SMOKING is a bad habit. Smoking cigarettes in your car is also a bad habit. Besides the health risks, there’s also the risk of burning holes in your nice upholstery and leaving smokey cigarette smells behind.
However, there is another type of smoke that even non-smokers suffer from. A smoking exhaust tailpipe.
You may notice on cold mornings that your exhaust tailpipe is emitting smoke (or what looks like smoke). After the car has warmed up, the smoke disappears. If this is the case, worry not.
A by-product of combustion is water and it collects in your exhaust pipe and muffler. A car warming up will evaporate the water and emit the “smoke” that you see. But there are times when the smoke just does not go away.
If you car has thick smoke coming out of the exhaust pipe, it is a sign that your engine needs some attention. The type, colour and smell of the smoke as well as the driving conditions it occurs at will indicate what problem your car may have.
The symptoms below are the most common:
BLUISH OR GREYISH SMOKE
Grey smoke (sometimes with a bluish tint) coming from the exhaust when you start your car in the morning, which may disappear after a short while, may indicate a problem. Even if the smoke disappears, check that there is no smell left behind. Smoke with a bluish tint to it that disappears may just be an indicator that the engine’s piston rings, valve seals or valve guides may be on the verge of wearing out.
The smell of burning oil may be faint but the real test is if the engine is burning more oil than normal (some cars burn oil naturally, but at a very slow rate). If the dipstick indicates a drastic change in oil levels that means that the car is burning oil even if the tailpipe may not visibly smoke.
Check for oil leaks from the engine before coming to a conclusion, however. Another indication is a slight drop in engine power. Fixing this problem requires a full engine stripdown and replacement of the offending parts.
A competent foreman may be able to perform a compression test to see if an overhaul is necessary before you commit to it.
A test you may perform to confirm which parts are worn is to use the rear view mirror. If you notice the smoke in your mirrors as you decelerate (after accelerating fairly hard) the culprits are in the valve train, i.e. valve seals and/or valve guides.
A car with worn piston rings will smoke heavily under hard acceleration, which means a bigger repair bill.
If your car smokes under both instances, you will have a bigger repair bill. It is easier to have a friend to observe the incidences (if you are not confident) as using the rear view mirror while driving alone may result in an accident (and a big, big repair bill).
White smoke when you first start your car may be the aforementioned water. If the weather is especially cold and there is no smell of burnt oil, this is normal.
If the smoke does not disappear after the car has warmed up, you have a few problems.
If there is a distinct burnt oil smell, you may have transmission oil entering the intake manifold through the vacuum modulator. Replacement of the vacuum modulator is simple and cheap.
If there is a different sort of smell, it may be that the cylinder head gasket is failing. Check your coolant levels to confirm this. Repair involves a top end overhaul to replace the head gasket.
BLACK OR DARK SMOKE
Black smoke from the exhaust is bad news. It may disappear after warming up and be less noticeable but it will need to be addressed.
The engine may or may not be running rough or misfiring. Possible causes is that the choke may be stuck closed (an easy fix) or the air filter is seriously clogged (also an easy fix). But if the two items are okay, you may have an ignition problem (that is easy to fix on older cars).
Replacement of parts such as the ignition coils, distributor, condensors or contact points on older cars are easy and quite cheap but on a modern car, it may involve a pricey ECU replacement and/or tuning to suit.
A definite symptom of this smoke is a tendency for the car to use more fuel than usual, burn out spark plugs regularly and a general lack of power.
Other things to check are the ignition timing (on older cars). A leaking head gasket may also be indicated by a drop in coolant level and subsequent overheating. Partially stuck injectors as well as a faulty fuel pressure regulator may also create black smoke. Your foreman will be able to diagnose and troubleshoot the problem.
Diesel car owners may feel left out but the same still applies since newer diesel cars tend to emit very little smoke. Turbocharged car owners have more items to go wrong and smoke is usually a bad sign for the health of the turbocharger unit.
In conclusion, anytime you see smoke in your tailpipe is a bad sign for the health of your wallet. Unless you own a two-stroke Saab, of course.