lvrpool32

My brakes are really beginning to get to me :mad

I recently finished putting everything for my brakes back together ,which included a new master cylinder and new lines from the master cylinder to the brass distribution block. Car is a 69 with power brakes.
Unfortunately where the lines go into the block, wont stop leaking!!
They unions are tight, but I bleed the brakes and an hour later fluid is leaking past the threads.
I am using a valvoline "synthetic blend", someone told me last night that that could be the issue, that synthetic based brake fluid is much thinner and will find leaks. Is this so?
Also can you put joint tape around these fittings? I was always told not to do that on pressure systems....
Anyone got any ideas....can't drive my car without brakes :sad:

thanx
Nick

GaryS

I don't think this is an issue with synthetic versus dino-based oil. Most of that discussion is old wives tales. Have you chased the threads of the MC and the brake lines? I would use a good tap and die and clean both sets of threads. Then, I would use some teflon tape to seal the threads up. You are not supposed to use tape on those fittings that require a good ground, such as temp sending units that screw into the block.
Gary

1979toy

Clean both sides of your flare fittings very carefully and reassemble.

MikeC

:withstupid:

And hopefully you haven't damaged the flare

vettery

Quote: "I would use a good tap and die and clean both sets of threads. Then, I would use some teflon tape to seal the threads up. You are not supposed to use tape on those fittings that require a good ground, such as temp sending units that screw into the block."

Not designed to seal on the threads. Look for damage on the tube seat or the tubing flare. Tube seat can be replaced. You may can get the right size from someone that remanufactures mastercylinders.

BB68Vett

I have a similar problem on my distribution block and I have identified the issue. One the flares on the distribution block is cut too shallow. The side that is cut about two to three threads deeper has no problem sealing while the shallow flare leaks. I will try some permatex non-hardening on the threads. I use Dot 5 silicone brake fluid. Otherwise I may have to buy another distribution block but at $100 I am not rushing to do so. You may want to check the depth of the flares in the distribution block and compare to your original I am assuming you replaced your distribution block).