BLUE EXHAUST SMOKE
Vehicles subject to a smog check require a visual inspection for excessive smoke (either blue, white, or black) being emitted from the exhaust/tailpipe, and as well as (which most car owner's don't assume), any smoke coming out of the engine compartment. A vehicle which produces or emits excessive blue smoke, black smoke or white smoke can not pass a smog check in the State of California, and will fail the inspection. A vehicle which emits visible smoke will need to have the fault diagnosed and repaired before being able to pass the emissions inspection. Vehicles with engine malfunctions may also emit smoke from the engine compartment. This too will cause a visible smoke test failure. Note: If your vehicle has smoke emitting from the engine compartment, we highly recommend stopping vehicle operation until the cause of the smoke has been investigated and repaired. Checking the engine oil level at regular intervals will indicate if there is excessive oil consumption.
What Causes Excessive Blue Exhaust Smoke to Emit from the Tailpipe?
Visible blue exhaust smoke from the tailpipe may indicate one of two things:
- The engine is not burning fuel properly, leaving behind high amounts of Carbon Monoxide (CO), resulting in excessive blue smoke being emitted from the tailpipe. These vehicles will experience increased fuel consumption as well.
- Engine oil is seeping into the combustion chambers. Oil is mixing with the fuel & air mixture, leaving behind high amounts of carbon, seen as excessive blue smoke being emitted from the tailpipe. Oil seepage may occur due to defective piston rings, valve seals, or Positive Crank Ventilation (PCV) Systems.
- Dirty or non-functioning PCV valve resulting in engine oil blow-by.
Blue exhaust smoke from the tailpipe only at start-up may be an indication that your vehicle's engine has worn piston rings or damaged or worn valve guides. Should this be the case, your vehicle's engine may also be emitting an engine rattle noise. Oil leaking into the engine cylinders may also cause a misfire, rough idle, and fouled spark plugs.
What Causes Excessive Blue Exhaust Smoke to Emit from the Engine Compartment?
Blue smoke coming from the engine compartment can be an indication of engine oil leaking or dripping onto a hot part of the engine, more than likely an exhaust component. The oil drip will cause blue exhaust smoke when burned. Other possible causes of blue exhaust smoke coming out of the engine compartment may be due to an intake manifold gasket leak, worn engine oil seals, head gasket failure, and/or dirty or non-functioning PCV valve.
