Brake problem

[bdepedro]

Late this past winter my brakes got very spongy and the next day I had almost no pressure at all. I noticed some brake fluid leaking out where the pedel shaft goes into the master cyl so I didn't drive the car for a few weeks while I ordered a power booster/master cyl upgrade.

Before I could put the parts on I had to move the car out of the garage and the brakes felt fine. I've been driving the car since then without issue but this past weekend toward the end of a long drive on a fairly hot day the brakes got spongy again. By the time I got home the air temp had dropped and the brakes came back somewhat.

At the very least I'm going to bleed the brakes. I may wait on the master cyl change till I do some other work.

3 questions:

If there is air in the lines could engine bay heat in combination with outside heat cause the brake fluid to thin and leak?

Has anyone installed a heat shield between the master cyl and headers?

Long time since I've bled brakes. Is there a better way then the old school one guy pumps brakes while one opens lines?

Thanks!

 

[TOM B]

If you dont have the correct tools or can't afford them then the old two guy method works great. If you brakes get spongy only when the heat is up then the seals on the master cylinder are going bad and fluid is starting to by-pass the seals internally. I use a synthetic brake fluid, last longer and dont rust out the wheel cylinders

 

[Ogre]

I would go ahead and change the master cylinder before you regret not doing it and have to replace front end parts. As far as bleeding the brakes, go to a local auto parts store and buy 4 new brake bleeder screws with the check ball/valve. Then you just open them up one at a time (start with the one furthest from the master cylinder and work your way to the closest) with a piece of vacuum hose connected to it and run into a container. One person brake bleeding doesn't get any simpler than that.

 

[bdepedro]

Thanks for the replies, I'll go ahead and replace the master cyl with the conversion booster I have and also replace the bleed valves with the check valves. Seems that that way you can either do it the old way it you have a helper or do it solo if you don't.

I've also thought that synthetics would be a good idea for the brake system. What brand are you using?

 

[Ogre]

Name brand don't matter, just make sure it is DOT 4 and bleed it through the whole system. Don't use the DOT 5 if you find it. Makes brake pedal too hard.

 

[bdepedro]

Name brand don't matter, just make sure it is DOT 4 and bleed it through the whole system. Don't use the DOT 5 if you find it. Makes brake pedal too hard.

My new master cyl specs DOT 3, which I've been using already. What is the difference or advantage to using DOT 4?

 

[Ogre]

Too much info to write about the difference between DOT 3, 4, and 5 brake fluid. Do a google search and decide for yourself. I went with DOT 4.