The mechanic is currently doing the timing belt on my gf's 740 16-valve. I went by and looked at it and realized it's the early version (the cover was off, and I could see it was a spring-type tensioner). I know that the spring tensioners are 163 teeth, while the auto-type tensioners are 167 teeth. The mechanic is a general mechanic, not Volvo by trade, so I doubt he'd know the difference when ordering parts (and since the car is an auto, if the breakdown in the computer said B234-manual vs. B234-auto, he probably went with the auto since the car is an automatic).

So, if it is indeed the wrong belt, is it a serious problem? Would a length difference of 3 teeth make a difference? When I saw the car, the belt was tensioned on very tightly, and he actually had to undo the tensioner because the bearing made noise at start-up. Is there a possibility the belt is going to be too loose or the timing will be off?