Steel brake line replacement

[Dechion]

I replaced my Master Cylinder a week or so ago, then finally managed to get the damn real bleeder valves unstuck (and replaced what was left of them).

 

I go to bleed and what do I find?

 

Busted a brake line on the drives side about halfway back.

 

I have replaced steel line on other trucks before by removing the bad section plus a few inches and splicing in steel tubing with compression fittings. Any known issues with using that method on our systems? (89 MJ in my case)

 

I don't think it will be an issue, but it never hurts to ask a room full of folks that know what they are talking about.

 

~Brad

[ParadiseMJ]

My take on this would be to replace the whole line and check the condition, carefully, of your other lines. If one line is rusted or corroded out there is a good chance that other lines are having the same issue.

 

I really don't have much in the way of rust issues in CA, but I still have to deal with regular wear and age of things made of steel. I know it may be a beetch to go thru the whole system but it's worth it on the safety end.

[Pete M]

splicing brake lines is a BAD idea. the system can produce way more pressure then those compression fittings can handle. plus as paradise said, if the line is bad in one spot, it's likely bad in others too. You need to replace the entire line. You can either get some bulk tube and rent a double flaring tool, or you can buy the long lengths of pre-flared lines and just connect them together. I've done both and the pre-made lines were easier. also I highly recommend a small brake tube bender. :thumbsup:

[Dechion]

Oddly, when I said compression fittings I was talking about the kind you use a flaring tool with, as opposed to the simple brass ones with the ferrule. My bad for not making that more clear, I should have called them flare nut fittings (I think).

 

You have a really good point about going through all the lines, that is definately on my agenda for today, though parts is more of a Friday thing. (gotta wait for the boss to shake his money tree at me so I can have some too.)

 

One thing that just occured to me, the line that I am working on is going from the proportioning valve towards the back. There are two lines running parallel to each other. Every other brake system I have worked on had one line running to a "T" connetor near the rear differential.

 

Is that the case here as well or do I have seperate lines from the proportioning valve to each wheel?

 

I know I can just look, but I am stuck at work and can't at the moment. I also can't seem to find a hydraulic diagram online.

 

~Brad

[Pete M]

one is the main line running to the rear. the other is the emergency line running to the rear. the front valve is only a splitter or combination valve (not a proportioning valve), and in the event of a loss of front brake pressure, it diverts rear power to the emergency line, which bypasses the rear height sensing valve (which is our proportioning valve) to give full power to the rear. run a search for "prop valve" or something like that and you should find the various methods of removing the rear valve if you choose to do so.

[Dechion]

Thanks much.

 

Now to crawl under there and figure things out.

[Eagle]

I have replaced steel line on other trucks before by removing the bad section plus a few inches and splicing in steel tubing with compression fittings. Any known issues with using that method on our systems? (89 MJ in my case)

First, compression fittings are not for brake lines. Use the proper flare fittings.

 

Second -- I did what you are suggesting on my '88 Cherokee a few years ago. Replaced a foot or two of rusted line where it had popped. Friend came over to work the peddle while I bled the brakes. As soon as we had most of the air out of the rear and started to get a firm peddle -- it popped again, about 6" ahead of the new section.

 

Don't fool around. Brakes are important. Just rip it out and replace the whole thing.

[Dechion]

I was doing a bit of checking and I can get cut to length, bend it your self, steel brakelines at a local shop for $25 a piece.

 

I am thinking $50 for noth and knowing that I never have to F with it again is cheap at twice the price.

[Dechion]

Alrighty, got up under there today (huzzah for payday) and started tinkering around.

 

Holy hell what a rusted mess everything was. :eek:

 

After seeing what I had to work with and reading up on here for a couple hours I decided to replace everything from the master cylinder to the wheel cylinders. I also decided to remove the load sensing valve from the circuit whil I was at it. Baded on it's condition it wasn't doing much anyhow.

 

Today saw everything pulled off and parts bought, tomorrow should see everything installed. I'll try for pics once I am done. :yes:

[Eagle]

Sounds like a plan. Carry on, and happy braking.