Brake Light Switch

[RalphG]

I suspect there is no easy fix for this one but does anybody know if the brake light switch on the end of the master cylinder is repairable? Mine on the 52 Merc will not work. Power on one wire going in but nothing coming out the other terminal when the brake is applied.

[Ken/Alabama]

No , get a new one. They're not very expensive.

[alanwoodieman]

are you using DOT 5 brake fluid? if so you need one from a Harley Davidson mc shop or one from ron francis wiring. dot 5 tends to leak into the back part of the switch and then they don't work

[RalphG]

Originally Posted by alanwoodieman

are you using DOT 5 brake fluid? if so you need one from a Harley Davidson mc shop or one from ron francis wiring. dot 5 tends to leak into the back part of the switch and then they don't work

No, this has dot3 fluid. I suspect that 40 years of inactivity has something to do with the switch not working.

[Drbrown]

DOT 3 and 4 tend to absorb moisture and thus lead to internal corrosion. As Ken suggests, get a new one, properly flush the system and replace with DOT 4. You can convert to DOT 5 but that involves more complete flushing work. I recommend you search the threads about the issue.

[flat 39]

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Don't get a cheap $5 switch. They only last about a month. get either a motorcraft or H-D switch.

[TJ]

Those switches are very generic. You can get one from most auto parts stores. Usually about $5-7.

[RalphG]

Napa has supplied all my brake parts so far. Guess I can try them for this too.

[Mr. Will]

Originally Posted by RalphG

Napa has supplied all my brake parts so far. Guess I can try them for this too.

I just bought a pressure switch from NAPA for my 36 total was around 11.00. I used a switch for a jeep that uses the spade connection rather then the bullet as I am not moving the battery box and this gives me clearance. Same switch from Macs is 32-38 with plug, I had the plug.

[tubman]

If you're going to flush your brake system (this seems to be an appropriate time), do yourself a favor and install a set of "Speed-Bleeders". They make bleeding brakes an easy, one-person task.

[RalphG]

Originally Posted by tubman

If you're going to flush your brake system (this seems to be an appropriate time), do yourself a favor and install a set of "Speed-Bleeders". They make bleeding brakes an easy, one-person task.

No, I won't be doing any brake fluid flushing. I replaced all the cylinders and some of the lines earlier this year. All new dot3 fluid so it has had it's flushing. Dot3 is all I have ever used in every vehicle I run. Would there be any benefit to changing over to dot5 fluid? Other than the water resistant properties of dot5?
I'd never heard of the speed bleeders but read a little about them at this site
https://jimsgarage.wordpress.com/200...t-4-and-dot-5/

[Ray Balukas]

MR Will do you have the Napa part #. Thanks Ray

[Mr. Will]

Originally Posted by Ray Balukas

MR Will do you have the Napa part #. Thanks Ray

Ray,
NAPA # is SL139

[RalphG]

Originally Posted by Mr. Will

Ray,
NAPA # is SL139

Thanks for that part number Mr. Will. It should help me get the right part first time.

[Ray Balukas]

Thanks also Mr Will.

[Frank Miller]

Believe it or not I had a harley one fail with DOT 5. Replaced with another one and it has been good for a number of years now.

[rotorwrench]

DOT 3 is a fluid that should be flushed out at periodic intervals but if you are OK with it then continue to use it. DOT 5 has its own idiosyncrasies so it's apples & oranges to me.

[RalphG]

The original style brake light switch for the 52 Mercury is listed at Napa as part number
MPE SL134SB
It has the original style push on bullet connectors like mine.
https://www.napaonline.com/napa/en/p...4SB_0223399595

[weemark]

Just go in and ask for a hydraulic brake switch which has push on terminals on it, lots and lots of cars use them - any good parts house should know what you want without a part no.

[1942deluxe]

Ford p/n C1AZ 13480 A. Still a good number.