Braking problems.

[dantheman300z]

This is my first thread. I have recently started to had some odd braking problems. If I only press the brake once to slow down it will have no pressure and slow down terribly, then my BRAKE and ABS light will come on. If I pump the brake again the pedal will firm and slow the truck down. My truck is a 93 W250 with the a518. I read some of the thread a little bit down the page but I do not have a FSM so I do not know what the RWAL valve is. Any info would be greatly appreciated.

[PToombs]

Sounds like the RWAL accumulator valve failed on you. If you look just ahead of the rear axle on the inside drivers side of the frame you'll see a valve with the brake lines going to it and a wire. This is the valve. If you do a search you can come up with fitting numbers to bypass the valve. Or someone will jump in and list them for you. Just remove it and hook the lines together with the fittings, and unplug the black box behind the glovebox to eliminate the lights and you'll be good to go. Or you can replace the valve with a new ($) one. It's not a hard job and most of us have done it.

[dantheman300z]

Ok. I would need to just bleed the rear brakes after deleting the valve?

[PToombs]

Yup, that will do it! You'll be surprised at how much better your brakes will feel after doing it. Good luck!

[lazyjoe]

Here are the napa numbers. And it works great.
WEA 7917 & WEA 7828.

[dantheman300z]

Since I am inside and it's warm I will ask one more question. What brake fluid do the dodges run?

[Mark Nixon]

BEFORE you even start deleting the ABS dump valve, run the adjusters tight on the brakes.
As I have stated MANY times before, brake issues many times stem from adjustment and condition of the REAR BRAKING SYSTEM.
At the very least, run the adjusters up until you get a light drag on the drum, then try it to see how it performs.

There is also more than one way to trip the ABS light, with the most common being vacuum leakage that trips the vacuum sensor valve on the fender, which a low pedal CAN do, because it increases the volume of the brake booster's diaphragm.
Worse, sometimes the diaphragm leaks due to age and having been torn by over extension.

Another way the ABS light is tripped is by an internal fault in the ABS dump valve on the rear frame, or by the ABS sensor getting shorted by filings from the rear axle, at the sensor end.

Mark.

[PToombs]

Regular DOT 3 fluid.

[dantheman300z]

I deleted the valve. It worked, brakes are great! I will be posting pics of it tomorrow.

[dantheman300z]

Here is my RWAL delete job.

Went of O'Reilly's for the parts since my local Napa didn't carry them


Prices didn't change from what I read on here.


Had to get the shop warm!


Master cylinder lid gasket was a bit dirty, cleaned it up a bit.


Bleeding my brakes. The driver's side drum bleeder was rusted shut, i had to pull it out and clean it up.


You can see up top is my reroute for the brake line.


Dirty brake fluid, I tried to flush as much as possible!

[cmann250]

Let us know how that drain plug works. I intend to install one the next time I have my pan off.

[dantheman300z]

Same here. I saw it posted on here and I will probably be trying it within a week or two.

[monoblock]

I read all I could on the rear brakes and one recommendation often made is very difficult to follow. Mark (above) notes the importance of adjusting the rear brakes. But how? I read the FSM and understand the 2 screwdriver method. The toothed pawl inside the drum is designed to allow backing-off the shoes to get the drum off. The teeth on the pawl are angled so it is easy to back it off but to adjust it the other way would be impossible? The screwdriver tip would just ride up the ramp of the pawl instead of engaging positively with the teeth .The rear brakes are self-adjusting so just keep braking sharply in reverse a few times?
My plan was to slacken off the adjuster,remove the drums,clean,inspect ,lubricate and replace.When the adjusters are clean and correctly lubricated ,can they be expanded using the 2 screwdriver method ? Some other tool/trick ?
I have not touched the rear brakes because I can't figure our how to manually re-adjust the shoes as advised above.
Grateful for any further advise/clarification.
BTW the best deal I found on brake fluid for flushing the entire system was Walmart -32oz. big bottle of DOT3.Now the fluid in the system looks like Chardonnay instead of old engine oil.Cheap preservation of the seals.

[Mark Nixon]

I think you have the tooth directionality confused.
The teeth are angled so as to NOT allow the star wheel to back off, so that it's easier to TIGHTEN the brakes.
This is how the adjuster finger locks the star wheel, it drives INTO the ramp, not away from it, thus maintaining the adjustment.
For REMOVAL, all there is to use is the 2 screwdriver method, one to release the pawl, the other to back the star wheel off.

With there being no real way to gain a satisfactory grip (besides more force) on the star wheel to loosen it, if the star wheel is seized, you are pretty much SOL and have to force things apart.
In MOST cases, if you can't adjust the brakes, it's likely they'll come apart fairly easily, anyway.

Let's face it, most of us only look at the rear brakes because they have made themselves known to be a problem.
Usually by then they need much attention.

On adjusting them, the clue as to whether you're going the right way is if the tool (Brake spoon or screwdriver) slips easily, you're trying to LOOSEN it, if it "bites", with no slippage, plus you can hear the finger "click", you're tightening it.
This assumes that the brake hardware is still in good condition and that everything is installed and working properly.

I put up a posting recently with a fairly detailed description of the self-adjuster theory, which may or may not be comprehensible without actually having a brake assembly to look at.
Admittedly, I probably should do a write up with pics, to clarify things a bit more.

Mark.

[monoblock]

Here is the Post by Mark - to help others:
viewtopic.php?f=2&t=13669&p=113922&hilit=rear+brakes+self+adjuster#p113922