Try this link for pictures and instructions

http://www.volvospeed.com/Repair/airpump1.htm

25 minutes to replace the SAS Check Valve and the airpump. Not very Difficult I did it in a rain storm(4inches of rain in 3 hours) 2 weeks ago. Dealer wanted $650 If I remember correctly.

Parts and their numbers for an 86 non turbo

Airpump 1270558 About $241
SAS (check Valve) 9125623 Both valve and Gasket Around $90
SAS Gasket 1271764
Clamp X 2 978176
Clamp x 1 977965
Clamp x1 980613

The Clamps I just used worm drive hose clamps and for the small vacumn line I used a ZIP tie.

I ordered from the site below and talked to Eric 1-888-628-3247 EXT 309

http://www.alloemvolvoparts.com/volvo-maintenance.html

Try this link:

http://www.volvospeed.com/Repair/airpump1.htm

Problem originates in the air valve associated with the air pump, so make sure you change the air valve along with the several-hundred-dollar pump, or your going to be buying another pump very shortly.

Not difficult to change, but I've found that the easiest way is by removing the battery and the battery box. Takes a little longer, but you have greater access than working on your back from below.

Watch out. Lots of vacuum lines there for the cruise control. They slip off of their connectors very easily, so if you notice that your cruise control doesn't work after you've done this replacement, you probably lossened one of these things.