brake problems on 92

[dpuckett]

I am now back online after a 1 year hiatius. I have had problems with the brakes on my 92 since I got it. I replaced the master cylinder 4 times, a new unit every time. SOmeone mentioned that the booster could be bad. I thought the booster just made the pedal easier to push. The last master cylinder I put on it has lasted for a week and a half. I got it pressure bled at Brakes Plus, and they were good until I got back to Missouri for a load of hay. I had to get a new driveshaft made, and it sat 3 days while the machine shop waited for splines. I put the new shaft in, and the brake pedal fell to the floor when I started it to take it for a test drive. If I pump it up, I have good brakes for about 5 seconds and it starts to fade. Have I just happened to get bad units, or is there something else I have not thought of? I bench bleed it every time, following the instructions to a T, and then bleed the brakes, starting at RR, LR, RF, LF. I have no leaks, everything but the rotors is new. I upgraded to 1-1/8 wheel cylinders and 3inch shoes in back. Other than that, I have no complaints. Coming back with 150 bales of hay was not fun, fortunately, it was all interstate, and I timed it to miss StLouis and KC rush hours. Could it be the booster? I know some of you have had a lot more experience than I in this area. THanks in advance.



Daniel

 

[Philip]

If it just falls to the floor and you do not have a leak. That is showing an internal leak around the master cylinder cups. So I would replace it.

What is the time span on the four bad master cylinders?

Did all of them come from the same store?

Were all of them in a sealed box?

Did the box look like it had been opened before?

 

[BCaldwell]

In my experiences with replacement master cylinders I have only had problems if I purchased a so called re manufactured unit same sort of problems you are experiencing go with new unit . Bill

 

[JLEONARD]

I agree about not using re-built master cylinders. I put a new NAPA one on my truck over a year ago, along with new everything else, ... bled out easy the first time and has given zero problems.

 

[sam peterson]

Forget about the booster. Thats not the problem. Try clamping off the front & rear brake hoses. If the pedal still goes down replace the master cyl. ----New Only----Sam

 

[robiR]

I had the same problems with my breaks when I finally redid them. I found out the hard way that the parts people sell out there are realy junk! I went through 3 rebuilt master cyl, and two new ones from NAPA till I finally got one that worked right! Never in my life have I had such a problem in parts! I would think that parts should go through some kind of a safty check befor anyone would be able to sell them! Anyway stick to your guns-it sure sounds like a master cyl to me, and make the auto parts people eat the bad master cyls-just maybe someday they will stop selling junk!

 

[dpuckett]

THanks guys. Sorry it has been so long getting back. I have to borrow neighbor's computer, and they went elk hunting right after I posted it.

Phillip- THis has all happened since I got it in July. I got 2 from Advance Auto Parts, and 2 from NAPA. All were "NEW. " THe boxes were not sealed, but the plastic bag was still stapled like they were from the factory. Where do I get one with a sealed box?



I did have an idea after I last posted about this. I disconnected the brake lines and plugged off the ports with the plugs for bench bleeding. Pedal went down about 1/2 inch and stayed there for 2 minutes with my 240 lbs on it. So what else is there? I had to replace the adjusting wheel retainer when in MO, shop missed that in their "inspection. " More on that later. Neighbor and I bled the brakes, and large quantities of air in the rears. I dont think th eshop even bled the rears.

You better believe I am going to make the store eat the bad cylinders. THere is no reason I should have to pump the brakes like I have to to get decent braking. I think I will try Carquest next. Then maybe a junkyard. $10 and they cant be much worse than I have been getting.

 

[Paychk]

Daniel



Do you have the RWAL system on your truck? if so the manual says proper bleed order is the RWAL valve first, then the RR, LR, RF, LF wheels. There may be air trapped in the valve. Something else, have you inspected all the brake lines? the steel can corrode and result in a pinhole or the flex-hoses could be seeping or letting air into the system.

 

[BushWakr - RIP]

Yes, bleed sequence is important with RWAL.



Bob.

 

[dpuckett]

Hadn't thought of starting at the module under the left frame rail. Will add that to my TO DO list and get back with results. Fiancee's dad says hydraulics can be funny sometimes.



Daniel

 

[Baron]

Add me to the list of those dis sastisfied with brake performance... had a re built MC installed a month ago as the pedal was very soft. ( I think I paid about $40 for the rebuilt vs $165 ?? for the new) This after new rotors installed and rear shoes checked and in good shape. Brakes worked well for a week or so and now they work but work better after one pump up or so. I am wondering if the shoes on the rear need to be adjusted tighter after this work was done?? Also I am now wondering if the RWAL valve was bled and there is air in the system... ... .

One thing I did not understand ..... what is the TEST to see if the MC is good or not?? "Clamping off the lines"??? what do you mean by that? Like screwing a plug in both rear lines at once? and the same for the fronts??? I dunno... ..... baron

 

[Wayne M.]

Our brake syatem can be real tricky! I knock on wood with my particular truck, but mid '80's-'90's fords (vans in this case) used the same RWAL system, save the master and booster.

I was invloved in 2 fleets of these vans- both school buses and ambulances- and have seen this problem many times, which is a phantom brake pedal. I hate to say it, but some 'lances never got fixed in the couple years I was at one shop. I mean we tried everything except changing the steel lines (catching air was not the problem)! Sometimes the RWAL modulator was the culprit, sometimes the master. I will note that rear brake adjustment is VERY CRITICAL here! Do you have ABS lights coming on at all? do the lights "prove out" when you first turn on the IGN?

 

[DieselBuzz]

I had to do a complete rear brake job when I got my truck. One drum wore soo much that it actually cut a ring off of itself! I did the 3" pads, drums and larger cylinders. I also put new pads on the front. The brakes never did seem right until I bled the RWAL valve along with the others. No more pumping, no more lights, it's much improved.

Art

 

[dpuckett]

Jellermeyer-



I meant that I unscrewed the lines coming out of the master cylinder and put in the little blue plugs that I used for bench bleeding in place of them. Since there are no leaks in the lines, wheel cylinders, or calipers, that leaves air SOMEWHERE. The rear brakes "whoosh" against the drum for 360 degrees, and I have to put a bit of effort behind it. The truck stops just fine empty if you know what to expect. But I have other priorities- getting 93 flatbed going- so I will have to put this on a middle burner. I am going to take the pump off this pickup and put it on my 93. See that saga under '93 wont start'



Thanks a lot guys. Now that hunting season is over, I will try to get on here a few times a week. Not that I am an expert, but I can add my . 02 worth.



Daniel

 

[Wayno]

I must be lucky when it comes to bleeding the brakes. I flush out my brake fluid once a year and I have never open the bleeder valve at the RWAL valve. The only problems I have is pulling to the right which was cause by a bad right shock and I have had problems with getting a good master cylinder. I bought a new Wagner master cylinder and have not had a problem since. Get a new Wagner or Bendix master cylinder. I also took the proportion valve off and put it in the trash. Keep those back brakes adjusted.