'79 Brake pressure failure switch leaking

Last Friday completed the draining and bleeding brake lines with DOT3 in my new '79. Next morning, I noticed reservoir level was down and then found a leakage from Brake pressure failure switch under the MC. Looks like it is wiring is the body, where it touches.
Qns:
[list]
[*] Do I need to replace the O ring in the shuttle valve? How ease is it?
[*] Should I remove the switch and bolt it (no brake failure warning) to close the leak?
[*] Do I need to replace the switch from ronfrancis?
[*] Any other idea?
[/list]

Apologies for many questions..

Vijay, for now you can put a short bolt with a copper washer under it in the hole to stop the leaking.

Replacing the O-rings is very simple. It could be done with the valve in the car if you don't want to take the brake lines loose.

What does the switch look like? All crusty and rotten?

I changed my MC Sat. and that switch broke taking it out of old MC. Just had to put a 3/8" fine thread X 1/2" long bolt. I used a nylon washer instead of copper. Copper washer cost more than a $1 and nylon cost $.35. Tightened the bolt down in new MC and everything is fine. All that switch does is warns if you are low on brake fluid, I look under hood every time I drive my B, so I don't need that switch on mine.

A nylon washer would work, too. The switch lets you know that one side of your brake system has failed, either the front or rear. It won't let you know when you are low on fluid. Hitting the car in front lets you find that out.

Just put a new master in mine - no leaks with the switch out. Not sure your seals are o.k. I think a leak here means you have other problems with the m/c seals, but others with more expertise will hopefully chime in.

Coincidentally, I needed just the boot for the outside of the master cylinder - where it goes into the server. And I now have a brand new rebuild kit for a 75 to 80 m/c that I just bought from Gordon at the B-Hive for $22.36, minus the one external boot, that I don't need. All the seals are there for a rebuild. $5 plus $4.95 for U.S. Postal flat rate and it is yours.

Be sure you need it though. I think a leak like the one you're describing means you do. I also have the original Lockheed master brake and clutch cylinders that I would part with for $25 each plus shipping. Both work fine - I replaced all the hydraulics on the car.

Vijay is talking about the brake fail switch that is located on the inner fender on an early car. Got nothing to do with the MC. His seems to be leaking past the white switch which turns on the dash warning light, a common symptom when the o-rings on the shuttle piston get hardened.

Wray - he said "Last Friday completed the draining and bleeding brake lines with DOT3 in my new '79. Next morning, I noticed reservoir level was down and then found a leakage from Brake pressure failure switch under the MC".

You sure? (:P)

Typos can change the whole meaning of a post. Sounded to me like he bought a new 79.......

Does anyone have any pictures of the switch and O-Ring?

Thanks Wray, Gary..
Here is a pic of Pressure failure switch. I don't think it needs a replacement. Please advice..

I wud like to change the O-ring. Can u lemme know which one is it? Is it the one visible in the picture or inside the MC?
Can I remove the entire switch by loosening the white-plastic nut witha spanner?

One more Pic

Vijay, I just swapped that switch over from my old BMC to a new one. I did not see an o-ring so that is why I was asking for pictures. I wonder if it could still be stuck to my old BMC...

Yes, I just used a wrench to R&I the switch.

Jeff,
CanI remove the switch w/o draining the fluid? it doesn't gush out?

That sure looks like my 1980, and there is no o-ring around the switch - is it supposed to leak there? I don't think so. Neither of the m/cs I have looked at in the last week - the Lockheed I removed that still works and the Uroparts I just installed - had fluid around the switch.

I had the switch completely out of my new recently bench bled and installed m/c - not even a drip. If that is a '79 and not a '69, I think you may have a bigger issue here. Like bad seals in the m/c.

Vijay - what year is your car?

Because of this thread, I just tossed a rubber O-Ring around my sensor before reinstalling it...

Can anyone confirm if there should be an O-Ring or washer of some kind or not??

It does not appear to be leaking yet, so I may be okay. It was a really thin washer so it does not poke out.

As far as a copper crush washer goes, this sensor is plastic so I don't think it could crush anything even if it wanted to.

@Dave, This is a 1979 MGB. You are correct that it shudn't be leaking from the switch. In cud very well be leaking from the seals (#19 of MC components in Haynes/Robert Bentley's Manuals) . For now, I've removed the switch and sealed it with a Nylon washer-3/8 X 1/2 inch fine thread. Not sure what the impact is. Any expert opinion? I did take for a test drive so far so good. Will consider rebuilding MC at a later date.

@ Jeff - There is no O ring/washer near the Pressure failure switch - Plastic switch just screws in to the MC. There should NOT be any oil coming in to this area of MC. If there is oil seeping in to this area of MC, it is a malfunction and will definitely leak out from Switch through Sensor.

@Wray - Any suggestion?