I'm getting weird symptoms from my 560sl with 53k miles. White smoke from exhaust but now I don't have it. My oil is still normal. I was working on my coolant system and removed the thermostat housing and found no thermostat so I just order one waiting for it to come. The thermostat housing is closed without a gasket so water is leaking out but I'm not driving the car. The reservoir has no bubbles when running. Any other way to find out if the head gasket is actually blown ?