R.I.P Allan Simonsen
AO Silver Member
Join Date: Dec 2007
Location: United Kingdom
for the record, exhaust smoke can be easily identified with some of the following clues, starting at the top of the engine and working downwards
Valve stem seals - smoke on startup that clears almost instantly worse the longer the car stands, when idling for extended periods of time the exhaust gets progressively smokier. this will be a pungent blue smoke
Valve guides - puff on startup (sometimes) also usually smoke on gear change and deceleration, same colour and smelling smoke as valve stem seals.
head gasket - white pungent smoke, often changes as it gets warm (could get worse or better - usually worse) the change will be progressive though. with white smoke there will be a loss of coolant, with no obvious leaks. this is also often accompanied by rough running, an irregular sound on the starter motor, poor starting, an ECU warning light and overheating. the car may also have 'mayonnaise' under the oil filler cap and on the dip stick*
Rich mixture - black sooty smoke, this also tends to manifest itself as sooty deposits on the rear bumper, number plate and tail light. this will set an ECU light due to the o2 sensor detecting the change in exhaust gas, also likely to produce a very 'hunty' idle, if the regular idle is baaaaaaaaaa a rich idle would be ba ba ba ba ba, it sounds similar to an engine running on 3 cylinders.
bore wear - blue strong smelling smoke under acceleration - this also is often accompanied by significant 'breathing' from the oil filler cap when the engine is run without it (careful, this can be messy!) in extreme cases the dipstick can be ejected from its tube, and the car can become hard to start when cold - there will be a large increase in oil consumption with bore wear. (when a car has substantial bore wear you will be using a lot more oil than the handbook advises as normal - usually over 200,000 miles these days )
*mayo on the underside of the oil filler cap can also be due to a lot of short runs, especially with the twin spark engine.
if none of these associated symptoms are present, its most likely just condensation