I've seen a lot of threads on belt slap with no resolution. So I figured I'd post something I faced today, and how I fixed it.
Well I figured out how to replace the tensioner pulley and bypass the tensioner for now. It was causing a chirp and vibration at idle that became noticeable after a transmission replacement. That will be the subject of a video in the next few days. It's easier than you think if you got the right $20 tool. Now the busted torx bit inside the tensioner bolt is another story.
That's when in my cars classic fashion in finding new improved ways to frustrate me and the poor souls who work on it, it decided to throw the belt
. The reason was the belt had a small wear pattern on it that I couldn't quite see on the back anytime I inspected it. After kicking myself and on inspection of the old belt I cold see exactly where it slid. So when it hit the new pulleys it just flipped right off. So I remove the belt, inspect everything and clear it. I go get my new Dayco belt. And it makes a slapping sound
. An hour later after a long mental break, I track it to the idler alternator area. I shut the car off loosen the belt, recheck the pulleys and looking down right in front of me I find a large bump on the belt. I looked at the belt and didn't see anything, but dust had make it visible.
40 minutes later- New Duralast belt, no chirp, no squeak, no slap. According to the manual slap means lack of tension, something's touching the belt, or the belt has a defect.