This will be a long thread so I give all the details to save you guys time.

I have '92 D250 Cummins 5spd, 143,000 on the odometer. About two months ago, I failed VA safety inspection due to scored rotors. Never had a problem with the truck before this, and I couldn't even tell, hear, or feel any problems with the brakes. The calipers, rotors, brake lines, master cylinder, and booster were all originial.

So I bought brand new Bendix Rotors, had them turned and pressed, and while I was at it installed all new bearings & races.

When I was working on installing the hub/rotor, I used the crappy Haynes Manual (I know, it's worthless) and for some reason followed their advice about removing the cap of the MC, then 1/3 of the brake fluid, and compressing the calipers with the bleeders shut. This should have forced fluid back into the MC, but I noticed when I did this that the fluid level of the MC never changed, and it seemed to bleed out of the sides of the booster, and the black plastic fitting on the MC with hoses attached to it (by the way, can someone tell me what that is?). I thought that wasn't a good sign.

So I ignored that, inspected the brake lines, they looked good, so I put on the hub/rotors, nice high-end HD pads, filled the MC, and go for my test drive (did not bleed the brakes yet). Everything works beautifully. No leaks, no problems. No pedal travel issues.

About 1 week later, I'm driving in heavy DC traffic, and I start hearing a little bit of brake squeal when first pressing the pedal. Then I feel that the front calipers are slightly dragging. Angry, I drive 5-10 miles home using more throttle. Brakes smoked for a bit when I got back to my driveway, and inhaling some smoke on the way back at red lights gave me a decent headache.

So I start thinking I have a clogged expansion port in the MC due to pushing the calipers back in with the bleeders shut (sediment in old/bad fluid), or just a bad MC period.

Yesterday, I go ahead and use a one-man bleeder to bleed the front brakes and flush all the old fluid out. I know the rears were good from full brake lock-ups and how well the Parking Brake works.

I take the truck for a test drive, and now all the sudden the pedal goes almost to the floor before the brakes engage. The first pump is completely soft, a quick second pump and the pedal feels normal. There are no leaks from the MC, booster, or lines. No brake warning lights come on in the truck, but I know they work because they lit up when I was bleeding the brakes. The rears will lock if I quickly push the pedal to the floor.

One unusual thing I did notice was that the front reservoir rubber cup on the MC cap was sucked down after I bled each side of the brakes. Also, if the truck is not running, the pedal seems much more firm.

Tonight I'm going to listen for hissing sounds, and check for swollen or cracked lines. I haven't checked the new pads or rotors for any damage from driving with dragging calipers, but I hope I don't have to replace them. I do have a spare set of new pads, I mainly don't want to remove the hub/rotors to have them turned again.

I've been a backyard mechanic for 13 yrs. now, mostly sports cars. I have most tools anyone would need. My garage cannot fit the truck, and one problem I have is that my driveway has a good incline to it, so I'm nervous about lifting the rear of the truck to check the rear brakes, otherwise I would have done that, which is why most of my work is focused on the front.

I need the truck for my ATV racing, so I'm nearing the point, I can't beleive I'm saying this, of taking it to a professional. But my guess is, is that they will replace a bunch of parts and not cure anything. I've heard not to bother bringing it to a Dodge dealership either because they will have it coming out worse than when it went it.

In reading other threads, I know now that I'm not alone with this problem. What scares me is alot of people seem to have replaced what I planned to replace next (MC/Booster) with no fix at all. I've seen some posts about a 2lb residual pressure install that fixes the caliper slack (that I never had before).

I don't want to replace every brake part, but I know this forum is the best place I could go for help, and thanks to everyone for giving their time to help me out. Sorry for the length, but I wanted to cover all the bases. And this is my first post, and hopefully the last.

In case anyone is taking a poll, I have the speedo problem too, but it starts working after 5-10 miles of driving, so I'm not too concerned (knock on wood).

Also, if anyone has a suggested manual thats useful, and where I may find it, I'd appreciate it.

 

Sounds to me, given the observation that fluid was exiting the booster when you pushed the calipers back that the rear piston (Runs the front brakes) on the M/C is weak and allowing fluid to bypass. If the fluid gets inside the booster it will eventually take out the diaphrames and all kinds of funny stuff happens. I wouldn't mess around. Throw a booster M/C at it or maybe look into the Hydroboost conversion. There's several threads about that in the forum.

And by the way, stick around and put your two cents in now and again, the more the merrier.

 

Love your user name, that sounds like me working on stuff.

Sounds like you have a bad master that has killed the booster. Get a new master/booster combo (AKA loaded booster) and that oughta clear things up.

 

If the MC leaks out the rear seal the fluid goes into the booster. Brake fluid plays havoc on the booster usually ruining it, Daves right get the MC/booster.

 

Thanks for the quick advice, all three of you. I'll order the combo tommorow, and hope the rain holds out this weekend. Can't say enough about how helpful this forum is, and I hope I can contribute usefully in the future. I'll post a response once I complete the install and let everyone know how this ends. Thanks again.

 

Wannadiesel
What do you mean by loaded booster

Mark

 

http://www.partsamerica.com/ProductD...pe=250&PTSet=A

 

Okay, so this weekend I finally had good enough weather to install the loaded booster. Install went well. However, when driving the brake pedal won't return to the normal position. I have to pull it back with the top of my foot.

If I press the brake and take my foot off, it will maintain constant brake pressure. Smooth and even, but the pedal won't return on it's own except for once or twice. Why would this be happening?

The brakes engage properly, and don't drag at all. I bench bled the MC, and then the RWAL, Drums, and Discs in the proper order about 4 times.

Could the caliper retainers be too tight, or deteriorating hoses?

The new MC seems to have leaked a little fluid out of the rear reservoir for the front brakes.

Also, the new rod from the booster that attaches to the pedal does seem a bit shorter (had to move the brake light switch all the way forward), can I adjust this by turning it out?

 

If the new cyl leaks any replace it, the rod has to be same lenght, can you use old rod ?

 

The new MC isn't leaking much at all, just a few drips near the top of the reservoir. I was thinking maybe there's air still in the system or maybe there's pressure build up from deteriorated hoses partially blocking the flow.

I don't think I can remove the old rod without dissassembling the old booster. If the rod can be adjusting by turning it in or out, I'm good, I just can't tell, and don't want to damage the new booster by turning it if it shouldn't be.

 

When you bleed the brakes on ones with anti-lock brakes you need to bleed the anti-lock valve on the frame rail, pass side, first. Then you follow normal bleed sequence. The fact that your brake pedal will not return on its own leads me to believe that the booster is not working properly - MC would be the next suspect. I know they are both new "don't" mean they are working properly. I once went through 3 solonoids before I got 1 that worked - and this was before they started building them in China. You might want to check the vacuum at the booster also.

Bob

 

I'm with bob on this one.

 

Yeah, I think you got a bum booster assembly. It's under warranty so take it back and make 'em give you another. The only reason the pedal wouldn't return is a defective booster.

 

Before you tear the booster and M/C out, be sure that the pedal assy. isn't binding on the pivot rod or hanger. I don't remember if these have a bolt to secure the rod to the hanger or a clip, but I have seen the bushings wear out and the rod bolts get over tightened causing the pedal to bind.

That said, if the booster input rod is a different length, it may be the wrong booster. I'd double check that the numbers on the booster match the numbers on the box and that you have the right assy. for your application.

The booster input rod length is not adjustable though you won't hurt anything by turning it. It's a ball and socket type of setup that takes special tools to dis-assemble.

 

Thanks for all of the feedback.

I do have some side to side motion on the brake pedal, so the bushings might be spent. I assume I'll have to order these directly from Dodge.

Also, the system uses a clip to secure the rod to the pedal, and I reused the old clip. Instructions for the booster say to always use a new clip.

I did put a little grease on the contact point of the rod to the pedal to try to lubricate the junction.