I have brake fluid leaking, when i press the brakes, out of the bottom of what i think is the height sensing proportioning valve

A proportioning valve is not servicable. I dont remebmer a bleeder on these. Are you sure you dont mean the master cilinder or the abs unit?

get is serviced.

its stuck in , low bed (loaded) mode. the lever is or parts in side

stuck in full load mode.

and guess what, if you bypass the valve, what will happen

the rear brake will lock, going fast and if on wet or worse roads. 10x worse. its there for a reason. to lower the brake pressure with no pickup bed load. or not heavy trailer tongue weight.



ever consider the rear brakes are bad. first. and not the valve.



service the rear shoes and slaves.

then check the bypass.



Does the truck still have the height sensing brake line bracket and line connected into the prop valve?



http://www.jeepforum.com/forum/f53/bad-proportioning-valve-any-ideas-1127468/#post10505224







here is the valve.

sold at , JEEP.



http://www.factorychryslerparts.com/products/JEEP/1988/COMANCHE/VALVE--Proportioning--VALVE--Proportioning--ECE-198789--1989--Except-France--Italy--1990--KDX--KDX-After-3-1-93--KDX-Up-to-3-1-93/4520728/52009114.html



Chysler p/n

52009114 ; 52003118



google that and find them for $75

there only 2 ways (USA answers)
they have a guage test (expensive gauge)
or replace it ,if in fact you know for sure the rear brakes are good.

i think raybestos sells this.valve rebuilt.

the valve is height measuring disconnect the link and see if its
free? is it jammed? i had a 88 from new.
i purged brake fluid every year and it lasted for 250k miles. and sold it.
so there is a bench mark on life.(best case)
did you read the fsm? yet
id does cover these tests.

try alldata.com (usa ) it may cover Commanche.

For the brake how are the sliding pins on the calipers?They should not be corroded the caliper has to slide on it so make sure they are not corroded.Lubricate the caliper slide pin.If the caliper is clean and clear you are suffering from premature wear and high peddle effort the cause is rear hieght sensing porportioning valve.Make sure the rear height suspension proportioning valve is not affected if you modified the rear suspension you will need a kit . If you did not and the height sensing valve is intact a replacement will be required. As for the High RPM the throttle actuator is at fault

I wouldn't think you would drive it at all,
until you resolve that problem

If you follow all the brake tubing,hoses,calipers etc,
you will see the fluid leaking out,has to go somewhere

If you find nothing remove the master cylinder and
see if it leaks out the valves into the power booster

Bleed the brakes, but it will probably still feel spongy. When you compress the Caliper you need to open the bleeder valve to release the pressure. It sounds like you busted the diaphragm in the proportioning valve. It is a costly mistake but one made alot now that more and more vehicles have anti-locking breaks. If bleeding and replacing the fluid do not help at all then I bet on the proportioning valve.

could be a malfunctioning height sensing proportion valve, usually located somewhere near the rear. You will see steel brake lines coming out of it and going to the wheels. Or could be air in the lines

yes you must change same, in my experience i change it

the stratus is know for clasped rear brake hoses .This stops the flow off brake fluid. try opening the brake lines at the master cylinder that go to the rear.pump up brakes first! if you got fluid than check the brake line if this is rear disc brakes on the line at the rear will be a built in proportioning valve.if drum loosen rubber hose line before the rubber part to see if you have fluid. If you do replace the brake hose! On you 74 challenger by the way i love dodge! any way on the valve there is a small button on the front of the proportioning valve that pops out it needs to be tap in lightly. also hit the brake peddel kind of hard a couple off times if that doesn't work. thanks for your question


p.s that hex bar on the is a junction not a proportioning valve .

The proportioning valve most definately can be the problem. Did you change it or is it the original? (A disc/drum system uses a 70%front/30%rear braking ratio, whereas an all-disc system is alot more even). I would first bleed the master cylinder. Then I would 'gravity bleed' the rest of the system by opening the bleeders on all 4 wheels. Do not at any point let the m/cylinder go dry. Also, do not touch the brake pedal.
Continuously check all 4 bleeders, when clean brake fluid with no bubbles at all is running from a bleeder, close it. When all 4 wheels are done, recheck the fluid level and you should be OK.
Pump the pedal to 'self-adjust' the rear calipers, then re-check the fluid level.
Any problem after that means you either have a loose connection (it's possible for a tiny leak to let air in, but not let fluid leak), a leak, or you need a new (disc/disc type) proportioning valve. I would try Summit Racing myself. Good Luck!