the car is cold.
 
#4 ·
You basically let the car idle for a while with the upper coolant tank radiator cap off - place a funnel in there so you don't make a mess. You basically want the system to go through a few fan cycles, it also helps if you have the heater on while you do this.

Using a "no spill" radiator funnel kit makes this a snap because you don't have to hold it. You can use just a regular funnel but I wouldn't recommend it.

I would do this when the car is cold.
What he said. Plus "burp" the system by continually squeezing the upper radiator hose by hand as the engine is warming up. You will see the water level rise in the upper coolant tank and bubbles come out. Squeeze for a couple seconds each time then release. When you see no more bubbles, chances are you got all the air out of the system. When you are done, top off your coolant level and happy motoring!
 
#5 ·
^THIS!!! Just make sure once your done top off that higher located coolant res, and make sure your res coolant tank is at the correct levels and your good to go. When you don't see anymore bubbles coming out, that means its all burpped. I know when I did my Camaro, I reved the engine so the coolant went through the engine/water pump. Just a couple quick revs help.
 
#6 ·
+1 on revving the engine. This is how I've always done it. If the engine is warm and, when you rev engine, you notice coolant starts to flow out of the cap, that is usually an indication you have most(if not all) of the air out. The main thing you're waiting for is the coolant to warm up enough to make the thermostat open, which allows flow through the entire system, thereby allowing any remaining air to find its way up to the highest point in the system (the upper cap in this case). Revving the engine acts as a stimulus to force the air bubbles out, since you are increasing/varying the water pump speed. Add more coolant to replace the bubbles that came out.
 
#8 ·
This comes in very handy when burping the system



Just put this Funnel where you fill the coolant and fill it half way with coolant of your choice

With the car running un-plug the funnel and let the burping begin..it takes about 15 min or so depending on how much air is in the system. you will see the funnel drain and fill also depending on the amount of air in the system.

Just let the car run until the bubbles stop; plug the funnel; turn the car off and remove the funnel
 
#10 ·
Reving the engine to push the air bubbles out is a bad idea. You can atomize the bubbles into the coolant, This will only appear to have bled the system. Few hours later and you are back to having a air pocket.

The idle with funnel topped up and slowly squezzing the upper hose is the best way. Yes with heater on full as to clear out the heater core. idle it passed a few heat cycles on the fans, make sure the funnel is full and then shut the car off. As the air escapes out the sides of the funnel it will displace it with fresh coolant.
 
#12 ·
+1 on setting your HVAC temperature control to full hot.

Could you explain the atomization of the air into the coolant again? I have never heard that before, and I'm a little skeptical, since reving the engine is very common practice when bleeding cooling systems.
 
#13 ·
Sure as the air gets pulled thru the cooling system the water pump hits that pocket of air. As you idle it, the air can move passed the pump with little problems. The faster the pump moves it chops at the air. breaking the air up[. The faster you rev the water pump it breaks up that air pocket into even smaller bubbles.

Just like when you put some coolant into a can, shake the can slowly, air stays, Shake the can fast and it begins to bubble up and can foam.

Most do know and after a few days the catch tank purges the system, Which is fine, but then you are driving around with a low coolant level in the catch tank and the system cant work correctly when it needs to move fluid back and forth.

This happens a lot when people bleed brakes. pump fast the peddal gets hard, few hours later it gets soft or becomes very hard to bleed. Unless you let it sit for a few hours, then bleeds up quick. When you let it sit for a while the small air moves back into bigger pockets, and bleeds right out.
 
#20 ·
You don't need a funnel although it will help. I have done mine several times without one. You will probably overflow a little and spill some coolant out here or there but just wipe it up when you are done. No big deal.
 
#23 ·
Your making this way to difficult for yourself man. This isnt rocket science...you are simply getting the air out of a fluid system. A lot of people get overly paranoid about cavitation. You have a metal impeller in your water pump...a little air is not gonna hurt anything for a short period of time, take it from a pump engineer. You will get most of it out simply by squeezing the radiator hose. Whatever is left will purge itself over time. All you need to do is take off the cap of the top reservoir, start the engine cold, and squeeze the radiator hose several times as the car is warming up. You will see the coolant level rise in the reservoir as you squeeze the hose, and bubbles will come out both when you squeeze and release the hose. When you continue to squeeze the radiator hose and dont see any more bubbles you are done. Shut the engine off, top off the level with water (or coolant), put back on the cap and call it a night. Good luck.
 
#25 ·
^^^Yea no biggie man, sorry if I came off as abrasive. I just find that a lot of people tend to dwell and make things much more complicated then they need to be. Once you spend some time and understand the mechanics of the Sti you will learn that its really not as complex as it seems. Hope you were able to burp your system alright.

-Brett
 
#26 ·
I have made this setup today on my 2007 2.5l Outback.$5 AUD funnel with thread tape to seal. Topped up the radiator then ran it for 1/2 hour watching for bubbles. After a good test run I haven’t had any overflow in the header tank. I changed the water pump a little while ago which led to the overflow issue.
61606
 
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