moniks

does anybody have any idea of the life span of a 190e thermostat?

MTI

Although there's no "expiration date" the thermostat should last a 4-5 years. I've found that many thermostat failures arise from leaks in the plastic external housings that some part suppliers were using rather than the metal housing. Also, there seems to be some correlation between not using the MB or MB type coolant. Using those green coolants that typically go on sale for $1 a gallon have the wrong pH balance for the aluminum engine and cooling system parts, resulting in excess salts in the fluid, which accumulates on the thermostat and cooling journals. Considering that the MB coolant isn't particulary expensive and regular system maintenance only calls for changes every 2 years, it's false economy to use anything else.