O2 sensor and white smoke

[FJB203 at aol.com]

In a message dated 97-02-03 11:27:50 EST, you write:

> Is the O2 sensor supposed to replaced as part of regular maintenance and if
>  so, how often?

Well, that depends.  Most passenger manufacturers say they will last 100k.
 Of course, if you have a turbo or the engine runs really hot all the time,
they cook sooner.  I generally have replaced them as a last resort when the
car doesn't run that well, and I've replaced plugs, filters, plug wires, etc.

>  Also, let's talk about causes for white smoke. Not thick and bellowing but
>  visible from behind during heavy acceleration from by high mileage 302HO.
I
>  was told by a friend that it is frequently caused by valve seals. I
thought
>  that leaking valve seals was mostly evident during starting by blue smoke!

Blue smoke means you have oil in your combustion chambers, typically caused
by poor piston ring seating (either installed incorrectly, or more common -
worn out).  White smoke definately can come from the valves not opening and
closing all the way or at the right time, however you might want to check
ignition coil spark voltage.  Sometimes a hotter spark can clean that up.

Fred