I just did the timing belt on my new used 1996 850 GLT Wagon. It took some time, but was not that difficult. I found it harder to change the serpentine belt, it is so tight!
Some tools required: metric sockets, 30 mm socket to turn crankshaft.
torx bits, 25mm, (30 mm-to remove plastic cover over spark plugs I'm not sure why this is necessary).
On mine, to release belt tension on the serpentine belt, you need a 3/4" square drive adapter - or, per someone elses suggestion here on the brickboard, I made my own tool out of 1/8" thick steel plate, cut out 1" x 1.25" section, 1" section going into the tensioner on the diagonal, used large pliers (adjustable wrench would also work) to grip this piece and rotate the belt tensioner all the way until you can pin a nail thru the holes that holds it in the untensioned location.
I followed the volvospeed.com instructions. The timing mark on the crankshaft pulley is on the timing belt drive pulley, a little 'V' cut into a tooth, nearest the engine side of the timing belt crank pulley. It is very small, I could easily see the other marks on the camshaft pulleys. I was able to work the new belt in behind the crank pulley without having to remove the pulley to get the new belt on.
You need a 7" vise to compress the hydraulic tensioner slowly, over 10 to 15 minutes. I stuck a nail with the end bent 90 deg. to aid in pulling it out quickly once its reinstalled.
Just make sure you double check your timing marks line up by hand cranking the engine once or twice and reinstall the top cover to verify the marks are OK.
Then cross your fingers the first time you start the engine. I was pretty confident I didn't screw anything up and it worked out fine. Cost me $50 to do it myself, not including a new serpentine belt. Took me probably 8 hours - but I'm real slow, took breaks, spread it out over two days - wasn't really in a rush. I would say I now could do it again in half that time.

I've seen posts from $270 to $350. I just purchased the belt from
volvoparts.com for under $40 so the cost is mostly labor (and that
means it varies greatly by where you live).

I plan to do it myself on a sunny day (they say you need lots of light).

Note that messing it up can destroy the engine (there is a post below
where that happened to the owner).

By the way, the belt is much smaller and thinner then I imagined (I
now have the parts). I was surprised it is not "beefier".

volvo speed.com my friend that why we all here.... let us know how long it take you and what you think.... I think it is a cake walk just take your times and relax with a cool beer.... steep by steep it not that hard....


go for it do it on a weekend so you don't have to rush...... and this way you also get to know your car......

my dealer quoted me 300-315.

Dan

I have a 95 850 and it cost me $1,000 to get my belt changed. The dealerships try to find everything possibly wrong with your car and then they bill you. My advice to you is do it yourself. I found out about bay13 after I had my belt replaced. Had I known about it, I think I would have done it myself. IPD sells the belt you need and I think some simple tools as well.
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Drew

You'll get all kinds of answers to the "should I do it myself question." Do a search here for timing belt info and look at www.volvospeed.com and the bay 13 instructions on how to do it. I did it myself, as have many other members here. If you take your time and do it properly, no problem. Rush and it can cost you an engine. I think around $350 or so is the going rate to have it done. Good luck and let us know what you do. There are no special tools required BTW.

www.volvospeed.com