Thanks Klaus/Bob, i started to pull things apart and the tensioner has totally disintergrated, the belt flapping in the wind on the right side reaffirming how lucky i am that the car did not expire on 18yr old on the highway on his way to uni. The section of the belt cover that has the reference points for the cam gear marks has of course been cut off by the sliding belt (dang) and i have replaced the tensioner etc on the other halves 850 but have had no experience with a mechanical tensioner. So two things: any clues as to fitment and any diagrams of the tensioner in place on the engine. And while we are at it, what is the purpose of the pin that causes so much pain in the belt removal underneath the crank pulley? Looking forward to your replys. Thanks David

Because you no longer have cam reference marks, here is what should be done - minus going to the pick&pull to get a new top cover.

Remove the spark plugs to make turning the crank easier. Find the crank pulley timing mark and paint it with white out so it is easy to see. Turn the crank until it is TDC and check the cam marks. The cams should point to about 11 and 1 o'clock at TDC, turn the crank another 180 degrees if not close.

Find something, like a Tsquare to mark the cam positions against. Because the belt hasn't slipped off, count the teeth between the cams.

The plate under the crank sprocket keeps dirt from splashing agains the belt. The pin is there to keep DIY'ers from having an easy time of things.

As for the tensioner, I could not find good pics for the 5 cyl. I did find one for the S40 which looks real good. Just scroll down a few pages:
http://volvospeed.com/volvo_repairs_how_tos/engine_repairs/volvo_replace_timing_belt.html

The adjustment procedure is here:
http://volvospeed.com/volvo_repairs_how_tos/engine_repairs/manual_tensioner_adjustment.html

I know, nothing is that easy!

Klaus
--
Volvos should be saved from the junk yards, not donated.