'88-924S

Okay, had belts replaced about 25k ago w/ 41K orig. miles. I had a temp problem, and replacing grounds fixed that wonderfully. Now my car never goes over the 1/2 mark for temperature. But my coolant has been disappearing to somewhere. After hours going through archives I've pretty much decided that my WP seals are leaking which is a precursor to WP failure, right?. However, I'd like to see if I can listen to WP with a screwdriver, archives say listen for whining/clicking from WP, but we all know the mechanical sounds the valves make.
My question-what will I hear when putting my ear to screwdriver to WP if it's alright? If WP is failing what will I hear? Will it be obvious? For safetys sake I'm sure I'll just do the belts/WP, seal replacement, but I'd like to get some knowledge so that next time I can trace this potential failure next time.
Thank you everyone for all responses. No superflous thoughts here, give me your experience or ideas on this.
Let's keep these WPs from bumming anyone else out by destroying valves.