Habeed

On hot days, I noticed that my brake pedal would intermittently sink quite a bit more than usual before engaging. I took my 1996 Accord to the mechanic, and he wouldn't take my money. He said that since he couldn't reproduce the problem (it was a cold morning) he wasn't willing to 'condemn a part'. Called up Just Brakes, they wanted $275 for a new master cylinder.

So I went to Autozone, spent a grand total of $58 and got myself a new Fenco master cylinder. Took me 4 hours, but I eventually got it in the car and all of the wheels bled. (I didn't have a jack, and I didn't have a very good brake bleeding kit, so it was a real PITA. Must have spilled a quart of brake fluid on the garage floor)

Drive test : works great. Exact same pedal feel as the previous master cylinder, except hopefully this intermittent problem with the pedal sinking has been fixed. I'm assuming that the original Nissin master from 1996 has gradually lost its O-rings from exposure to brake fluid.

My concerns : is there any other cause that could create the symptoms I experienced, where the brakes work fine normally but the pedal intermittently sinks an extra couple inches on hot days?

Second, I feel real bad about only putting a $40 critical part in the brake system. Should I worry about it, or just leave it alone? After all, the OEM part costs $150 and seems to commonly fail on people in a pretty consistent manner. I didn't take it apart, but the Fenco part looked ok.

And finally, does it help to bleed the brakes perfectly using a vacuum pump, or is it good enough if you just get most of the air out? I thought about it and realized that if I really wanted optimal braking performance I'd need to convert the car to ABS with disc brakes on all 4 wheels. No, I don't race, I just want to drive a safe car.

Edit : I think I'll leave it alone, and if I have problems again, I'll buy the OEM part and get a vacuum pump.