Air trapped in the coolant system can be caused by several reasons, such as improper coolant refilling, a radiator flush, leaking radiator hoses, a leaking heater core, a poor-fitting radiator cap, and even a blown head gasket, to name a few.
For the purpose of this article, I will discuss improper coolant refill even though it's a misnomer of sorts. After all, you just pour some coolant or distilled water in the radiator and that's it, right?
Well, yes. In theory, anyway.
The issue is not necessarily how you choose to refill your coolant to the optimal level, but rather what you do during the procedure, and that involves burping the system.
Some vehicles actually come from the factory with cooling system bleeder valves, which make removing air pockets much easier.
C3 Corvettes do not have bleeder valves.
In the case of my 1976 Corvette, I simplified the cooling system by deleting the heater hoses when I rebuilt the air-conditioning blower and installed a new heater core. At that point, I chose to plug the inlet and outlet heater core tubes and get rid of the old hoses which helped clean up the engine bay.
The rest of the system remained unchanged.
BURPING THE COOLING SYSTEM
A while ago, I heard about funnels specifically designed for burping cooling systems, but only recently gave them a serious look when I had to replace the thermostat.
For under $20 it's hard not to spend the money for something that not only works better but can also be used on any vehicle with a liquid-cooled system. So I ordered one.
The funnel also has a stopper that keeps the excess coolant in the funnel when it is time to remove it. You can then quickly and safely return unused coolant to the container.
TO DRILL OR NOT TO DRILL
I am not sure if this "tip" qualifies as an "old wives tale" or an "urban legend," but I have to admit that I've drilled small holes in thermostats in the past.
Not sure if it really works on not but I am starting to think that you only need to bleed or burp the cooling system if there's air in it, something that could be avoided by filling it properly in the first place.
Otherwise, I am sure GM engineers would've added a bleeder valve at the time if this was a problem because of a design flaw.
On the other hand, if air is somehow entering a pressurized cooling system there has to be a good reason for that to be happening and you should investigate that first.
Anyway, I will not be drilling holes in my new thermostat this time. Instead, I will fill and burp my Corvette's cooling system with the help of my new Spillproof Funnel.
I've been using green antifreeze/coolant (#sponsored) in my vehicles for a long time. Don't ask me why because I do not have a specific good answer.
I've seen coolants in red, green, and yellow, and I am guessing that their formulations are different for good reason and, therefore, not a good idea to mix them.
In a pinch, all I do is add distilled water.
Again, I've used the green stuff for years and, as far as I know, it's the right choice for my 1976 Corvette Stingray. You can certainly research the subject and come up with your own conclusions.
HOW I DO IT
Again, by personal choice, my car does not have the heater core and associated hoses installed, so the burping procedure I do for my car will differ if yours does have a working heater, which is part of the cooling system.
In that case, all you need to do is turn the heater on while you burp the system.
I started by installing the Spillproof funnel, as shown above, I removed the stopper, and I added coolant to the funnel about half-way. I then started my Vette and allowed it to idle until it reached operating temperature while making sure there was enough coolant in the funnel. You don't want air entering the system by allowing it to run dry.
Once the car reaches operating temperature, I shut it off and use the funnel stopper to keep the extra coolant in the funnel which then I pour back into the bottle.
Any engine coolant that ends up on the ground must be neutralized immediately by pouring baking soda, sand, kitty litter, or a garage absorbent product (#sponsored).
Once the coolant has been completely absorbed and you've cleaned the area, you can carefully put it in a plastic bag and dispose of it properly.
SAFETY
Engine coolants are dangerous to pets, humans, and the environment. Please inform yourself on how to handle them and help prevent a tragedy from happening.
It's a good idea to use nitrile gloves (#sponsored) while handling any kind of engine antifreeze/coolant.
WATCH THE VIDEO
Whenever possible, I try to include a video that shows some of the steps involved for a particular procedure, and the one below covers the process of burping my 1976 Corvette Stingray's cooling system, something that may be advisable if your car is showing signs of overheating.
But keep in mind that working close to a running engine is extremely dangerous, so if you're not comfortable, let a professional mechanic handle it.
