All,
I have a 1988 with a little over 150K on the odometer.

Trying to bring it back as it has sat for a number of years (~5) after my MIL dropped it off at my place.

Anyways after I got the engine running and typical tune up and fluid needs I have ran into something that has me scratching my head.

Originally, after the engine was cleaned up, the brake lines were shot. I replaced 3 out of the 4 lines. The fourth looked newer and solid so I left it alone.
I rebled all four bleeders with my power brake bleeder. The brake pedal was super hard to the point that I had to stand on the brake pedal to get it to slow down at all. The pedal was up, did not go down much when applied, and I am a bigger guy and I mean I had to stand on the pedal to get things to slow down.

So figuring my power assist was acting up I went searching for obvious issues like a bad vacuum line etc. I found the hose going to the power assist disconnected.
I put that back together and my brakes felt normal if not slightly soft (very acceptable). Front Passenger Caliper seemed to stick slightly, hightlighted as the rack and pinion needed replacing (leaking and bad inner tie rods) but after putting 2 tanks of gas thru the thing and a new rack it seems to have cleaned itself up.

Now almost thru the third tank,things have went to the other extreme and things are now super soft and I am not stopping any longer. Was not all of a sudden but gradual it seems. A Double step on the pedal bring things to a full stop but its not a dependable stop...glad I live in the country. Fluid went down slightly if at all in these three tanks. Took it out for a 50 mile trip to the scrap yard to haul some farm rubbish and used no fluid but seems like its just getting worse to stop.

I have checked, today, the rear shoe/drum setup and it looks like new hardware and the adjuster seems to move and function as expected. The shoes are probably half down... there is for certain meat on the shoes. The Pads up front are in a similar condition.

I am considering rebleeding everything again and testing each wheel separately again. I have a new Master Cylinder which I am considering throwing on the vehicle...Anyone have any suggestions or Ideas?

Thanks,
Chris

 

Try bleeding first, and also manually adjust the rear brakes. The shoes should JUST rub when properly adjusted. See how your brakes feel.

 

All,
I replaced the master cylinder (hey I had it already and its a good Dorman - New - I bench bled it) , rebled the whole brake system (twice), and confirmed the rear adjusters. The drums are tight to the shoes... have to rotate the drum slightly to get them on.

While it seems to stop again I should have a solid pedal, based on the bleeding/etc, and I feel I do not. I feel I am about back to where things were maybe 3 fuel tanks back and I do not feel confident with things at all.

So I started to look the brake system from back to front and whats going on and I checked the pads and shoes again. The drums look good and the wheel cylinders are not leaking and the drum area is very clean. I am going to get new front pads...while there is still some meat on them I feel they have less than a season left to them and its better to do it now than when its 0 or worse out. I might see if the local parts store also has the shoes as well just for a visual to confirm its thickness but looks to be better than a 1/4 inch or more...would not say 1/2 inch and they are not oil soaked or look bad.

Another thing I noticed, thought to mention, is I have a brake light on. There are no engine or maintenance lights on. I previously assumed the brake light was related to something in the emergency cables as they feel like they may have rusted out. Common in my neck of the woods.

After closer look, the emergency brake cables seem to be separated but the cables and their ends look ok but its missing the "connectors" for the cables. As in the Cable Split, I assume is in a "Y" layout. I am uncertain of the name but basically the metal plates holders that the cable ends go into then you adjust the tension on the cables. If anyone knows a source for those I am not seeing them quickly. A name would probably be a first step.

I assume that this vehicle has a propotioning valve around somewhere on the vehicle and is now assumed to be probably the reason the brake light is on as the Master Cylinder has no electrical. I looked under the front hood but not seeing it. I believe I read its tucked in the back somewhere. I assume its working as I have fluid from all bleeders but I would like to locate and confirm the electrical connection. Hopefully the wire or something has popped off. Anyone familiar with the location of the proportioning valve?

Again thanks for the help and responses,
Chris

 

Do you have a firm pedal, or does it feel spongy? Prop valve should be shortly below the master cylinder somewhere..... It isn't very big, and may have a couple solenoids on it as well.

 

Yes, it's to the front of the MC and kind of tucked in with the ABS apparatus.

 

I think this is the part 'Mopar 4397826 Valve-Meter & Warn Brake'

 

All,
Sorry its been a bit but the weather, work, and family functions have prevented me from working on the Dakota.

The Bendix Brake pads arrived late yesterday and today its supposed to be in low to mid 80's with a small chance of rain. So hoping to get out on it this morning.

I plan to get out and swap the pads. I am wondering if the calipers are allowing air in the lines but no fluid out. Years ago I had a vehicle do this when the pads wore down.

The brakes felt firm to me initially. Over the last few days just using the vehicle to pull a few small trailers out of the pole barn and around the farm the brakes have gotten soft again. No fluid appears to be lost and no fluid can be seen leaking/spraying/gathering anywhere. So something must be letting air in...I would be surprised if any air was in the lines when I did them last time but twice in a row I would think is a low possibility.

The brake proportioning valve I am not seeing. Keep in mind I replace the lines but followed the original layout. So today, I plan to trace the lines, confirm layout front to back and double check everthing. Honestly I am not ruling out anything as the previous owner rigged a few other things...why not brakes as well.

Thanks everyone,
Chris

 

bronze,
There is no ABS in this vehicle...its a 1988...at least that I can find.

Thanks,
Chris

 

Is the pedal soft, or just excessive travel? If you pump it up, does it get firmer?

 

All,
I have found a few things that may explain some of my situation...long winded sorry...

Lets start with I have changed the brake pads. They needed it after looking things over. They were not to metal but they would have been in a month.

I started tracing the lines. I have included a couple images to help in my explanation.

The first image below is the layout of brake setup I currently have or found. I found the Main Proportioning Valve but it was on the drivers side tunnel under the car (cab) about half way to the fuel tank before the filter.The biggest thing is someone has bypassed the main proportioning valve to the rear connection. There is a new line that someone put in (probably my MIL) that goes from the master cylinder directly to the Height Sensing Proportion Valve in the back of the vehicle. So this vehicle has two proportioning Valves. A Main and the Height Sensing Valve. I tried to document the lines where green is the new lines and Pink is the Bypassed line and I should add I now have a leak (orange) in one of the old lines that appeared after I have removed a bunch of the "dead" old line that was in the way. The image in this thread does not show the leak.


Below image is the Main Proportioning Valve. - The Top Second from the right connection now has developed a Small leak. The Bypassed line or the line that is not attached to anything is the back one (left most). Yes the Proportioning Valve is not fully closed/connected. It goes up and over the tunnel but has been cut. The lower line goes back to the Height Sensing Proportioning valve and is still connected. This line looks quite rusty its whole length...so Not sure if its actually housing fluid or not...I am not sure what it actually does 100% (return line?) as the Bypassed line goes into the Height Sensing Prop Valve and a single line goes to the Rear T that supplies brake fluid to the Wheel cylinders (Rear Brakes). So this third line I would be interested in knowing more on what it does exactly in the system or what the proportioning valve not being fully connected would do.


Image below is the Rear Height Sensing Proportioning Valve - Notice the new lines the copper color one is the Bypassed line discovered going from Master Cylinder directly to the Height Sensing Line.



Below is a unmarked up page copied from my 88 Factory Service Manual for reference.



As I have a new leak, created from tracing and removing the old useless lines, I believe the plan should be as follows (To return things back to factory brakes);
1) Remove the rest of the old lines and get them out of the way. (I believe there are 2 chunks left)
2) Remove the Front Main Proportioning Valve from Tunnel. (I am removing the Proportioning valve as the connections are quite rusty and I plan to cut all lines out/off to get them off the Prop Valve easier to try and salvage the Prop Valve) I will have to replace both Rear Lines as they are either Bypassed or are rough shape. Might be able to salvage the Bypassed line as it looks to be in good shape for use in another area. If not I have a coil and half of brake line. The Front line main coming in from Master Cyliner for the front is now leaking and lets be honest there is just the last line remaining that is like 2 feet in length that appears original. (it will probably spring a leak or not come off Peacefully - so might as well do a clean sweep of things)
3) Install Proportioning back to the vehicle (Debating on where as its current location sucks but I probably will put it back where it was located originally) Under the Master cylinder looks to be more Convenient but the bolt up in the location may be easier to mount etc.
Fronts
4) Remove the current leaky line from Vehicle (going to Master Cylinder) and replace the line. The line in question is coming from master cylinder (rear Connection) to main prop valve Top Center. This connection handles the fronts from Master Cylinder.
5) Replace line going to front T to Main Prop Valve (Front Most Top Connection). Everything in fronts would be new.
Rears
6) Replace lines (2) going from Main Prop Valve from Height Sensing Prop Valve. Back Most Center of Main Prop goes to Top Most Height Sensing Prop Valve (Copper line Currently). Bottom most of Main Prop goes to Bottom of Height Sensing (Old Rusty line). The line from the Height Sensing to Rear T is new already as well as all the remaining rear.
7) Rebleed entire system.

I guess my only concern is once I have the Main Prop Valve off is there any way to test it (why did they bypass in the first place)...I am not seeing this prop valve available new otherwise I would consider replacing it. Previously anytime I ever had a Prop Valve Problem a small hammer and a couple taps alway got things going. The Old connections on the Main Prop Valve will need to be wire brushed, Deep Creeped (WD40), and possibly warmed with a small torch if I am unlucky. Will use a 6 point deep well Socket as I will do a clean cut of the line. That Rear lower connection on the Height Sensing prop Valve looks to be in a similar state of affairs.

Thoughts or suggestions? Do you think the setup caused the lines to get spongy over time or do you think that now leaky line was somehow to blame?

Thanks everyone,
Chris