Noises in the tower

…but before you get too worried, check and see if the crankshaft has been hitting the dipstick. Either the stick will be shorter than it should be, or you'll feel it getting hit if you put your hand on it with the engine running (and the noise will go away if you take the stick out of the engine).

If this is the problem, carefully bend the top of the dipstick tube slightly inward toward the block. Replace the dipstick if necessary.