Brake Line Leak

[Zaggnutt]

I recently replaced the rear leaf springs on my sig truck. Because of my complete lack of experience doing this work I did not loosen the brake lines when I dropped the axle and the brake line at the brake hose junction on the axle sprung a leak. After over-tightening I stripped the threads in the brass block. (I also noticed the flares were completely flat and notched) I pulled a piece of brake line off an F250 because I didn't want to buy a flare kit, AA's were all rented, I was already at a U-Pull-It place gettin' other stuff. Tried putting RTV around the flare nut threads, plumbers tape, etc. Long story short, it didn't work. brake fluid softens everything. I was looking for an easy way out and it didn't work.

I bought a new brake hose and junction block, bought a Harbor Freight double flare and went to work.... Broke the HF kit on flare #2. Got an old school kit from my gf's dad and it worked great...... Except I still have a leak.

The leak is coming from inside the flare nut on the pass. side wheel at the cylinder. I put the old brake line and nuts back on, flared both driver sides, and both pass sides. only leak is from pass side. Last night I cut it and flared it for the 3rd time (maybe 4th) and it still leaks. tried filing it flat, sanding it more smooth with sand paper, enlarging the brake line hole on the inside to cup the cylinder better. I am out of ideas on this thing. Can anyone with experience give me some ideas here?

* I did notice there is a fine ring worn around the cylinder cup where the old line was probably overtightened by the PO.

 

[franklin2]

The problem with these flared fittings, you can re-flare the line, but if you damage the seat in the wheel cylinder, you are done. It may be hard to see, but there is a dome in the wheel cylinder that mates to the cone in the flare of the line. Sometimes there is something wrong with the line, or it has been overtightened at some time, and it will make a mark or dent in the cone in the wheel cylinder. Then a new line will not seal. You will probably have to get a new wheel cylinder.

I believe you made some of this harder than it had to be. You could have bought the new hose assembly, and a couple universal lines that are already flared and have the fittings on them. The universal lines usually end up being a little bit too long, but on the several I have done, a couple of zig zags of the line as it crossed the pumpkin always took care of the extra length. If you are bending them by hand, you need large radius bends anyway and that takes up some of the line.

If you wanted to try it, you could go to the store and get a universal line and see if it would stop the leak. But if it doesn't, the wheel cylinder will have to be replaced.

 

[OLDBULL8]

Tried putting RTV around the flare nut threads, plumbers tape, etc. Long story short, it didn't work. brake fluid softens everything. I was looking for an easy way out and it didn't work.

Kinda hard for RTV to seal 2000 PSI brake fluid. Never never use plumbers tape (Teflon) on fittings in a hydraulic circuit. If you need an explanation, just ask.

 

[icanfixall]

Its time for a new brake wheel cylinder and probably more new line. But try the wheel cylinder first. You may get lucky and it seals.

 

[yARIC008]

Kinda hard for RTV to seal 2000 PSI brake fluid. Never never use plumbers tape (Teflon) on fittings in a hydraulic circuit. If you need an explanation, just ask.

Question, how would you seal this then without tape? It doesn't have flare fittings.
http://www.speedwaymotors.com/Speedway-Drum-Brake-Residual-Valve-10-PSI-Purple,7502.html

 

[yARIC008]

I bought a new brake hose and junction block, bought a Harbor Freight double flare and went to work.... Broke the HF kit on flare #2. Got an old school kit from my gf's dad and it worked great...... Except I still have a leak.

You should just replace the wheel cylinder, what are they, $15 now? Also, it is very difficult I have found to make a nice double flare. Best way I have found is, cut the line with a tubing cutter, buy a reamer from amazon, ream the ******* out really well, then take a dremel tool and use the sanding wheel attachment and sand the end of the cut as straight and flat as possible and put a little chamfer on there too as the double flare tool kit directions say. Then use the double flare tool and it should be a nice flare. Before I did mine like that almost every single double flare I made leaked. Drove me nuts.

Also I found to get the double flare to seat really well, you tighten the nut up pretty tight, then loosen and do it again. That really seems to make them seat properly.

 

[Zaggnutt]

The problem with these flared fittings, you can re-flare the line, but if you damage the seat in the wheel cylinder, you are done. It may be hard to see, but there is a dome in the wheel cylinder that mates to the cone in the flare of the line. Sometimes there is something wrong with the line, or it has been overtightened at some time, and it will make a mark or dent in the cone in the wheel cylinder. Then a new line will not seal. You will probably have to get a new wheel cylinder.

I believe you made some of this harder than it had to be. You could have bought the new hose assembly, and a couple universal lines that are already flared and have the fittings on them. The universal lines usually end up being a little bit too long, but on the several I have done, a couple of zig zags of the line as it crossed the pumpkin always took care of the extra length. If you are bending them by hand, you need large radius bends anyway and that takes up some of the line.

If you wanted to try it, you could go to the store and get a universal line and see if it would stop the leak. But if it doesn't, the wheel cylinder will have to be replaced.

Yeah, that is what I was trying to explain in my original post. I noticed a groove worn into the wheel cylinder cup. I bought a pack of flare nuts (I read that they can sometimes indent to the shape of the flare) and a wheel cylinder. I will post the results.

 

[Zaggnutt]

Thanks guys for all the responses and advice!!! I will post results after the wheel cylinder replacement - seems most likely the cause.

 

[OLDBULL8]

Question, how would you seal this then without tape? It doesn't have flare fittings.
http://www.speedwaymotors.com/Speedway-Drum-Brake-Residual-Valve-10-PSI-Purple,7502.html

If I've said it once, I've said it a hundred times.

TEFLON TAPE IS NOT A SEALANT, IT'S A LUBRICANT FOR THREADS.

 

[Zaggnutt]

If I've said it once, I've said it a hundred times.

TEFLON TAPE IS NOT A SEALANT, IT'S A LUBRICANT FOR THREADS.

Huh. Okay, then. Welp, I'm glad you said it 100 times cause I didn't know that.

 

[Zaggnutt]

Okay, so I was hoping to post pics of the damaged wheel cylinder, but it got blurry when I got close with the camera. I was hoping to show a pic of the ring worn into the brass cylinder cup - Oh well, you get the idea.

New Cylinder was Tuf Torque, Part# W37262 from Advance Auto. Cost was $17.99. Bled it, but haven't run it yet. Still holding pressure. It was extremely easy to replace... So easy in fact that I was certain something catastrophic would have to happen to offset it. It was unlike any experience I've had thus far working on this truck - It was that easy.

The only notes I have for anyone doing this job are:
1. New cylinder takes a 7/16" flare nut thread / 3/16" brake line opening. Original was 3/16" thread / 3/16" line opening. So I had to buy a new nut and flare the line one more time.
2. As we all know, some tools you can buy at Harbor Freight and some you cannot... I would put a double flare kit in the DO NOT BUY AT HB category. The one I borrowed was made in the USA (Hell yeah) by Imperial - Age unknown.
3. Something OLDBULL is always mentioning regarding truck work - KEEP IT CLEAN.
4. The best flares come from the best prep work. File your tip flat, sand it smooth if necessary, be patient and careful.

And as always - Thank you for all your help!!! You guys are always there to help and I appreciate it!

 

[Zaggnutt]

ON TO THE NEXT PROJECT!!!

 

[yARIC008]

If I've said it once, I've said it a hundred times.

TEFLON TAPE IS NOT A SEALANT, IT'S A LUBRICANT FOR THREADS.

OOOKAY, guess you should just put that in your signature along with all the other stuff you always say,

Question remains, how do you seal that fitting? You said to not use tape on a hydraulic fitting... I'm willing to bet if you don't use tape it'll leak.

BTW, glad the new wheel cylinder worked out for ya. They are pretty easy to change out.

 

[franklin2]

Question remains, how do you seal that fitting? You said to not use tape on a hydraulic fitting... I'm willing to bet if you don't use tape it'll leak.

I looked at that link. If you read the description you will see it has 1/8" NPT. That means it has pipe threads which are tapered. The threads do the sealing, so yes this particular fitting does need sealer. I would not use teflon tape on this particular application and if you did, very sparingly and keep it back from the end of the fitting. It's very easy for the teflon tape to tear off when it's assembled and clog things up. In most applications this is not a problem but I would worry about it with brake lines and fuel lines.

The other regular brake fittings like the original poster was dealing with do not seal on the threads. The threads are normal straight threads, if you find the correct nut, a regular nut that fits on a bolt will thread right on. The threads on these fittings are there just to press the seats together, they do the sealing.

The same with o-ring fittings like on the steering box. The nut is a straight thread and does not do any sealing. It just holds the line in place, the o-ring does the sealing.

So anything with national pipe threads would need something on the threads to boost the seal. Old Bull is correct in theory, pipe dope, teflon tape, and all the other sealers lubricate the threads so you can tighten the fittings tighter, making a better seal. But then comes along a person who has a damaged pipe thread, puts a whole *** of teflon tape on it, and it seals. Even though theoretically the tape is there just to lubricate the threads, under low pressure conditions it will help seal it also, I think any plumber will tell you a heavy wrap of tape will get you out of a bad situation sometimes, even though it's not the "right" way to do it.

 

[Wyreth]

OOOKAY, guess you should just put that in your signature along with all the other stuff you always say,

Question remains, how do you seal that fitting? You said to not use tape on a hydraulic fitting... I'm willing to bet if you don't use tape it'll leak.

BTW, glad the new wheel cylinder worked out for ya. They are pretty easy to change out.

This is what you use: http://www.rectorseal.com/index.php/rectorseal-no-7/

Or another manufacturers equivalent. Tape is a very poor thread sealant. PERIOD. Also, using it gives you the fun ability to add debris/clogs/restrictions into your system.