brake lines leak at fitting
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,526
Likes: 104
From: Stafford Va
brake lines leak at fitting
I have a brake line that leaks at the master cylinder. It is weeping from the nut/line. I have loosen it and retighted it, no luck any ideas? This is the second hard line and the only place it leaks. Thanks
Burning Brakes
Joined: Mar 2013
Posts: 1,018
Likes: 581
From: West Monroe Louisiana
2023 C3 of the Year Finalist - Unmodified
You might try backing off a little and then retightening several times.
I did this when replacing my whole brake lines and they would seat a
little more each time. If this doesn't work, the flare on the line might be bad.
Donnie
I did this when replacing my whole brake lines and they would seat a
little more each time. If this doesn't work, the flare on the line might be bad.
Donnie
Safety Car
Joined: May 2004
Posts: 4,351
Likes: 1,578
From: los altos hills california
The flared end of the tubing needs to sit as square to the fitting as possible. If it is slightly bent straighten it, then hold the tubing against the fitting until you feel it seat. Then while holding, tighten it. If that doesn't work, loosen and tighten it progressively a few times, each time a little more. Don't overdo it, start a bit lightly. You should be using a flare nut wrench.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
And you might check the flare for cracks- it's possible that it has a crack in the radius of the flare. Clean the tube really well, and a flashlight and a magnifying glass.
Team Owner
Joined: Sep 2006
Posts: 31,214
Likes: 4,302
From: Westminster Maryland
Hi V,
My comment/thought is a variation on the suggestions already given…
I found that the line needs to be 'tweaked' until it fits into the fitting or mst/cyl on it's own….with the flare nut pulled back.
It must be level and square to the fitting. You CAN"T rely on the flare nut to make any 'final corrections' as it's tightened.
In other words you can't use the flare to pull the line into position. The flare nut is there to make the 'seal' between the line and the fitting's 'seat' occur. It's not there to refine the 'fit' of the line to the fitting.
This seems to be most true on the shortest lines and those with a sharp bend just before they enter the fitting.
Regards,
Alan
My comment/thought is a variation on the suggestions already given…
I found that the line needs to be 'tweaked' until it fits into the fitting or mst/cyl on it's own….with the flare nut pulled back.
It must be level and square to the fitting. You CAN"T rely on the flare nut to make any 'final corrections' as it's tightened.
In other words you can't use the flare to pull the line into position. The flare nut is there to make the 'seal' between the line and the fitting's 'seat' occur. It's not there to refine the 'fit' of the line to the fitting.
This seems to be most true on the shortest lines and those with a sharp bend just before they enter the fitting.
Regards,
Alan
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Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,526
Likes: 104
From: Stafford Va
They are not SS just the steel lines from advance auto. I have just bent another one and put it on. Waiting to see if that fixes it. o leaks anywhere else.
Last edited by vstol; Apr 23, 2017 at 11:38 AM.
Drifting
Joined: Jun 2008
Posts: 1,565
Likes: 111
I had this trouble on my new SS hard line fittings as well. I just kept backing them off and re-tightening until they stopped weeping. It normally takes a little more torque on the fitting than I feel it should in order to get them to seal. But I agree, it's frustrating.
Race Director
Joined: Mar 2016
Posts: 14,332
Likes: 8,139
From: Napa Valley California
I've built my own hard lines for years. Loosen the nut and slide it back, take a piece of steel wool or scotch bright pad and clean the fitting mating surface and the inner/outer surfaces of the flare. Check for any twisting of the tube end or fractures and double check the alignment as mentioned above. Check the fitting for any scratches and replace it you find any. Also check to insure the flare end has equal thickness all around. If not cut the end and, replace the nut, sleeve and re-flare the tubing end. If the nut has been over-tightened, its toast. Cut it off and replace it. Good luck...
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,526
Likes: 104
From: Stafford Va
I give up!!!!! I benched bled the master cylinder before putting it on the car. I have no leaks I feel confident I bled it well. I used the Mity vac to bled the brakes but the air kept coming which I thought might be from around the hose. After I did that I put the speed bleeders back on and again bled the brakes. I went through a lot of fluid but I did it. The pedal is still soft and to add salt to the wound I started the car and put it in second gear then hit the brake pedal and nothing!! What the heck is going on??
Drifting
Joined: Jun 2008
Posts: 1,565
Likes: 111
I give up!!!!! I benched bled the master cylinder before putting it on the car. I have no leaks I feel confident I bled it well. I used the Mity vac to bled the brakes but the air kept coming which I thought might be from around the hose. After I did that I put the speed bleeders back on and again bled the brakes. I went through a lot of fluid but I did it. The pedal is still soft and to add salt to the wound I started the car and put it in second gear then hit the brake pedal and nothing!! What the heck is going on??
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,526
Likes: 104
From: Stafford Va
Thanks Neil I have C4 calibers and old school tomorrow. However the volume of fluid from the front is good using the speed bleeders but the rear is way less. Both are the same when I used the mity vac.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,526
Likes: 104
From: Stafford Va
Did old school bleeding last night for a while. The fronts have no air in at all and work well. The rear I just can not get rid of the air bubbles. If I have the car in second (on jacks) and mash the pedal to the floor it will stop it, not got if I was going 10 miles/hr. Still have the soft pedal
Melting Slicks
Joined: Sep 2006
Posts: 2,810
Likes: 469
From: Wichita Kansas
I quite honestly feel your pain, I went thru many of the things you are experiencing in the last couple of months and moved right to my wits end with it. My biggest problem turned out to be a faulty pass front caliper; once replaced (I failed with the rebuild), that problem was solved... The next was the hose on the driver's side front; could not get it to quit leaking at the caliper connection. A fellow forum member sent me an old style thick copper washer to try and that did the trick. During all of this, after bleeding several times the traditional way and with the stupid mighty vac, I finally got tired of having brake fluid on my hands and garage floor, I used the gravity bleed process on all for wheels, in proper order, and have great brakes now on my '72. With that method, patience is very very important. And tapping the calipers with a rubber hammer is also important. Patience and follow-thru. One step at a time. Good luck
Safety Car
Joined: May 2004
Posts: 4,351
Likes: 1,578
From: los altos hills california
Did old school bleeding last night for a while. The fronts have no air in at all and work well. The rear I just can not get rid of the air bubbles. If I have the car in second (on jacks) and mash the pedal to the floor it will stop it, not got if I was going 10 miles/hr. Still have the soft pedal