New Proportioning Valve leaking

[DJs74]

Installed a brand new windshield last night that my brother got me for Christmas - all went well there but the Bronco was so appreciative of the new glass that it decided to puke brake fluid over night!!!

The brake system is all new and was just recently (within the last several months) converted to front discs with a new power brake booster/MC kit that included the new proportioning valve.

I had two puddles of fluid, one below the front differential and one right under the rear radius arm nut. The fluid is leaking out of the rubber plug in the front of the valve onto the frame and running through and down the frame. I took the rubber plug off and find a hex nut with what looks like a needle / pin in the center.

Any ideas why it started leaking out of the clear blue? I have run it a lot lately but pretty sure the leak just started because I inspect things often after a healthy run and everything has been good and dry - also check brake fluid and is always full until today and had to add fluid to both reservoirs.

Is this fixable is or a new prop valve needed? In either case it is hard to get to with the booster & headers in the way.

I tried to tighten the hex nut under the rubber cap but it will not budge. All other fittings are tight and dry.

See below photo of the kit I installed.

thanks in advance,

DJs74

 

[Blue Bastard]

sounds familiar......

http://classicbroncos.com/forums/showthread.php?t=238677&highlight=prop+valve

I had to replace and relocate.

 

[savage]

Blue Bastard beat me to it.That is not a nut,its a pressure valve inside the Proportioning Valve. That thread should answer some questions.

 

[DJs74]

Thanks for the info and link guys. Obviously the seal inside this valve has failed but I don't think heat is the cause but rather maybe a poor design either with the brass or the rubber seal or maybe a seal material issue.

Coincidentally, I am a mechanical engineer and primarily a mechanical seal engineer but not necessarily a prop valve engineer so i wasn't sure what the mechanism inside was looking like.

Typically, brake fluid seal material can take operating temps of 300 - 400°F so I don't think that much (or more) radiant heat from the headers could make it into the prop valve and cause failure. A more reasonable assumption might be that the seal material selection used inside is either flat wrong or maybe sub-par and then just lets go after a while. A lot of brass valve type applications require very clean machining practices so no burrs or sharp edges are present that could harm the seal during installation and operation. Believe it or not, more than 50% of seal failures occur at installation due to improper assembly (stretched, torn, etc).

I guess I'll call my supplier and explain and see what they have to say.

Very unfortunate and a real bitch to get to

Thanks again for the info

DJs74

 

[sp71eb]

Same for me. I called the guy I bought mine from and he sent me a new valve. Very easy to install and not much fluid is lost. Still have to rebleed the brakes. Mine hasn't leaked after I installed the new plunger so hopefully they have it figured out.

http://classicbroncos.com/forums/showthread.php?t=238550

 

[savage]

It seems like a lot of people are still having issues with that style of Proportioning Valve.

 

[DJs74]

I talked to the vendor today - he said there are some issues but usually just a bad seal. I will take the valve apart this weekend and see why so angry in there. If I'm not successful, they said they will warranty the whole valve.

Hopefully its just a cut seal. The way the inside geometry of this item was explained to me, I should be able to remove the delay valve, inspect, freshen it up with new seals and reinstall.

Had two fresh puddles this morning again - I assume the brake system is normally under pressure even sitting quiet so the pressure in the system is pushing the fluid by this hateful little valve seal.

Will update as it unfolds and hopefully this time tomorrow will be fixed.


thanks again for all the input.

DJs74

 

[nate213]

my pro valve is leaking from the same spot. if i took it to a brake place, would they be able to put a different new one on? or does the early bronco require a specific valve?

 

[g8rb8t]

I'm on Pro valve #3. Pretty frustrating!

 

[DJs74]

Update:

I received the new proportioning valve about 3 weeks ago but was in the middle of other projects so had to hold off installing it. I finally got it in a few days ago, re-bled the system and so far so good - all seems well.

I received a complete assembly proportioning valve but ended up just removing the small inner valve and left the main body installed.

thanks for all the advice & replies


DJs74

 

[DJs74]

my pro valve is leaking from the same spot. if i took it to a brake place, would they be able to put a different new one on? or does the early bronco require a specific valve?

I would imagine a brake shop could do it for you but they would probably have to order the valve and you'd need to wait a while. Or, you could order one and take it to the shop and just let them install it.

It's not too bad of a job just a little tight where it is located (or at least mine is - mine is mounted to the frame right below the brake booster / master cylinder)

Good luck,

DJs74

 

[SeanT4x4]

This seems to be a super common problem. It happened to me as well, about 2 months after disk brake upgrade. I searched around and its not just us its happening to. Guys all over the chevy forums have the same problem. I decided it wasn't worth the trouble. Put a willwood inline pro valve on and lined the fronts straight to the calipers. Its worked like a dream.

 

[DJs74]

This seems to be a super common problem. It happened to me as well, about 2 months after disk brake upgrade. I searched around and its not just us its happening to. Guys all over the chevy forums have the same problem. I decided it wasn't worth the trouble. Put a willwood inline pro valve on and lined the fronts straight to the calipers. Its worked like a dream.

Thanks for the info SeanT4X4!

If it happens to me again, I'll be switching the current pro valve out for another brand. Too much trouble to keep messing with the same one, not to mention the aspect of the brake fluid on my frame paint

Can you share your Willwood P/N (just in case).

thanks,

DJs74

 

[SeanT4x4]

This is the one I used:
http://www.summitracing.com/parts/wil-260-10922

 

[Apogee]

The Wilwood #260-10922 is ported for 3/8-24 inverted flare fittings, but they also offer it with 1/8 NPT (260-8419) for use with adapter fittings, which you will need if you happen to be running 1/4" hard line for the rear circuit. Summit also has their own brand labeled version, SUM-G3905.

You can also get distribution blocks with built-in adjustable proportioning valves like the Wilwood #260-11179, #260-13190, etc.