My timing belt broke while driving, the manuel I have shows replacing a unbroken belt and does instruct where the crankshaft is in relation to the intake and exaughst gears.
Many engines are “interference engines”, which means that there will (very likely) be internal engine damage when the timing belt breaks. To find out if there is damage, usually bent valves, a cylinder leakdown test can be performed. Bear in mind that some mechanics can’t/won’t perform a leakdown test. The test takes tools, know-how, and willingness.
After you establish if internal engines repairs are needed (or, not), and done, you can carry on with the timing belt change.
For us to determine if the engine is an interference engine, we need to know the model year of your car and the engine size.
All Volvo 960s with the 2.9L V6 are interference engines, and there’s a great chance that engine damage has occurred. This will cost a lot more than a new timing belt.
That being said, to time the new belt, the crankshaft must be rotated to TDC (top dead center), where the timing mark reads a 0 deg. Then, the marks on the camshafts are lined up with corresponding marks as shown in the shop manual. This will set the proper camshaft timing to match the crankshaft timing. The belt goes on, the tension is set, and the crankshaft is them rotated two full rotations, back to TDC, and the marks checked again. If the marks are off, further adjustment is required. If the marks line back up, your good to go. Doublecheck all the bolts are properly torqued and your done.