Hi all. Have a few probs with a 81 hj47 2h. I inherited the ol girl and went for a drive the other day and there was a bang when I was driving and a loud tapping noise got it back home and had a look and all looked good starts and idles great blows a bit of smoke at idle The tapping noise comes and goes. Don't really know what the problem is. Any advice would be helpful as I not really up to speed on Diesels