White smoke: White smoke is caused by water and or antifreeze entering the cylinder, and the engine trying to burn it with the fuel. The white smoke is steam. There are special gaskets
head gaskets are the primary gaskets) that keep the antifreeze from entering the cylinder area. The cylinder is where the fuel and air mixture are being compressed and burned. Any amount of antifreeze that enters this area will produce a white steam that will be present at the tailpipe area.

If white smoke is present, check to see if the proper amount of antifreeze is inside the radiator and the overflow bottle. Also check to see if antifreeze has contaminated the engine oil. You can look at the engine oil dipstick, or look at the under side of the engine oil filler cap. If the oil is contaminated with antifreeze, it will have the appearance of a chocolate milkshake. Do not start the engine if the oil is contaminated with antifreeze, as serious internal engine damage can result.

How did antifreeze get in the oil or cylinder in the first place? The engine probably overheated and a head gasket failed due to excessive heat, thus allowing antifreeze to enter the cylinder (Where it is not meant to be).

Blue Smoke: Blue smoke is caused by engine oil entering the cylinder area and being burned along with the fuel air mixture. As with the white smoke, just a small drop of oil leaking into the cylinder can produce blue smoke out the tailpipe. Blue smoke is more likely in older or higher mileage vehicles than newer cars with fewer miles.

How did the engine oil get inside the cylinder in the first place? The car has many seals, gaskets, and O-rings that are designed to keep the engine oil from entering the cylinder, and one of them has failed. If too much oil leaks into the cylinder and fouls the spark plug, it will cause a misfire (engine miss) in that cylinder, and the spark plug will have to be replaced or cleaned of the oil. Using thicker weight engine oil or an oil additive designed to reduce oil leaks might help reduce the amount of oil leaking into the cylinder.

Black Smoke: Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

How did the fuel get into the cylinder in the first place? Some of the causes of excess fuel are a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or computer sensor. If black smoke is present, check the engine oil as in the white smoke example to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil. Call your mechanic and advise him of what you have found.

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White smoke: White smoke is caused by water and or antifreeze entering the cylinder, and the engine trying to burn it with the fuel. The white smoke is steam. There are special gaskets
head gaskets are the primary gaskets) that keep the antifreeze from entering the cylinder area. The cylinder is where the fuel and air mixture are being compressed and burned. Any amount of antifreeze that enters this area will produce a white steam that will be present at the tailpipe area.

If white smoke is present, check to see if the proper amount of antifreeze is inside the radiator and the overflow bottle. Also check to see if antifreeze has contaminated the engine oil. You can look at the engine oil dipstick, or look at the under side of the engine oil filler cap. If the oil is contaminated with antifreeze, it will have the appearance of a chocolate milkshake. Do not start the engine if the oil is contaminated with antifreeze, as serious internal engine damage can result.

How did antifreeze get in the oil or cylinder in the first place? The engine probably overheated and a head gasket failed due to excessive heat, thus allowing antifreeze to enter the cylinder (Where it is not meant to be).

Blue Smoke: Blue smoke is caused by engine oil entering the cylinder area and being burned along with the fuel air mixture. As with the white smoke, just a small drop of oil leaking into the cylinder can produce blue smoke out the tailpipe. Blue smoke is more likely in older or higher mileage vehicles than newer cars with fewer miles.

How did the engine oil get inside the cylinder in the first place? The car has many seals, gaskets, and O-rings that are designed to keep the engine oil from entering the cylinder, and one of them has failed. If too much oil leaks into the cylinder and fouls the spark plug, it will cause a misfire (engine miss) in that cylinder, and the spark plug will have to be replaced or cleaned of the oil. Using thicker weight engine oil or an oil additive designed to reduce oil leaks might help reduce the amount of oil leaking into the cylinder.

Black Smoke: Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

How did the fuel get into the cylinder in the first place? Some of the causes of excess fuel are a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or computer sensor. If black smoke is present, check the engine oil as in the white smoke example to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil. Call your mechanic and advise him of what you have found.

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A timing belt, or cam belt (informal usage) is a part of an internal combustion engine that controls the timing of the engine's valves. Some engines, like the flat-4 Volkswagen air cooled engine, and the straight-6 Toyota F engine use timing gears. Timing belts replace the older style timing chains that were in common usage until the 1970's and 1980's (although in the last decade there has been some reemergence of chain use). The term "timing belt" is sometimes used for the more general case of any flat belt with integral teeth, although such usage is a misnomer since there is no timing or synchronization involved.


Engine applications

In the internal combustion engine application, the timing belt connects the crankshaft to the camshaft(s), which in turn controls the opening and closing of the engine's valves. A four-stroke engine requires that the valves open and close once every other revolution of the crankshaft. The timing belt does this. It has teeth to turn the camshaft(s) synchronised with the crankshaft, and is specifically designed for a particular engine. In some engine designs, the timing belt may also be used to drive other engine components such as the water pump and oil pump.

Gear or chain systems can also be used to connect the crankshaft to the camshaft at the correct timing. However gears and shafts constrain the relative location of the crankshaft and camshafts. Even where the crankshaft and camshaft(s) are very close together, as in pushrod engines, most engine designers use a short chain drive rather than a direct gear drive. This is because gear drives suffer from frequent torque reversal as the cam profiles "kick back" against the drive from the crank, leading to excessive noise and wear. Fibre gears, with more resilience, are preferred to steel gears where direct drive has to be used. A belt or chain allows much more flexibility in the relative locations of the crankshaft and camshafts. Timing belts or chains are also able to even out wear, since they can be made such that the number of teeth on the belt is coprime to the number of teeth on the crankshaft and camshaft sprockets, thus ensuring that each tooth on sprocket does not end up on the same tooth on the belt repeatedly.

While chains and gears may be more durable, rubber composite belts are quieter in their operation (in most modern engines the noise difference is negligible), are less expensive and are mechanically more efficient, by dint of being considerably lighter, when compared with a gear or chain system. Also, timing belts do not require lubrication, which is essential with a timing chain or gears. A timing belt is a specific application of a synchronous belt used to transmit rotational power synchronously.

Timing belts are typically covered by metal timing belt covers which require removal to carry out visual inspection. Engine manufacturers recommend replacement at specific intervals.[1] The manufacturer may also recommend the replacement of other parts, such as the water pump, when the timing belt is replaced because the additional cost to replace the water pump is negligible compared to the cost of accessing the timing belt. In an interference engine, or one whose valves extend into the path of the piston, failure of the timing belt (or timing chain) invariably results in costly and, in some cases, irreparable engine damage, as some valves will be held open when they should not be and thus will be struck by the pistons.

Indicators that the timing chain may need to be replaced include a rattling noise from the front of the engine.[2]
Timing

When an automotive timing belt is replaced, care must be taken to ensure that the valve and piston movements are correctly synchronized. Failure to synchronize correctly in an can lead to problems with valve timing, and this in turn, in extremis, can cause collision between valves and pistons in Interference Engines. This is not a problem unique to timing belts since the same issue exists with all other cam/crank timing methods such as gears or chains.
Failure Modes

The usual failure modes of timing belts are either stripped teeth (which leaves a smooth section of belt where the drive cog will slip) or delamination and unraveling of the fiber cores. Outright snapping of the belt, because of the nature of the high tensile fibers, is very uncommon.[citation needed] Correct belt tension is critical - too loose and the belt will whip, too tight and it will whine and put excess strain on the bearings of the cogs. In either case belt life will be drastically shortened.


Construction & Design

A timing belt is typically rubber with high-tensile fibres (e.g. fiberglass or Twaron / Kevlar) running the length of the belt as tension members.[3]

Rubber degrades with higher temperatures, and with contact with motor oil. Thus the life expectancy of a timing belt is lowered in hot or leaky engines. Newer or more expensive belts are made of temperature resistant materials such as "highly-saturated nitrile" (HSN).[citation needed] The life of the reinforcing cords is also greatly affected by water and antifreeze. This means that special precautions must be taken for off road applications to allow water to drain away or be sealed from contact with the belt.

Older belts have trapezoid shaped teeth leading to high rates of tooth wear. Newer manufacturing techniques allow for curved teeth that are quieter and last longer.


Aftermarket timing belts may be used to alter engine performance. OEM timing belts "will stretch at high rpm, retarding the cam and therefore the ignition."[4] Stronger, aftermarket belts, will not stretch and the timing is preserved.[5] In terms of engine design, "shortening the width of the timing belt reduce[s] weight and friction".[6]


Usage History

The first known timing belt was used in 1945.[7] The German Glas 1004 was the first mass produced vehicle to use a timing belt in 1962. The first American vehicle to use a timing belt was the 1966 Pontiac Tempest. In 1966, Vauxhall started production of the Slant Four overhead cam four-cylinder design which used a timing belt, a configuration that is now used in the vast majority of cars built today.

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