Our MDX was the same way -- the rear cam, at 12:00 position on the timing mark, must be just BARELY sitting "in equilibrium". If you move it just a smidge either way, it'll snap over to the 4:00 position, or snap back to the 8:00 position. It scared the heck out of me when it happened, but there is no piston contact when that happens, and it seems to be just a part of doing the job.I did have one issue, don't know if anyone else did. When I took off timing belt the rear cam sprocket turned. I don't mean just a little I mean it jumped like it was under load. When I brought it back it would do the same thing the other way. Was a job keeping it right on the money.
It goes to show just how much stress and pressure is put on that timing belt, constantly being pulled one way or the other all the time. I look forward to doing our Ridgeline's timing belt job this spring.
I'm sorry to see that you're having water pump leaks. Did you get that straightened out? I know a couple of people who have used aftermarket kits who have had problems with *something*, whether it's the water pump, or tensioner, or something else. I did use OEM parts on our MDX's job, and I plan to do the same with the RL. It is certainly more expensive that way.