Originally Posted by WyrTwister
For the master cylinder , first look for leaks . If it feels " spongy " , it is bad . Other than that , not sure .
Brake booster , listen for leaks . Disconnect & plug the vacuum hose . Any difference in the way the brakes work / perform .
I am with you , with the miles on the vehicle , I would replace both , if in doubt . Check out rockauto.com . Other than OEM , I do not know which brand to avoid vs. purchase .
Best of luck to you .
Thank you so much! The brake pedal actually feels great right now, very responsive and no spongy feel. It always feels great until it suddenly doesn't at random with no warning. No fluid leaks. If I disconnect the brake booster the pedal gets hard and unresponsive and I need to use a lot of force to stop as I would expect, not sure if the brakes would still randomly fail without the booster connected.
I'm thinking I will go with an OEM master cylinder if I can get one online for a decent price (and it looks like I can) since that is a critical part and could cause a total loss of braking If it fails, but for the booster I am thinking I will go with a quality aftermarket unit since it's not as critical as I can still drive with no power brakes if I have to, but I obviously don't want to!