Bob-

I can replace the timing belt on your car in about 30 minutes- with a hoist, compressor, and the tools I have accumulated during my career as a Volvo Master Tech. There are two versions of belt tensioners, one that takes a special tool (some use a vise to compress this style- not recommended by myself) and the other uses hand tools to set the tension. It is probably in the realm of the do-it-yourself car owner with reasonable mechanical ability, but be forewarned of the consequences of botching the job. There is a possibility of CATASTROPHIC ENGINE DAMAGE in the form of bent valves. If this engine experiences piston-to-valve contact, the cylinder head must be replaced. This is a very expensive repair, to say the least, and is definitely beyond the capabilities of even some Volvo independent shops. If you prefer to attempt the job yourself (timing belt) I recommend (strongly) that you go to the dealer and get someone to print out the procedure from the VADIS info. It has pictures and specs along with the recommended step-by-step replacement for the belt.