I am in the middle of the timing belt, water pump, thermostat replacement on the 2000 300M: I got the new belt on, all 3 marks lining up and when I tighten down the tensioner bolts (haven't released the cotter pin yet) both the cam timing marks moved a tooth to the left. I started over and moved them back to where I started (crank mark stayed at tdc). I can hand tighten quite a bit and have them stay, but they seem to stray with the tensioner tightened down. Is there a guideline for how to check how much tension should be on the belt before pulling the pin? I can't get a torque wrench in there either so the 250 in/lbs. doesn't help.

Any thoughts appeciated.

 

release it then turn the crank until all the marks align back up if they are then u are good.