Coolant vacuum systems are fairly simple, we have covered nearly every aspect of them in various articles here over the years, whether it is diagnostics, servicing, or even just general knowledge of how they function. When you learn about something new, you feel the need to share it, and that is what brings us here now.
Coolant Vacuum Systems Process
While air pockets have always been an issue with engine cooling systems, modern vehicles are much worse. The entire cooling system is sealed in a modern vehicle; the only access point is the overflow tank, which is now considered a reservoir instead of just an overflow. There isn’t a way to purge air from the system without burping the coolant hoses. This means lots of spilled antifreeze, and potentially burned skin because the engine has to be running to do it.
Trapped air in the coolant vacuum systems leads to all kinds of problems, from overheating to erratic temperature readings, ECM fault codes, and poor drivability. When a sealed cooling system gets trapped air, these pockets can get stuck in over sensors and other areas, wreaking havoc on the system. Getting these out of a sealed system requires lots of effort or driving and waiting. Nobody has time for all that.
This is best done with an empty system, but you can use it on a full system too. You need a decent size air compressor that can supply a constant 90 psi, preferably with a drier system. The heater should be turned on (engine off). The tool is inserted into the neck of the radiator service port or reservoir tank using the best fitting adapter. It should be snug in the opening. Turn the knurled knob to seal the adapter in the hole. Connect the vacuum module to the unit, with the ball valve open. Then connect the airline to the vacuum unit. This should start the process, you will hear a loud hiss, this is the air blowing over the valve, which draws a vacuum.
How the coolant works inside the vehicle?
The gauge should start climbing. Once it reaches 24-26 inches of vacuum, close the ball valve. Your radiator hose may collapse, that is normal. If you can’t reach this level of vacuum, you may have a leak or an overflow hose needs to be clamped off. Wait 20-30 seconds and check the gauge again. If it is stable, your system is not leaking and you can continue.
If you have a lot of vehicles, this radiator vacuum tool will save you a lot of time, especially as winter is coming, so project vehicles that might not have enough antifreeze in the system to keep it from freezing can be saved in just a few minutes without starting the engine, bringing it up to temp, etc. It is also really helpful in finding leaks in the coolant vacuum systems.