pros and cons of thermostat removal
From Felix Miata's FAQ
From Mazdaspeed FAQ
From the 1st Gen Archive - "My $150 Dollar Thermostat"
Will removing my thermostat help my rotary engine run cooler or make more power?
No and No. Mazda rotaries use a bypass style thermostat. When the thermostat is closed, the water pump recirculates the same coolant back into the block without going through the radiator. This allows the engine to come up to operating temperature more quickly. Without the thermostat, the bypass is never closed, and the engine will overheat. An overheated engine makes less power, until eventually it makes no power.
Thermostats are available in 160F, 180F, and 195F ratings for rotaries. For best HP, the 160 is the best choice. For best fuel economy, 195 is usually the best choice. Mazda usually installs a 180.
No and No. Mazda rotaries use a bypass style thermostat. When the thermostat is closed, the water pump recirculates the same coolant back into the block without going through the radiator. This allows the engine to come up to operating temperature more quickly. Without the thermostat, the bypass is never closed, and the engine will overheat. An overheated engine makes less power, until eventually it makes no power.
Thermostats are available in 160F, 180F, and 195F ratings for rotaries. For best HP, the 160 is the best choice. For best fuel economy, 195 is usually the best choice. Mazda usually installs a 180.
Why must I run a genuine Mazda thermostat?
The Mazda rotary engine has a small bypass port, about the size of a quarter, located an inch or so underneath the thermostat. You must use a genuine Mazda thermostat that has the bypass valve located under the thermostat, so that it can properly control this small bypass port. Failure to do so can lead to overheating. Most after market thermostats sold by people who are not Mazda dealers do not have the disc to cover this bypass port, so only buy thermostats from your Mazda dealer.
The Mazda rotary engine has a small bypass port, about the size of a quarter, located an inch or so underneath the thermostat. You must use a genuine Mazda thermostat that has the bypass valve located under the thermostat, so that it can properly control this small bypass port. Failure to do so can lead to overheating. Most after market thermostats sold by people who are not Mazda dealers do not have the disc to cover this bypass port, so only buy thermostats from your Mazda dealer.
Last edited by Directfreak; Aug 16, 2002 at 02:20 PM.
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NO water cooled engine should ever be run without the thermostat. If you're trying to solve an overheating problem, this is NOT a recommended fix, you should instead replace the thermostat with a new one if the concern is that it isn't opening. You could also just check it as the Haynes manual suggests.
