[tonton]

I often see guys worrying about smoke from their cars, and worrying that their engines may be shot.

Although it is true that a shot engine usually produces smoke, smoke is not necessarily indicative of imminent engine failure.

I picked this up from the MASTERPARTS website, and thought it may help in initial assessment of smoke:

It is always wisest to do a compression test as this not only determines the degree of leakage past the piston rings, but also highlights which cylinder is the worst. Similarly, a simple driving test may help determine whether the oil consumption is caused by the pistons rings or the valves and valve guides. If you can see smoke continuously flowing from the exhaust, worsening as the engine revolutions increase, you can accept the rings are mostly or solely the cause. If however the engine does not smoke when revved, then the rings must be deemed to be able to effectively seal the cylinders when under load.

Accelerate down a slight hill until you reach around 60 Kmh in a low gear (second or third), and then stop accelerating so that the engine slows down against its compression for about 5-8 seconds. Without changing gears, start accelerating quite heavily again and watch the exhaust. If a puff of smoke is discharged from the exhaust simultaneously with re-accelerating, the valve guides and/or valve seals are defective. The cylinders are under a vacuum during the de-acceleration period, and re-acceleration causes oil to be sucked through the excess clearance in the valve guides/seals into the combustion chambers where it is burnt, giving off the smoke signal.

Hope it helps.

Anton