What causes pressure build up in radiator?
When the fluid in the cooling system heats up, it expands, causing the pressure to build up. When the radiator cools back down, a vacuum is created in the cooling system that pulls open another spring loaded valve, sucking water back in from the bottom of the overflow tank to replace the water that was expelled.
How do I lower the pressure in my cooling system?
The only way to change this pressure is to increase/decrease pump flow or add or remove restriction from the system. The water component of coolant boiling, in the hottest areas of the engine, creates expansive vapor, which further pressurizes the system.
What happens if there is air in cooling system?
When you have air in your coolant system, it causes steam pockets in the line which act almost like plugs preventing the coolant from continuing to flow. That’s why you end up with your engine overheating, because the coolant isn’t allowed to continue through or it moves very slowly.
How much pressure should a cooling system have?
Most radiator pressure caps keep the system pressure at 16 PSI so the engine coolant can get considerably hotter without the fear that it will boil off. If there is no pressure in the cooling system, the coolant will boil off.
What’s the pressure limit on the cooling system?
The cap is set to 15 psi in most cars and operates like a pressure release valve. The cap acts as a pressure and safety valve. When the cooling system’s pressure exceeds the safety limit, the cap’s safety valve opens to discharge the extra coolant. Vehicles these days have a recovery tank to store that discharged coolant.
What causes high pressure in the cooling system?
But you could also have a stuck thermostat, bad water pump, or bad head gasket that lets engine compression get into the cooling system. Fill the system and try a new cap.
What happens when the pressure on a radiator increases?
With that increased pressure the water doesn’t boil any more. It keeps transferring heat to the radiator. If that pressure is suddenly decreased (like the radiator cap being released) the heated water will spontaneously start boiling violently. This is why filler caps have a two stage twist for removal.