The timing gasket is responsible for sealing the timing the timing cover to the front of the engine block. It is designed to keep dirt and debris out of the engine. On engines with timing chains it allows for the flow of oil to lubricate critical timing components.

Typically the most noticeable sign of timing gasket failure is an oil leak around the engine timing cover. However you may he a knocking from the cover if it is loose. If debris has enter the timing area you may have a rough idle condition. Sometimes a check engine light may illuminate. The timing cover gasket should also be replaced anytime the the timing cover is removed or when timing components are serviced.