Brake fluid leaks

[don t. - 72gmc]

70 GMC C2500 drums on all 4

All new parts/pre bent lines/etc with the exception of the distribution block, any in line tees. These were inspected, cleaned, blown thru w/compressed air.

Bench bled master w/o issue.

Started to gravity bleed hard lines.

I have a small drip, 1 every 10 or so minutes at the master front connection. Yes, I have flare wrenches. I have tightened as much as I dare w/o stripping it. Still leaks.

The 1st inline tee leaks as well. Tightened here as well. Better but still a leak. Ran outta patience, called it a day(grin).

Questions...

1 - Isn't the front master reservoir for the front brakes?

2 - I searched this site. Does loosening and retighten work?

3 - I am 99.9% sure I have no crossed threads. If I did, wouldn't it leak more than what Im seeing?

4 - I would tend to think, no teflon tape/pipe dope should be used due to the flared fittings.

This aint my 1st total brake job. Don't recall these issues in the past.

Thanks for your time...Don.

[Rich72C10]

When I was working on my 69 AH Sprite hard lines a few months back I had a similar leak/weeping in a few places. Loosen, then tighten back/forth a number of times solved (seated?) the connection leak/weeping problems. The hard lines on my Sprite are Nickel-copper - not sure if that makes a difference to this approach. As I felt like I needed to go tighter (leaking/weeping), I'd loosen just a wee bit and work the fitting back/forth until I went tighter. I know one of two I them ended up being really tight!

I suppose another issue you could be fighting is an anomaly on the line end or where they connect into. Like a deep scratch, burrs, or some malformation? Perhaps inspect with a modifying glass under good lighting?

You are correct, no teflon tape or pipe dope on fittings like these.

Good luck, I know your pain when dealing with brake line leaks. I didn't trust all the connections until my blue shop towel test passed. I would tear a small bit off and use tweezers to run it around each and every fitting (of course used a lot of brake spray cleaner too when I had to reset the testing). I did this for about two or three days. The previous owner ran the lines wrong and used teflon tape in a few places... not fun at all ;-)

Edit
[Rant-Off Topic]
The PO of my Sprite had ran the front/rear lines to the Master Cylinder backwards. I only figured this out because I rebuilt the PDWA (it drives the brake light in case of a catastrophic failure in pressure) and would come on randomly when I got it working. Why anyone would work on their car's brakes and make a mistake like this is beyond me and then try to deal with leaks incorrectly - which they still leaked. Man was I pissed off and still am!

Good job @don t. - 72gmc asking for advise. That's the first step getting something right [researching and asking as needed] and I hope you solve your leaking problem.
[/Rant-Off Topic]

[geezer#99]

The loosen/tighten method works best with new lines.
On older fittings copper flare washers work better.
Like here.


https://www.amazon.ca/Legines-Copper...07CHFJH38?th=1

[dmjlambert]

A friend had leaks all over the place because he bought stainless brake lines. Those are especially hard. I suggested copper flare washers and it solved his problems. I ended up going with plain steel pre-bent brake lines and I had a few connections I had to go back to and used the loosen and re-tighten method to get them to stop leaking. I loosened and re-tightened over and over about a dozen times for each connection before re-testing for leaks.

On 3/4 ton trucks I believe the front of the master cylinder goes to the rear brakes, it is on the 1/2 ton trucks the front of the master cylinder is for the front brakes.

I think it's true if you were cross threaded you would have a big leak. So you're almost there...

[tallic68]

The issues I had when I just did total brake renewal on my 68 was I ordered prebent stainless lines and stainless fittings got everything in and a couple fittings leaked no matter what I did. Found out some stainless has a different flare angle degree and 4 of the fitting I ordered I’m guessing we’re the wrong degree not the 45 degree that is standard. Replaced those fittings with run of the mill brass fittings and blamo. Sealed system. Some of the junctions had to be loosened and thigtend a couple time to finally seal but the flare degree thing was a serious issue. Just destroyed the paint on drivers inner fender.

[don t. - 72gmc]

I bought standard metal lines from one of this sites vendors. Shipped from Inline.
Bleeding brakes is the last big ticket item on the to-do list.

Kinda ticked off at the leaks. Plan to take the weekend off. Start in earnest on Monday.

Thanks much for the help.
Greatly appreciated....Don.