Why am I hearing a knocking sound from my engine

My 2004 frontier is making a knowing sound from the engine, i thought it was the timing belt but it wasn’t

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how many miles are on it? Did you check the oil? What else have you checked so far besides the timing belt?

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I checked the oil, power steering pump and the mileage is at more than 200,000 but a friend of my checked it he said it was the idler bearing

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