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The 2004 CR-V does not have a timing "belt" it has a timing "chain". Honda does not have a recommended service interval for the Chain, as these are replaced on a "need-to" basis, which on these engines, are few and far between. Seeing as there is no timing belt running the water pump, it to is replaced on a "need-to" basis (the water pump is replaced when a timing belt is replaced, just for "preventative measures" seeing as the labor is excessive to get to a water pump that is timing belt driven). The serpentine belt should be replaced when there is either excessive "glazing" (the belt is shiney on the flat side) or excessive crack lines across the ribbed side, and should be visual inspected at intervals of every 30,000 miles.