Loss of coolant and white exhaust smoke are two indicators of a leaking cylinder head gasket. Your mechanic can do a chemical test at the radiator or coolant reservoir to verify that. You can also add a small bottle of dark purple dye to the coolant, then search a few days later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If you see the dye inside the tail pipe, a cylinder head gasket is leaking.
GM also has a big problem with non-flow-matched injectors. With higher mileage one or two will run a little lean leading to intermittent misfires. To find that, switch the injector from cylinder # 1 with one of the other ones, erase the fault codes, then see if the misfire code sets for that other cylinder.
Monday, September 30th, 2013 AT 8:46 PM