This entire operation happens hundreds of times per minute. The valves must open and close at precisely the right time. The intake and exhaust valves are activated by the camshaft, which has lobes that push them down to open and then let off so they spring back to close. Depending on the engine, there will be one, two, or four camshafts. There are sprockets at the end of the crankshaft and camshaft, and the timing chain or belt is attached to them.
On most engines, it also operates the water pump, which circulates coolant through the engine and radiator. A timing chain is exactly as it sounds — it looks a lot like a bicycle chain — while timing belts are usually made of reinforced rubber compound. Chains, which used to be the only choice, are stronger and more durable.
But many older vehicles still have them, and may now be near their recommended replacement, which is usually around , to , kilometres. The rubber belt you see under the hood is the serpentine belt, which runs such components as the alternator and air conditioning compressor.
But if the timing belt breaks, piston and valve can meet, resulting in expensive damage that, in the worst-case scenario, may require a new engine. Automotive timing belts then and now are made of rubber, often with fiberglass or Kevlar woven into them for extra strength. Timing belts are known to be very quiet as they rotate, but they do wear out over time. Most vehicle manufacturers recommend changing timing belts between 60, and , miles, though there are exceptions, both higher and lower.
Because timing belts frequently move through pulleys and have hydraulic timing tensioners applying tension on the belt throughout the entire rpm range, these mechanical and hydraulic tensioners and pulleys should always be replaced at the same time as the belt. They are all the same age with the same mileage, so replacing them is a great habit and great insurance. Along with pulleys and belt tensioners , water pumps are often replaced at the same time as timing belts.
This is for two reasons: Some water pumps are actually driven by the timing belt itself, and are therefore a liability if they are old and worn out. The other reason is because many water pumps, especially on newer vehicles, are tucked behind the timing belt due to packaging constraints.
You wouldn't want to replace the timing belt and then have to take it off again later when your old water pump fails. Doing the job twice is never fun. A timing chain looks just like a bicycle chain, but much cleaner. Like the timing belt, they connect to the camshaft and crankshaft and help keep the engine timed.
The beauty of the timing chain is that it typically lasts a very long time. The downfall of timing chains is that they are heavier, generally known to be noisier, and if they do break it is usually catastrophic to all of the surrounding engine parts.
Some car manufacturers recommend replacing it at certain mileage or time intervals, while others claim that the chain does not need to be replaced for the life of the automobile. It really depends on the make and model of the car or truck. Much like automotive timing belts, timing chains have tensioners that keep the chain from flopping around.
The difference is that timing chain tensioners are nearly always controlled with the engine oil pressure. As you can imagine, if the engine oil pressure becomes low for whatever reason, the oil-driven timing chain tensioners will lose pressure and the mechanical engine timing will offset.
This will cause poor engine performance and give the chain an opportunity to fail in grand fashion. The other benefit to timing chains is that they rarely have anything to do with the water pump, so replacing them at the same time isn't nearly as necessary as it is with a timing belt.
As with everything in life, there are exceptions to this rule. Luckily, your car probably isn't one of them. You can't talk about timing belts and chains without talking about interference engines. First off, not all engines are interference engines. Some car and truck manufacturers have them and some don't. It is hit or miss thing depending on the vehicle.
This could cause some pretty expensive damage, unless you got really lucky and the timing belt broke in a position where there was no contact. In this case, you can try replacing the timing belt and see what happens.
My timing chain went on my beetle while the mechanics were working on it they found that my camshaft had too much give and should also be replaced. Car was purchased CPO and I still have 14 payments left. Should I repair car or roll the remaining balance into something new with a warranty? That is completely up to you. On the other hand, your mechanic needs to be really honest with you about the current state of the vehicle. If he or she foresees many problems in the near future, it may be best to cut your losses and find a different vehicle in better condition.
Had the top timing chain on bmw go when at a red light …. That one is an interference engine, right?
If so, there is a very strong possibility that other components were damaged when the timing chain let go. The car could probably run again, but it depends on how much effort and money you want to put into it, and the extent of the damage.
It looks like the timing chain on my Kia Sorento broke. Slight smell like something burned. Took to a local mechanic and he inspected it not a deep dive but said it looks like the timing chain. What causes a timing chain to break or wear? How important is oil quality? Should I replace the accessory drive belt when replacing a timing chain? Cloyes Tech Tips: Ford 3. Cloyes Tech Tips: Chrysler 4.
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