Burping Radiator Tip

When using this or similar radiator funnel kit to burp my radiator when you turn the engine off, huge bubbles come up into the funnel.

$21 OEMTOOLS No-Spill Coolant Funnel Kit, 15 Piece Fluid and Oil Funnel Set, Allows Access To Hard-To-Reach Radiators

OEMTOOLS 87009 No-Spill Coolant Funnel Kit, Near Universal Fitment, Translucent, 15 Piece Set, Cooling System Funnel Allows Access To Hard-To-Reach Radiators
I recently “burped” at least 14 sets of huge bubbles from my radiator simply by switching the engine off and watching the funnel neck. This was 14 more sets of similar bubbles than I have ever burped from my radiator in the many occasions I have attempted to clear the air bubbles from my Taco’s cooling system.
I discovered this technique when in a hurry to finish burping my radiator. I cut off my engine, and watched the neck of the funnel from the driver’s seat. The coolant in the funnel appears to begin flowing/sucking downwards, into the radiator when all of a sudden a big

 

... a big group of bubbles came bubbling to the surface. This shocked me!
I had never seen bubbles bigger than carbonation-sized in any of my prior attempts at burping the radiator. Consequently, I continued to run the engine for maybe a minute or two before cutting it off again and waiting for the the coolant to begin sucking into the radiator with the big group of bubbles that invariably came out in the opposite direction. I was even getting more big bubbles upon restarting.
I continued this process of starting and stopping the engine with the heater on and vent running full-blast for at least 14 cycles. I went to 14 cycles because I continued to get huge amounts of bubbles from my radiator with each attempt.
Finally, as the size and number of bubbles started to decrease I began incorporating a reverse and start into each cycling of the engine. This was my attempt as "shaking" the remaining bubbles from the coolant system. Sure enough, kind of like burping a baby, this rocking back and forth caused significant amounts of bubbles to exit the radiator into the neck of the attached funnel.
I am chastened to say, that based on the volume of gas removed from my system via this method, I have failed miserably at all heretofore attempts at bleeding the system.

 

You can use a 2 liter soda bottle cut in half and turned upside down. Much cheaper, same concept.

 

Good. Is starting and stopping the engine while burping the radiator commonplace on the forum or did I discover something?

 

You're supposed to let the engine run with the heater on full blast until the thermostat opens. The coolant will cycle through the heater core when heat is on full blast and help purge the entire cooling system of air.

About 10-15 minutes of engine run time give or take for the thermostat to open. Then add more coolant as the thermostat continues to open and close a time or two more. The thermostat should open and suck the coolant down the radiator about 3-5 times total maybe a little more.

You want to try and time it right as you poor more coolant in the radiator otherwise additional air can be sucked into the system and it will take a little longer to burp completely.

Then let the engine cool and after it cools completely (usually the next morning) I'll double check the radiator coolant level. Never open a radiator cap when hot or warm as it's a pressurized system and will scald you with boiling coolant if you do.

In other words, no you don't turn the engine on and off multiple times. The burping process will just take longer if you do, which you've discovered.

 

Maybe I did discover something? Because burping the rad in the manner described ^^^ I never got more than carbonated drink-sized bubbles to leave the radiator. However, by starting and stopping the engine multiple times after the thermostat opened at 190 degrees I was able to purge what might have been a 1 liter bottles worth of air from the system. - Stated differently, I never got even one large bubble by following the directions cited in this forum, or by running it continuously.
Thanks, I have not checked the level since doing this. I will check it again in the morning once it's cooled.