Just picked up another Volvo, making us a two Volvo family, so I figured it was time to join some sort of enthusiasts community.
Current stable includes:
2001 V70xc - The wife's car. Unquestionably the most comfortable car I've ever driven, but has developed a hissing under the driver's side footwell that needs addressing.
1995 850 turbo sedan - My new road warrior. I drive 110 miles a day to work and back, and needed a fuel efficient-ish, comfortable freeway cruiser. Found this with 136k, and all the important maintenance done for $2500 and jumped at it. So far I'm in love, but front passenger strut mount is shot, so I've got that to tinker with too.
Past vehicle history does include a 1980 something 240 dl, with close to 300k. Feaures included a spark plug someone had cross threaded so completely I couldn't remove it, so it was effectively a three cylinder, drivers seat so brokedown you could feel the floor boards, and a custom taxi spec beaded seat cover. What'd I pay for all this you ask? 24 room temperature Miller High Lifes, I say. But this was in 2000ish, so adjusted for inflation I suppose it cost me a 30 pack.
Aside from Swedish steel, I'm a union electrician (IBEW local 280), I shoot/reload, make beer, play (terrible) golf, and have kids.

 

does the hissing always happen or does it go away when you step on the brakes? if it goes away when you are on the brakes then the brake booster will need to be replaced. the diaphram inside those things brakes causing a vacuum loss or the hissing that you are hearing.
as for the 850 the strut mounts are really easy to replace as long as you have a spring compressor with you.

 

Hi and welcome to the forum.