That’s normal; that’s why there is a bracket to hold it more or less still. I’d do this, get some large wood plugs from a marine store, when you disconnect the long hose that goes from the transom mount to the impeller housing hold it up in the bilge & plug it. That hose is below the static water line & water WILL flow into the boat if you don’t plug it. I think that hose internal diameter is about 1-1/8” or so. I have replaced the thermostat on my OMC cobra a few times exactly this way. You won’t get much water out of the other hose from the impeller housing only the long one from the transom mount.
However first I would:
Remove serpentine belt
Get a straight edge like a mechanics straight edge or a carpentry level.
Remember that everything is turned by the crankshaft pulley. So lay the straight edge across the crank pulley and then see if the power steering pulley & alternator pulley line up. If not got to find out why. Spin each pulley feel for wobble & looseness. The bearings in the p/s pump, the alternator and water circulating pump can all go bad. Also they can actually seize up if the bearings fail. Don’t forget to check the pulley on the belt tensioner.
I know that some Volvo engines had trouble with the bracket for the alternator or P/S pump flexing or bending throwing off alignment.
I actually prefer the old fashioned V belts; no trouble with them & if one breaks at least the other still works. If the p/s or alt belt breaks on mine I still have the other to spin the front circulating pump. Yep you have to tension them by hand but with the right tools (pulley spreader jack) not a big deal.
Google Volvo Penta serpentine belt jumps off someone else had that problem & fixed it….
