Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › How to diagnose brake master cylinder vs. brake servo/booster? › Reply To: How to diagnose brake master cylinder vs. brake servo/booster?
10 – 15 in of vacuum should be enough to check it for any leaks and no, no need to press the brake pedal.
Keep in mind if the was a leak in the brake booster, most likely you would have a harder brake pedal due to lack of vacuum.
One other item to check would be the check valve on the boosters vacuum hose.
- This reply was modified 8 months, 4 weeks ago by Richard Kirshy.