I changed mine on my 93 and drove it for about a month. Car would barely start one day, so I limped home to find that the timing belt had skipped a few teeth. Thankfully, no damage done, but what I forgot or didn't realize was the missing plastic U retainer that goes on the end of the hydraulic tensioner. I was told by a Volvo mechanic that this takes up the slack on the belt once you've released the tensioner (I still don't get the mechanical of how and I couldn't see any slack before). Anyway, my timing belt kit never came with one, so I stupidly assumed I didn't need it. Maybe others have driven without incidence considering I drove a month without a problem, but it might be something to look in to.