I do not have that "slapping" noise, but I have a "ZZZZZZT" sound from the engine bay, as the oil pressure needle goes up when I first start it. It stops as soon as the needle reaches "3", which is very quickly. It does it for about a second. The warmer it is outside, the less it does it. I do not recall it doing it when temperatures are above 80°. No idea.

@ any rate, if I had a nice MB like it sounds like he has, I would not run it for a second W/O a new chain/rails/guides.

When you "price" getting this done, be sure you ask how much more for the rails and guides and tensioner. I was told $500 when I asked about the chain replacement, but when I asked how much more for the rails and guides, the price went up about $300, because he said much more work was involved in replacing those. I think that is what steered me away from having mine replaced.... I was all ready to pay the $500, but that additional $300 was the kicker. I paid $1000 for the car and I was not about to pay $800+tax for this.