Brakes 1979 CJ5 Proportion valve question - new

[Steffan]

New CJ owner and I’m learning a lot. I’ve had it for a few months now and have based lined it: all new gaskets on the engine, axles, etc…. All new fluids… went through the entire wire harness… on and on..

After getting it back together and driving it around the proportioning / metering valve started to leak. After reading some threads it seemed to be a thing so I ordered a new one. Of course, getting the old one off was horrible - all the nuts were cold welded to the valve: had to use a torch to heat each of the 5 nuts in order to remove… all the while not burning the whole vehicle down.

Then, the new valve’s rear outlet port was way too big for the line. They supplied a new nut nut that would mean cutting and re-flaring the line, under the vehicle. Instead I tried swapping the old outlet port with the new one along with the new o-ring. Seemed to fit fine.

Upon cleaning the old port I noticed what seemed to be a breather valve. Rubber flap held in by a push nut. I didn’t think much of it at the time until I started to bleed the breaks and it pushed out like a pimple!

Long intro into the question - what is this and what is the purpose of? Is this the way it’s supposed to behave? Thanks!

 

[TSB8C]

That is a "weep" hole. The weep hole goes to the atmospheric cavity between the 2 o-rings on the spool. There is a rubber disc and retainer that goes there to keep water and dirt out. It is suppose to blow out if either of the o'rings leak fluid. If it didn't, fluid leakage into this cavity would cause a hydraulic lock stopping the spool from moving rendering the valve inoperable. Some prop valves have them and some don't. When I replaced mine, the original had it and the new one didn't, and the new one was also the wrong size for the rear line. I used an adaptor rather than try and install the old rear section onto the new valve.

Check here for more details: Prop Valve Rebuild

 

[Steffan]

Awesome, good info… now that I know what it’s called, I can search and find a bunch of threads on the subject. Much appreciated!
So apparently, one of the internal o-rings must be leaking?
Do you recall where you found the brake line adapter?
Thanks again

 

[TSB8C]

My local O'Reilly had some. Amazon also has a lot of them in all various sizes. I believe the PV2 and PV4 proportioning valves have a 9/16-18 fitting for the rear outlet.

 

[Steffan]

My local O'Reilly had some. Amazon also has a lot of them in all various sizes. I believe the PV2 and PV4 proportioning valves have a 9/16-18 fitting for the rear outlet.

got it - back on the road! thanks!