It is vitally important that the timing chain is kept taut and in position. If it were to work loose it could wobble about and possibly jump; this would affect the engine timing and might result in the valves making contact with the pistons, which could result in catastrophic engine damage. To ensure this scenario does not happen, a timing chain guide rail constrains the chain and ensures it maintains the optimum level of tension. It is possible for the timing chain guide rail itself to become loose or even break, which would put the timing chain in a precarious position. Check your guide rail frequently, especially if it is making a noise, as this could be an indication of a slackening chain. Make sure you replace a damaged timing chain guide rail with one of the highest quality to prolong its life.