I have coolant leaking from the thermostat housing on my '92 190E 2.3l. My thermostat is also not working. I add a gallon or so of coolant and i can drive maybe 40 miles until the coolant light comes back on. The leak seems to get worse as the engine warms up and the pressure increases in the coolant lines. Would it be okay to run the car without adding coolant. It seems like there is coolant in the system even when the lights on and I know old vw's are air cooled so it sounds some what logical that it would be okay or am I way off? Also how hard is it to replace the thermostat housing and thermostat? Thank you...

 

You absolutely CANNOT run the car without coolant. You will do serious damage to the engine (cracked head or block). Air cooled VWs were made to be air cooled with special fans, ducting and cooling fins. Nowhere do you have this equipment on your Benz.

You need to determine if the leak is from a crack in the thermostat housing itself, a bad hose, or the thermostat gasket. The thermostat is relatively easy to replace and should take you only half an hour to do so. Get the original Benz one. The aftermarket ones are chintzy and usually don't come with a new seal.

If the housing is cracked, replace it. Don't try to repair a crack.

If you can't handle the repair, take it to a mechanic to make sure it's done right.