bad proportioning valve on an 88 XJ?

we're still working on the brakes on our 88 XJ, and the only thing we havent replaced pretty much is the proportioning valve.. how would you be able to tell if it was the proportioning valve acting up?

tychotb said:

we're still working on the brakes on our 88 XJ, and the only thing we havent replaced pretty much is the proportioning valve.. how would you be able to tell if it was the proportioning valve acting up?

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When you have replaced everything else (like have too). :doh:

Propertioning valve cleaning and repair is on my to do list too.

So what braking problems are you having?

still getting no pressure when we hit the brakes, let's us hit it to the floor still

replaced the master cylinder (twice hehe), booster, etc and have gone through many, many bottles of brake fluid bleeding the MC/Brakes only thing left is the proportioning valve - how would we be able to tell if it was that acting up?

tychotb said:

still getting no pressure when we hit the brakes, let's us hit it to the floor still

replaced the master cylinder (twice hehe), booster, etc and have gone through many, many bottles of brake fluid bleeding the MC/Brakes only thing left is the proportioning valve - how would we be able to tell if it was that acting up?

Click to expand...

Did you bench bleed the Master Cylinder (MC)before installing it, and then bleed the brake lines? Sounds like air still in the lines and or master cylinder to me, or you got several bad MCs in a row. If the pedal is going to the floor it is either air still in the system, a bad MC, or a big leak somewhere. Not the Proportioning Valve (PV) causing that problem. I had peddle pressure but no rear breaks, even after bleeding that was being caused by the PV problem.

It's possible for air to get trapped in the combination valve. After bleeding the MC, crack each connector nut at the MC while some one is holding the brake pedal down. Quickly open and close nut. Repeat 2-3 times until only clear brake fluid is observed. Then move to the combination valve, starting with the lines running from the MC to the valve, followed by the lines leading to the front/rear brakes. Then bleed the brakes. Pedal going to the floor generally means air, in an other wise stock set-up.

You may also need to adjust the rear brakes.
Eddie