[Mgs] Mgs Digest, Vol 89, Issue 8

[Glenn Schnittke]

Inside the body of the five-way union that the switch threads into is a 
double ended piston. It is shaped like an hourglassand has an o-ring 
seal at either end. Each end of the body feeds either the front or the 
rear brakes. If there is a pressure failure in either the front or rear, 
that piston is going to move one way or the otherand set off the switch. 
If everything is working fine there will be equal pressure on both ends 
of the piston. If you have fluid at the center of the switch, the first 
step is to replace the o-rings, but check the walls of the body. The 
piston itself can wear, but the body walls should be as smooth as the 
walls of the master cylinder andthe slaves. The o-rings arenot special 
and you should be able to replace them from your local hardware storeif 
not an auto parts shop. Think plumbing and water valves. Your worst case 
scenario is replacing the union body.

You didn't mention what year car you have. I assume from your 
description that it's a late chrome bumper car.



On 10/10/2014 1:00 PM, mgs-request at autox.team.net wrote:
> Message: 3
> Date: Fri, 10 Oct 2014 10:01:22 -0700
> From:"sdesalvo at frontiernet.net"  <sdesalvo at frontiernet.net>
> To: mg list<mgs at autox.team.net>
> Subject: [Mgs] brake pressure failure switch '72 MGB
> Message-ID:
> 	<1412960482.11829.YahooMailNeo at web161803.mail.bf1.yahoo.com>
> Content-Type: text/plain; charset="us-ascii"
>
> I cannot stop brake fluid (silicone) from leaking out the top of the pressure failure switch. The fluid leaks into the cavity where the electrical pigtail connects to the wiring harness. I replaced the switch and it still leaks. Any help would be appreciated.
> Thanks in advance,
> Sam