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Coolant system overpressure protection?


vaughn610
01-04-2004, 12:25 PM
When the system is in a closed loop (thermostat shut), what essentially protects the engine from an overpressure condition as the coolant heats up and cannot flow to the radiator? Normally the relief valve goes to the overflow tank, but how does this work if the engine loop is closed? Is there an additional relief valve, or is there still a flow path to the radiator even with it in a closed loop?

RABarrett
01-05-2004, 08:50 AM
I am not sure to what you refer when you mention closed loop. In the cooling system, the thermostat opens at the set temperature to allow coolant into the radiator. Until it opens, coolant is not allowed into the radiator to allow for quick warm-up. With reference to the cooling system pressures, the radiator cap controls the pressure, controlling boiling points for the coolant. When excessive pressure occurs, the cap relieves the pressure into the overflow bottle. By the way, closed loop refers to one thing controlling another, such as the O2 sensor telling the computer about mixture chemistry, allowing the computer to compensate... Ray

Crang
01-08-2004, 10:21 AM
The thermostat is for a northern climate vehicle. If you car didn't have one, it would take a bit longer to warm up. The problem would mostly be on the highway because you would have no heat, since all the fluid is constantly being cooled. In places like California or Nevada most cars don't have one. Some cars there don't even have windshield wipers!

If your thermostat closes, the engine will eventually overheat. You can prolong your drive by turning on the heater full blast. This works because the water from the engine always passes through the heater core with or without a thermostat.

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