Brake fluid coming out of prop valve sensor on top??

[xj92]

I recently switched over to an XJ proportioning valve and removed the height-sensing valve from the rear. I now only have one line running all the way back to the rear wheels, and I can bleed the rears just fine and it appears to be working correctly in the rear. I went to bleed the fronts though, and could not get any fluid at all to come out of either side. Then I noticed it was leaking fluid from the prop valve, coming out the top of the sensor where the wire connects. I removed the sensor and put in a different one with the same results. There is no o-ring or anything in where the sensor goes, is there supposed to be? Any ideas?

 

By the way, I'm pretty sure all the lines are connected correctly, it's kind of hard to connect them in the wrong place (referring to the master cylinder to prop valve lines, and the front hard brake lines to the prop valve).

[mvusse]

Did you have front brakes before the valve switch? It is possible the lines are clogged. It is also possible a port on the valve is clogged.

 

If fluid is leaking out somewhere, there's pressure. Either the pressure is not making it's way to where it needs to go, or something's hooked up wrong.

 

As for the fluid leaking out, NPT threads are designed to seal tightly, and should not leak. If they don't seal perfectly, some loc-tite should do the trick. Don't use teflon tape on brake system fittings, as it is possible to get pieces inside the lines causing all new problems.

[xj92]

I had front brakes before the switch, but the Jeep sat with dry lines for a few weeks while I was doing other stuff before I put the fluid back in. I believe the fluid is coming up through the sensor where the wire connects, not around the threads. Since neither front brake will pull fluid, I suppose the best place to start would be to remove the line from the front reservoir part of the m/c to the prop valve and make sure it's not clogged....unless there's something I'm not thinking of.

[Wildman]

There's a very good chance the XJ proportioning valve you installed is bad.

 

Here's A very good 'How-to' for rebuilding / bleeding the XJ valve. It's possible that some thing might have gotten into the valve while you were changing it out.

[Eagle]

Then I noticed it was leaking fluid from the prop valve, coming out the top of the sensor where the wire connects. I removed the sensor and put in a different one with the same results. There is no o-ring or anything in where the sensor goes, is there supposed to be?

You mean on the plunger that activates the brake failure warning? Yes, there should be two o-rings on it. One on each end, IIRC.

 

Wildman, I looked at the link you provided, and I don't understand what he's going. He removed the internal o-ring, that I understand. But when he reassembled, he installed the spring. Everyone I know of who has done that mod (remember, kids, that applies ONLY to the XJ combination valve, NOT the MJ) removed the spring and pushed the plunger as far into the nut as possible. If the object is to allow full brake flow, in reality I don't see any reason to even have the plunger in there. I'm seriously considering removing the guts from mine and just mounting a bolt with an o-ring to close of the forward end.

[BLHTAZ]

I would do the simple things first... Disconnect the lines to the front at the valve and see if there is output at that point first. Then disconnect the other end of the lines and try to blow air through it to see if the line is blocked.

[Eagle]

Here's the photo of an MJ valve body that I sectioned. The lower part is different from the XJ valve. but the upper part with the slider that triggers the plunger switch for the warning light is the same