Could be a leaking head gasket. Coolant can leak into the chambers when the engine is turned off (because the coolant remains under pressure), then it takes a couple of turns to expel the water/coolant from the cylinder on start up. You can test for it by letting the engine stand over night, removing all the spark plugs and turn it over, if it turns like normal from the start then I'd suspect the head gasket. If it does the same as it used to (only without firing up) then I'd rule the head gasket out and look at the starting/charging systems.