What does the timing chain do? The timing chain is a metal chai? as opposed to a timing belt which is made of rubber. The chain is located inside of the engine and needs to be lubricated by the oil in the engine so everything runs together. It keeps the crankshaft and camshaft(s) in good timing with each other. This insures proper operation of the engine. In some vehicle? the timing chain also runs other components of the vehicle like the water pump. How do you know you need your timing chain replaced? Loss of power while vehicle running indicating timing chain or tensioner failed Vehicle has rough idle or shakes vehicle doesnt start Engine light is on and shows a timing code How is the timing chain replaced by a mobile mechanic? Remove engine cover and other accessories to gain access to chain In some vehicle? The front of the vehicle including the bumpe? radiator and hoses have to be removed to gain access Remove and replace timing chai? tensioner? guides and accessories (if equipped) Line up chain with marks on camshafts and chain Re-attached cover and any accessories that were removed Test drive vehicle How important is having your timing chain replaced? The timing chain is under high tensio? if the chain break? stretches or if the tensioner fail? it can cause serious internal damage to the engine. This component should not be overlooked and should be replaced as scheduled.If one of the timing components fail? its highly recommended to change all timing components such as chai? tensioner and all guides.