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Provided by the compucert T3h wag00n has been driving me up the wall for months. The temperature fluctuates wildly. It seems that no matter what I do I can't get it to run cool steadily. I've had mechanics look at it over and again and no one can figure it out. So I decided to run a little test.
First, though, you have to understand how a thermostat works and what it does. In your car the thermostat regulates the temperature of the water in the cooling system. It has a spring that contracts when the temperature reaches a certain point which then allows water to flow out of the engine into the radiator to cool. When a thermostat is faulty usually it sticks closed and causes the car to overheat. It could also fail in the open position in which case the car will take forever get up to operating temperature. If you have rubbish in the cooling system it can clog up the thermostat which will also cause the car to overheat.
So I had flushed the cooling system several times. Installed a factory Subaru thermostat, heater core and water pump. The problem kept showing up. It was suggested that I removed the thermostat.
It's an old mechanic's trick to pull the thermostat on a consistently overheating car. The water never sits in the engine long enough to get too hot. But then again, it doesn't sit long enough to get hot at all. In addition, today's cars have high flow water pumps. That means that the water will move through the system at a rapid rate. Believe it or not, that's not good if you have no thermostat. The water will never sit in the radiator long enough to cool down, so slowly the temperature will continue to rise. Eventually it could possibly STILL overheat. That was the scenario that played out in my mind. I tested the car out with no thermostat and noticed that it did reach operating temperature eventually, but significantly more than than usual.
Then I remembered a racing trick. Race cars usually don't have thermostats. But they can't go without anything, otherwise the water will get too hot. They use a "flow restrictor." It resembles a washer. It's a piece of flat metal with a hole in it and replaces the thermostat. What it does is hinder the free flow of the water in the system. It slows it down enough to allow the hot water out of the engine to cool in the radiator, but it doesn't get too hot either.
Believe it or not, I doubt they make racing flow restrictors for a 1991 Subaru Legacy with a 2.2 liter engine so I made my own. I bought a thermostat and removed the spring and plug from it. I put on the gasket and put it place. I filled the system with water and tried it out for a couple days. Running temperature was perfect. It varied but remained low, but it was high enough that the car had some lukewarm heat.
In the end, my homemade restrictor did a great job. I'm pleased. :)
First, though, you have to understand how a thermostat works and what it does. In your car the thermostat regulates the temperature of the water in the cooling system. It has a spring that contracts when the temperature reaches a certain point which then allows water to flow out of the engine into the radiator to cool. When a thermostat is faulty usually it sticks closed and causes the car to overheat. It could also fail in the open position in which case the car will take forever get up to operating temperature. If you have rubbish in the cooling system it can clog up the thermostat which will also cause the car to overheat.
So I had flushed the cooling system several times. Installed a factory Subaru thermostat, heater core and water pump. The problem kept showing up. It was suggested that I removed the thermostat.
It's an old mechanic's trick to pull the thermostat on a consistently overheating car. The water never sits in the engine long enough to get too hot. But then again, it doesn't sit long enough to get hot at all. In addition, today's cars have high flow water pumps. That means that the water will move through the system at a rapid rate. Believe it or not, that's not good if you have no thermostat. The water will never sit in the radiator long enough to cool down, so slowly the temperature will continue to rise. Eventually it could possibly STILL overheat. That was the scenario that played out in my mind. I tested the car out with no thermostat and noticed that it did reach operating temperature eventually, but significantly more than than usual.
Then I remembered a racing trick. Race cars usually don't have thermostats. But they can't go without anything, otherwise the water will get too hot. They use a "flow restrictor." It resembles a washer. It's a piece of flat metal with a hole in it and replaces the thermostat. What it does is hinder the free flow of the water in the system. It slows it down enough to allow the hot water out of the engine to cool in the radiator, but it doesn't get too hot either.
Believe it or not, I doubt they make racing flow restrictors for a 1991 Subaru Legacy with a 2.2 liter engine so I made my own. I bought a thermostat and removed the spring and plug from it. I put on the gasket and put it place. I filled the system with water and tried it out for a couple days. Running temperature was perfect. It varied but remained low, but it was high enough that the car had some lukewarm heat.
In the end, my homemade restrictor did a great job. I'm pleased. :)
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