Brake Booster Hard Line Leak Question

[100d ua]

Hi All,

More woes after replacing my brake booster with a rebuilt unit. I discovered that the hard brake line that connects at the brake booster for the “Front Left (driver)” is leaking. If I hold firm on the brake pedal, I can see a solid drip coming out from the nut that screws into the pump. I’ve tried tightening it, but still leaks and didn’t want to force it anymore than it was.

I had a hell of a time getting that line threaded in so my thinking is it may not be seated fully correct. My plan is to disconnect the line and try re-connecting it again with the (4) brake booster nuts holding it to the wall “loose” so that I can get a little bit of leverage on getting the line in straight. If this doesn’t work, it looks like I may have to replace the line, especially if it is damaged (P/N: 473126A160).



My question is; based on the reading below I did from the master thread on our brake booster, would this leak be enough to throw the warning buzzer and ABS / Brake lights?


Am I going down the right path to repair this leak and should I de-pressurize the pump before removing the line?



“Inspecting brake flexible and hard lines.

Typically if a front line leaks or burst, it's a slow leak. Leaking more each press of the pedal, holding pedal down it's not a continuous flow to front lines. Where as rears leak faster, anytime brake pedal held down, it is a continuous flow. We'll likely see dash brake lights and hear alarm, as level drops and system has difficult reaching pressure in allotted time. Pump may run excessively long. So watch for signs.”



Source:

Brakes ...... Overdue write-up. - https://forum.ih8mud.com/threads/brakes-overdue-write-up.1230968/

 

[100d ua]

Tried to re-seat the line without any success... sigh, still leaks. Anyone replace the hard line? Any tips?

 

[100d ua]

Another quick update; I tightened the nut a little bit more and it is no longer dripping when the brake pedal is pressed.

My only concern right now, is that it appears as though there is a VERY faint seepage of liquid after going for a short drive. By this, I mean if I go on a quick drive and wipe underneath the nut with a blue shop rag I can see the faintest bit of fluid on there. I don't know if residual or what...

Now I'm in a dilemma, do I keep it as is or replace the line?

 

[baltistyle]

There’s really no tips, except making sure your mating surfaces are not scored or scratched and that the line goes straight in and perpendicular to the pump surface so there is no force on the line while you are screwing the nut down. If you’re able to truly tell where it is leaking, between the nut and the line, or between the nut and the booster, that could point to which part of the flare has the issue. If it’s the outer most part of the flare, you might want to also check the mating surface in the booster. If it’s the inner part of the flare that touches the nut, That will be replaced with the new part. I would not recommend trying to make your own brake lines, in this instance. It’s doable but more of a pain. The only brake line I made was the long one going down the driver side frame rail because otherwise you can’t fish the stock part into the stock location. Lastly, make sure you are using a proper flare nut wrench because you can very easily make the nut out of round while tightening with a standard wrench. A standard wrench will get you only so far until it makes the problem worse. Based on your update, just a couple seconds ago, this might be the issue, the wrench?

 

[100d ua]

There’s really no tips, except making sure your mating surfaces are not scored or scratched and that the line goes straight in and perpendicular to the pump surface so there is no force on the line while you are screwing the nut down. If you’re able to truly tell where it is leaking, between the nut and the line, or between the nut and the booster, that could point to which part of the flare has the issue. If it’s the outer most part of the flare, you might want to also check the mating surface in the booster. If it’s the inner part of the flare that touches the nut, That will be replaced with the new part. I would not recommend trying to make your own brake lines, in this instance. It’s doable but more of a pain. The only brake line I made was the long one going down the driver side frame rail because otherwise you can’t fish the stock part into the stock location. Lastly, make sure you are using a proper flare nut wrench because you can very easily make the nut out of round while tightening with a standard wrench. A standard wrench will get you only so far until it makes the problem worse. Based on your update, just a couple seconds ago, this might be the issue, the wrench?

That is a great point, I am not using a proper flare nut wrench. However, I am not having any issues with any of the other lines leaking besides this one to the front driver side. I guess my concern is, I don't know how much force is needed to tighten the hard line nuts and if maybe the open ended wrench i'm using just feels like i'm putting a lot of force because the nut is starting to round. I can definitely feel like it is so that's why i've been conservative with it.

I wouldn't try to make my own brake lines, the one I would need to replace is only $25 from the dealer and looks easily accessible from the wheel well.

 

[baltistyle]

So it sounds like you should try the flare wrench to tighten it properly. Yes a box wrench can work but when it doesn't, it leaks A flare wrench will allow you the most safe force.

And Ive replaced that line before in an old 100 and it’s like a 10 minute job besides the bleeding. And for consistencies sake use a flare wrench on the new pretty brake line fittings so as not to round them off

 

[100d ua]

So it sounds like you should try the flare wrench to tighten it properly. Yes a box wrench can work but when it doesn't, it leaks A flare wrench will allow you the most safe force.

And Ive replaced that line before in an old 100 and it’s like a 10 minute job besides the bleeding. And for consistencies sake use a flare wrench on the new pretty brake line fittings so as not to round them off

I will try to tighten the current line with the flare wrench and see if that helps.

Like I said, if it is leaking, it's the smallest bit of sweat coming through the lines and if maybe I can get just a teenie-weenie bit more turn in the nut it should be good to go.

Thanks for the responses!