Hello. After getting a $900 estimate for changing the timing belt on a 2005 S 80 T-5 engine with 113,540 on it, I'm suddenly interested in doing it myself. It's going to be a deep change with a new water pump. I may buy one of those tools that locks the two valve pulleys in the correct position as new valves ( should I fail ) cost $67 each and there are 24 of them. My question is: How do you adjust the belt tension ? Are there any tips that can save me from any aggravation? I have looked at the pulley/jockey wheel with the allen wrench thing that is turned back to adjust tension but to what point? Do I put the belt on , turn over the car a couple of times and check tension? Is there a torque value?

Any thoughts , things not to do or things to do are appreciated. Thank You