Technical Why does almost every fitting on my brake system leak?!

Today could have been awesome...instead it was exactly what I was hoping wouldn't happen.

I ran all new lines for my AV8 build using that copper colored stuff. Used factory flares wherever I could, and when I couldn't, I used my buddy's really nice snap-on double flaring tool.

Thank god I started with silicon DOT5 otherwise my car wouldn't have any paint left.

So what should I be looking at here? Did I maybe crank down on the brake line too much? Maybe I went too far on my flares? Any help would be awesome since this is the first brake system I've done in over 5 years.

Thanks guys!

 

Pics? The factory flares leak too?

 

They are guaranteed to leak if they are not double flared. HRP

 

They are double flared. I can't remember which ones are factory and which aren't but I have maybe 5 that done leak lol.

Here are some pics.

 

By factory flares I assume you mean store bought lines that where pre flared? And by copper colored you mean the nickel plated line that Napa sells? Check and make sure the flares seal against the nut and that the inner double flare was not cracked. I have been making up brake line and fuel lines for over 45 years with no issues but I have to admit that I have had some problems from time to time the last 5 years, and I have professional flaring equipment including a $500.00 hydrolic unit. I do not think the line material is what it use to be quality wise. Take your time ,double check each stage of the flaring process and do not over tighten them or they will crack. Larry

 

Might be a dumb question but you are using brass connectors that take a flared fitting right?

 

How about a pic of inside the union? I am wondering if the union is for double flare or possibly bubble flare?

 

All brass fittings are not made for flares. HRP

 

There are discussions on here that talk about the silicone fluid leaking where the old stuff didn't.
Perhaps a search may help?

 

I think you need 5.1 synthetic.

 

I will look into that. But let's be honest, if it's leaking with this stuff I find it hard to believe that using different fluid will make all the difference

 

I tighten brake lines about as tight as I can get them, it often fixes the leaks. But not always.

But I also haven't messed with silicone fluid for decades.

 

Agreed. Is there a cone inside the union to match the flare? Flares look good. No reason they should leak.

 

Google discussions on silicone, that is normal from what I've read.

 

Note the difference between tube nut ends, inverted double flare (Recess) as opposed to metric bubble flare (Flat)

 

On the last flare, the double flare, don't tighten it down so tight in the jig, let the fitting crush it a little more when tightening . I always use a steel union clamped in a vice just to seat it lightly in before install on vehicle...................

 

That could have been where I went wrong. I'm pretty sure I have those double flares hell when I had them in the flaring tool

 

Teflon tape on Inverted flare fittings?

 

i have always made my own brake lines without a problem [other than forgetting to put a nut on the tube first] but recently i made three flares on a truck i was working on and ALL three leaked. what i found was the "cone" on the flaring tool had stuck/froze crooked on the tool so it was making the flare lop sided. just enough that it was hard to see. i used a little oil on the tool to get it to move freely and it solved the problem

 

Never! seal is at the flare not the fitting threads

 

exactly

 

Such a bummer. But thank you all for the help! I'll be pulling everything off tomorrow and taking a look.

 

Loctite makes a hydraulic thread locker that is available thru Fastenal. I have used it with some luck. I even put a small amount on the flair itself.

 

Break them loose and re-tighten them. Sometimes it takes a few times but usually works for me.

 

You need to really get some torque on those hose ends. Sometimes "tight enough" leaks.


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I agree with loosen slightly and re tighten. I have not seen the black brass fittings, looks good.

 

^this, try loosening and retightening the connections, some one also mentioned not over tightening the second flare so it can conform to the fitting, also good advice

Oh and never use Teflon tape or hydraulic sealant....has no place on flare fittings


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I was taught a trick by an old timer at a brake and suspension shop I used to work at. The trick is to loosen and tighten the fitting a bunch. 20-50 times even. Gradually tightening as you go. It gets them to seat. I've even had to do it to the "factory" fittings on the sticks you buy at the auto parts store. They will stop leaking if you do this.

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Look at the union 2 out of the last 3 I bought were junk. They were machined so the threads bottomed out before the flare met the cone.