My '94 M42 318i appears to be blowing water (coolant) out the exhaust. I don't see any blackening of the remaining water or see any water in the engine oil? Could it still be a head gasket? What else could it be? Is there another way that it could be getting to the exhaust? I'll pull the plugs tomorrow and see if there's a difference between them? Are head gaskets or anything else that could cause this a common problem for these engines?