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Steve, Auto Service Technician
Category: Car
Satisfied Customers: 5494
Experience:  25+ yrs experience as a professional working technician; ASE L1 master technician
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why does my car smoke when i first start it up ...

Customer Question

why does my car smoke when i first start it up?
Submitted: 11 years ago.
Category: Car
Expert:  Steve replied 11 years ago.

There are a couple possibilities, depending on what is actually burning to cause the smoke. I assume you are referring to smoke from the tail pipe...

(1) If it is oil smoke you are experiencing (it will be grayish or bluish in color, and smell somewhat like burning oil) then you probably have either badly worn valve guides in the engine or blocked oil returns under the valve cover. Oil can leak down past the valves into the cylinders overnight, and then burn all at once on startup. Usually this will diminish after a minute or so of running. This is somewhat normal on a very high mileage engine with lots of wear, but abnormal on a newer car with a low mileage engine. Usually, if minor, this will run for a long time before giving you any other noticeable problems (such as fouled spark plugs).

(2) If it is bright white, sweet smelling smoke that is coolant burning in the engine. This usually indicates a failed head gasket, cracked head, or other internal nastiness that can be expensive to repair. If you are burning coolant, you want to have it repaired as soon as possible to prevent any further damage.

(3) If it is dense black smoke, that is from a lot of extra fuel burning all at once; this could indicate a leaking fuel injector or an engine control system problem. You should have the vehcicle diagnosed and repaired as soon as feasible, to prevent other damage (such as catalytic converter failure).

I hope this is helpful; if so, an accept would be most apreciated! thanks!