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FrozenNorthman 11-30-2012 07:57 PM

Thread sealer on brake lines?
Hey guys, this is my first time posting, this is quite the site you have here! I just replaced the brakes lines from the booster(is that right booster? not the master cylinder, but the secondary unit mounted on the drivers side, right near the firewall) to the calipers, including a new flex hose. when I pump the brakes, all I get is a gurgling sound, and fluid leaking from where the line meets the flex hose. my question is, should I be sealing this somehow, or will the fluid just eat the sealant? are there any other possible causes Ive overlooked?

elsolo 11-30-2012 10:15 PM

There is no place on a brake system where it is appropriate to use any kind of sealer.

I couldn't make sense of your post, but:

Brake boosters have no hydraulic lines, just a vacuum hose. The booster is mounted between the firewall and the master cylinder.

ABS units have hydraulic brake lines coming in/out of them.

mikebontoft 12-01-2012 12:01 AM

wait so did you replace the thing on top of the big black round thing or the plastic container right next to the fuse box?

macdiesel 12-01-2012 07:18 AM

no sealant. either something isnt tightened all the way or its broken. Post up a pic, night be helpful.

sailor 12-01-2012 01:36 PM

Major leakage when installing new brake lines is unfortunately all too common.

The seal comes from the metal of the brake line being "crushed" into the receptacle it attaches to, and it's critical that these pieces match & line up properly before final tightening.

The first common issue come from a mis-match of components. there are TWO types of flares for the end of the brake line in common use, and they do NOT interchange. The receptacle at the end of the flex line HAS to match the type of flare at the end of the steel line for it to seal.

If you look inside the union at the end of the flex line and see a "cone" shaped center, your steel line needs a recessed flare to match. If the flex union has a recessed center, your steel line needs a "ball" flare that protrudes to mate with it.

The second issue can come from trying to "force" the fittings together. When the steel line is bent to fit, it needs a straight end section that fits fully into the union B4 screwing in the compression nut. If this area is bent or angled into the fitting it can be pressed in off center by the nut and will NOT seat properly, leading to a leak that further tightening will not fix.

Making this situation even MORE fun, is the fact that sometimes a steel line will need different flares/nuts on each end to match the unions it attaches to. MOST generic steel lines have the same fittings on each end, so it's easy to end up with the wrong "match" at one of the ends if you don't know about this common pitfall.

Take another look, and see if one of these scenarios matches your problem.


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