Lotus Elan and Lotus Elan Plus 2 Forums

Back in the day, a brass discs with various sized holes were used in place of a thermostat, especially in cars that raced. These discs were commonly called blanking sleeves. It was believed that thermostats often failed and during a competition could cause engine failure. This in spite of the fact that millions of cars on the road had thermostats that never failed during their lifetime. The size of the hole was gauged to meet enough water flow through the radiator to keep the car from over heating on warm days. The downside was on cold days, some covering of the radiator was necessary to get the engine up to operating temperature. Oft times this meant covering a portion of the radiator for an early morning session and removing the covering for an afternoon race. I never understood this, as I wanted the engine to operate at its best peak power temperature along with its oil any time the car was on the track, and a thermostat was the best way to conrtol the engines temperature.

chickenstock10k wrote:Why even put the the remains of the thermostat back in at all?

Possibly could not get it out with inadequate tools on a wet & windy night.