The main similarity in the timing chain and a timing belt is that both parts rotate the camshaft. Both are visible when you open the hood, hidden behind metal or plastic timing covers. As the name states, they keep the camshaft in-time and safe no matter what conditions are evident in the engine. That is all the similarities, considering an average price of a timing-chain is $75 in comparison to an $800 belt-drive kit. As you will see, a mechanic is the one that can be instrumental in decisions on the differences of the two.
Most cars on the highway have four-stroke engines because the engine has compression, intake, power, and exhaust stroke involved in the combustion process. During the process, the camshaft/camshafts will spin once, and the crankshaft will rotate twice. The correlation between the rotations of the camshaft/camshafts is called mechanical timing. This is what controls the movement between the pistons and valves inside the cylinders. Therefore, the exhaust and intake valves must open precisely in time with the pistons. Without this timing, the engine will not run.
Replacement will be required for timing chains only if a problem occurs whereas replacement is required for timing belts at specific intervals. Timing chains require less frequent and less costly maintenance unless the chain, tensioner, or guides indicate a problem. If this occurs, it will require the engine to be broken-down, and will be much more costly than a timing belt replacement. In some cases, the engine may need to be removed for repairs.
Timing chains can loosen or stretch whereas belts remain tight without damaging the belt teeth until they snap. Chains require an oil bath, but belts do not require any special lubricants. Chains are stronger and can often be used to drive more than just the cam with the timing chain. Due to stretching, a timing chain replacement includes changing all the timing gears since the teeth will not match. This is not essential for a timing belt, but it is recommended to replace the gears and idlers.
Timing belts are chosen by car manufacturers as a more economical choice. It is estimated to replace the belts every 40k miles. The belt will whine before it breaks as a safety feature, so you will know it is time for servicing.
Timing chains should be replaced approximately every 100k miles or when rebuilding. It will begin rattling, indicating the chain has stretched.
This information should help you with understanding the differences between the timing belt and the timing chain. It is recommended to inspect the vehicle before you make the purchase. Leave all the difficult choices up to a qualified mechanic that works with vehicles for a living. Contact a company like Foley Auto & RV Repair for more information.