Brake Trouble Switch Leak!
 

So,

I was rebuilding my brake system on the 74' 911 after its 20 year dormancy by rebuilding and replacing all the rubber parts. I rebuilt the master cylinder, calipers and put new rubber lines all round. I was in the process of bleeding the brakes and noticed that the trouble light switch on the master cylinder was leaking through the stem of the switch plunger. So I bought a new one all fresh and new from ATE, and it leaks too!!!:mad:

So, now I ask, did I get a bum switch or are the seals around the brass pistion in the master cylinder that triggers the switch the problem? They were the only seals that were not part of the rebuild kit. Are these seals available?

Appriciate your help.

CR@P!

I found out that one of the seals on the piston that the trouble light switch rides on is broken. Unfortunately, those seals do not come with the rebuild kit much less have a part number. So, after a $70 rebuild kit and a $30 pressure switch. It looks like I'm staring at a new $170 master cylinder for a $1 seal. Ahh the joys.

Does anyone have a source for these seals?

I will check on the classified adds, but does anyone have a trashed 19mm master cylinder that I could salvage this trouble light piston from?

Try using teflon tape.

<b>Forget the Teflon tape, or more torque, either! That switch doesn't mount to a 'wet'` area of the master cylinder!!!</b>

If there is a leak ... it is from the O-rings on one olr both of the two plungers that operate the switch! Take out the hex plug and replace the O-rings.

Thanks Warren,

That is my problem. One of the seals on the plunger is shot but it is not a simple o-ring, it is a cup type seal like the main master cylinder seals. And the seal does not have a part number according to our host along with other Porsche parts houses. So there is no way to order one.

Blume Dispare and Agony on me...

These guys bill themselves as "automotive hydraulic specialists." Maybe they have a seal that will work. It's worth a call.