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Engine knock/tap

Hi, I have an '05 Subaru Outback, 40K miles, auto transmission. When the engine is warm, I hear a tapping/knocking nose when car is in gear, but idle. I’ve taken it to a couple mechanics, and unfortunately the car hasn’t performed for them so no one knows what’s going on. Anyone have any ideas?

Maybe loose bolts or a crack in the flex plate. Checking means seperating the engine and trans. I would wait until it gets worse and steady.

Where is the noise coming from?
Is the frequency of the noise in synch with engine speed (if you race the engine, does it tap faster?), or is it a constant rhythym, or is it more random?

If the noise is a random one coming from underneath the car, it is likely just uneven expansion of some of the components in the exhaust system.