I drive Toyota Highlander 2005. It's a gasoline car. I filled up the tank a few days before this happened (right before Halloween.) It then sat in my garage for about 3 days. (I live in the WA sate and the temp at night was close to freezing.) I then needed to drive it yesterday and when I started it up, a black plume of smoke came out from the exhaust. After that happened, the engine has been running fine.
How would you explain it?
Start up black smoke sounds like a subtle oil leak into one of the cylinders or onto the valves. My guess is worn valve seals. Its also possible to have a leak at the head gasket (or crack in the head somewhere) that allows low pressure return oil to slowly drip into the one of the cylinders or onto the valves. If it were a leak on the high pressure side of things you'd see a constant stream of black smoke. The fact that it only occurs at startup tells me it accumulates after a delayed shut down.
How many miles on the engine? Has this vehicle had regular oil changes throughout its life? Has it ever been driven in an overheated condition for an extended period of time? What do you think is the life expectancy of this engine (in miles)? My guess is 200,000 miles or so, depending on how regularly the oil was changed...
