I helped my nephew replace his oil pan yesterday and everything went smoothly until the end. He started it up and there was tapping sound in the pan. We were just about ready to drop the pan and he tried to remove the dipstick. It was stuck, so after mangling the stick and tube we found that the dipstick was the noise because we forgot to remove it before we started. Just a word of advice to those who get the pleasure of replacing an oil pan on a bird.