Master cylinder leakage

[Billib54]

At wits end. Have installed third MC on 62 lancer, manual brakes. All have leaked from spare port on bottom of MC. Tried various sealants and contacted manufacturer to no avail. Any ideas?

 

[jazak5]

same problem installed one of these

seems to work so far// some were installed on max wedge cars// I believe //but my exhaust manifold is right under my MC // my infrared thermometer showed a significant temp reduction///cooking your seals most likely with radiant heat off of the exhaust manifolds

 

[Billib54]

same problem installed one of these View attachment 1715791775 seems to works so far some were installed on max wedge cars// I believe //but my exhaust manifold is right under my MC // my infrared thermometer showed a significant temp reduction///cooking your seals most likely

Don't think that's it. Last one bench bled, left pressurized for 18 hours with tie raps, no leaks, installed on car. Leaks at spare port. 1/4 pipe plug. No leak at brake line. Perplexed.

 

[jazak5]

Don't think that's it. Last one bench bled, left pressurized for 18 hours with tie raps, no leaks, installed on car. Leaks at spare port. 1/4 pipe plug. No leak at brake line. Perplexed.

not an expert / but/ a 1/4 pipe plug (npt) is different than a brake line fitting....

a npt is a tapered design and a brake fitting is straight and designed to shoulder the flare of the brake line to support it against the flare inside the MC for the high pressure

Ive crimped and soldered a brake line fitting to block off a port on derby cars (only front brakes work so you can dig in while in reverse) poor mans line lock

 

[Billib54]

That it true. It came with a pipe plug in the unused port and is leaking around the threads.

 

[jazak5]

That it true. It came with a pipe plug in the unused port and is leaking around the threads.

unused port ? do you have the right MC ?

that year I believe was a single reservoir unless you changed it to dual ??

 

[Professor Fate]

That port is for a brake pressure warning switch. It gets plugged if car is not equipped with a warning light.
I've been really frustrated with the quality of pipe threads in many parts of late. Threads not cut cleanly, not deep enough (which translates to width also with a tapered pipe thread), etc. I would try cleaning the port really well, and using a different brass plug (not iron) in the port, with a dab of copper sealant.

 

[Billib54]

That port is for a brake pressure warning switch. It gets plugged if car is not equipped with a warning light.
I've been really frustrated with the quality of pipe threads in many parts of late. Threads not cut cleanly, not deep enough (which translates to width also with a tapered pipe thread), etc. I would try cleaning the port really well, and using a different brass plug (not iron) in the port, with a dab of copper sealant.

 

[Billib54]

Yep, single reservoir, just like pic above. Have tried several sealants and different plugs too. Have not tried copper sealant though. Going to try the permatex hydraulic (purple) sealant and activator this weekend after i clean it good.

 

[Billib54]

Thanks for the comments!

 

[jdsduster]

That port is for a brake pressure warning switch. It gets plugged if car is not equipped with a warning light.
I've been really frustrated with the quality of pipe threads in many parts of late. Threads not cut cleanly, not deep enough (which translates to width also with a tapered pipe thread), etc. I would try cleaning the port really well, and using a different brass plug (not iron) in the port, with a dab of copper sealant.

china crap.big box stores are full of it