Leaking brake line at Prop Valve after installing new SS lines

[HokieCJ7]

Hi,

I have an 83 CJ7 that I had previously added a power brake booster to. Recently I purchased and installed a set of SS brake lines, but I cannot for the life of me get one of the lines to stop leaking.
Where the rear brake line input attaches to the proportioning valve from the MC, I have a leak. No matter how many times I have removed this, and tried to tighten, it still leaks. I do not know what to try next, although I know that what I have going on now does not seem to be working.
If I crank down the brake line as hard far as it will go, which is a lot further than the other lines have seated themselves, I am still getting leakage coming up from the center of the connection, around the brake line fitting.
I am not sure if this is relevant, but when I ordered the brake line set, I ordered the lines for power brakes, as I was told by Classic tube that if I have power brakes, that is what I should order. They could not give me any details of the differences between the two sets, so I am not sure if this is now playing a role or not.
I am thinking that the problem is either with the brake line, or proportioning valve. I am thinking of just getting some brake line tubing, from Napa and trying to run that line instead of the SS line to see if it takes car of the problem.

I believe that the line coming off of the MC is 9/16, and going into the prop valve is 7/16, so I will probably need an adapter at one end of the line. What size line should I get, and what would be the size of the fittings?
Any other thoughts on what I might want to try?

Thanks

 

[Torxhead]

It is possible that there is some sort of crud located on the mating parts, this would prevent a seal from being made. Or maybe a defect on either of those two parts due to poor manufacturing. I don't think there is any difference in the type of brake line used between the manual and power brakes other than the length of the lines to compensate for the booster.

 

[HokieCJ7]

It is definitely a possibility that something is not allowing them to seat properly. Although the line itself looks fine, I took a mirror and tried to look down into the prop valve opening, but as it still had some brake fluid in it, and my old CJ mirror was dirty, I could not get the best look to see if it was completely clean, or if it looks damaged. What is odd is that I could tighten the line down, basically until it bottom out, although I had to use a lot of force to do this….
I just want to be sure that the lines themselves, other than their length could be different and causing this issue. It seems like a stretch, but at this time, I would be willing to consider anything.

 

[Torxhead]

HokieCJ7, The proper term for that connector is called a compression nut fitting, or thats what I call it. The tube sizes are measured on the outside diameter, The front brake size is 3/16" and the rear one is 1/4". I think you should notice just how the seal is formed at the contact surfaces. Another possibility is that piece of crud that I was talking about could now be embedded into the soft brass of the prop valve at the location of where it seals, this can be checked by a visual inspection. If this is damaged, a good brake shop might be able to fix it or you might have to purchase another prop valve. Another thing to look at is where the seal contact surface is on the brake line, like I said there could be a manufacturing defect, which can be repaired.

 

[Purple77CJ7]

If you ordered ss lines they can not be double flared. They use a single flare at a different degree angle, I believe it is 35 degrees. If I remember double flare for brake lines are 45 degrees. You would have had to have the fittings on the prpotioning valve made with the same flare angle. That can cause leaks with two different flares. Changing to regular tubing from NAPA as you stated will work.

 

[BajaEdition]

as mentioned about the flare, original lines are double flared, if the new one is not nothing will help till you get the new line. There are other style connectors but you are going have to get the right type and the right style to keep it from leaking.
I have built a few brake systems on jeeps starting from scratch, you have to get used to the fact that sometimes you are going have to search for an adapter fitting to get things to work.
I had to adapt size and type for my new P valves. to get to fit the Double flair size I was using on the rest of the jeep

 

[Old Dog]

I put SS lines on my 83 without any leaking problems so I don't think it has anything to do with the flares. But it could be a bad flare.

 

[BajaEdition]

Yes old Dog but he has non stock parts in there

I know that not all connection types are Double flair, some are single flair and some are NPS

those all need to be addressed when buying new lines, what were the fittings on the old lines

 

[IOPort51]

I would be on the phone to the people I bought them from asking for another line. The strange thing is only one line is leaking at one end. this leads me to think the flair, whatever it is, is the problem. Or that the PV has one bad port.

I would think that if the SS lines were not double flared they would not work anywhere. I wish I knew more about this, every time I have anything to do with brake lines it turns into an ordeal.

 

[85cj8]

Had a new but leaking stainles rear flex line on my sons mj .swapped out for another new line and no more leaks ,call the vendor .

 

[HokieCJ7]

Thanks everyone for your help. I ended up taking off the propr valve and realized that the one fitting that was leaking was all "buggered up". I ordered another propr valve, and am in the process of installing this. Fingers crossed, it will solve my problems!

 

[Torxhead]

Fingers crossed is right!