I agree and it sounds like the inline vacuum check valve for the brake booster came apart which is a not too uncommon occurrence especially if the it's the original check valve.

AFAIK, no one sells the exact correct inline check valve and that is Volvo's fault.

Volvo updated the brake booster check valve, but to a vacuum check valve used on 240/260. And although functionally the same, the problem is that hose barbs on the updated check valve are smaller than the original.

You can use that valve, but it requires that you over-tighten the hose clamps on brake booster and that will shorten the life of the hose.

When I discovered this problem 30 years ago, I found another check valve made by the same manufacturer that has the correct sized hose barbs.


--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com