brake fluid leak, washer for brake switch at MC Options

[hndyhrr]

Discovered a fluid leak at the brake switch in the Master Cylinder (19mm).

Two questions,

What kind of washer is between switch and MC? Metal/fiber?

If I take the switch out will I loose the brake fluid?


Thanks

Renee

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[Superhawk996]

If you are getting fluid into the switch the m/c and it’s seals are shot.

[hndyhrr]

If you are getting fluid into the switch the m/c and it’s seals are shot.

It's leaking from around the threads of switch as far as I can tell right now. Also if MC is failing would it make any noise like a whirling/whining noise? Last time I drove her at the end of about 20 mile twisty drive I could hear that kind of noise. could feel vibration when hand on top of gas tank.(fuel pump under tank). Still had full hard breaking also at end of drive (thank god) I think I have two problems. brake leak and possible fuel pump. Just shoot me now!
Really feel like I am done.!!!!!

[Superhawk996]

Master cylinder failing doesn’t make a noise - the seals within just start leaking internally and bypassing pressure

If the fluid is on the switch - make sure it isn’t just leaking from the supply line grommets at the top of the m/c and dripping down onto the switch. There was also a bad batch of 914Rubber master cylinders that were prone to leaking at the Welch plug up top and that conceivably could leak down onto the switch too.

The switch itself and its plunger / actuator is in a dry section of the master cylinder between the seals. You can remove the switch without losing brake fluid. However, if you find fluid inside, it’s a sure sign the seals on the pressure differential piston(s) have gone bad.

Here’s what the internals are:

Arrows pointing to the differential pressure piston seals

[hndyhrr]

Master cylinder failing doesn’t make a noise - the seals within just start leaking internally and bypassing pressure

If the fluid is on the switch - make sure it isn’t just leaking from the supply line grommets at the top of the m/c and dripping down onto the switch. There was also a bad batch of 914Rubber master cylinders that were prone to leaking at the Welch plug up top and that conceivably could leak down onto the switch too.

The switch itself and its plunger / actuator is in a dry section of the master cylinder between the seals. You can remove the switch without losing brake fluid. However, if you find fluid inside, it’s a sure sign the seals on the pressure differential piston(s) have gone bad.

Here’s what the internals are:

Arrows pointing to the differential pressure piston seals

Thanks for reply

I've attached pic, it's leaking where the blue line is. Felt the top of MC and it is dry as a bone.

[dtmehall]

I would add, that if you're investigating this area of the MC, and you suspect that there is a leak, you'd probably be better off replacing the MC

[bkrantz]

I suggest loosening the switch. If fluid drains out, the MC has failed. There should not be any fluid inside the switch cavity.

[hndyhrr]

Thanks for the help and suggestions. I will loosen the switch in the morning and let you know.


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My lucky day probably the fuel pump is going out also as it is making a whiney/whirlying sound.

Just poke me with a fork. I am done. lol

[fiacra]

There was also a bad batch of 914Rubber master cylinders that were prone to leaking at the Welch plug up top and that conceivably could leak down onto the switch too.

Now that brings back painful memories! I had the good luck to get one of those. Do yourself a favor and pay the extra few $$ to get the Ate MC. It's worth it. Unfortunately replacing the MC can be one of the most miserable jobs to do on these cars, and I had the joy of doing it twice because of that. If you are doing it yourself my strong advice is to put the metal lines and grommets in off the car, and then install the new MC. Put new vinyl lines and blue brake hose on first as well. You'll need to move the gas tank to do it that way, but it is much easier. Don't forget the grommet where the lines go through the sheet metal in the body, and new washers for the banjo bolt. If you have to replace the fuel pump, take this as your opportunity to replace the fuel lines under the tank as well as the sock and the fuel filter. I drained the tank with a inexpensive battery powered fluid transfer pump. I think HF has one for ~$10. This job is the classic example of "scope creep" where it seems like you only have one thing to do, but then you realize it just makes sense to do a whole bunch of other things at the same time. So yeah, it may seem like a "stick a fork in me" moment, but it is all doable and when you're done with all of that you then get to have the joy of bleeding the brakes and you quickly realize it is really a carving fork you've had stuck in you (IMG:style_emoticons/default/evilgrin.gif)

BTW, make sure your fuel pump isn't just straining against a clogged filter or a kinked line.