brakes gone then back then gone
03-13-2013, 05:50 PM
#16
Administrator
If you have 4WABS, I just looked on Rock, they list the same module from 97-99 in both gas and diesel, at least 1/2 and 3/4 ton, didn't check, but I would bet 1 ton is same. I would scour your local junkyards for one rather than spend that kind of coin.
First step is to identify what type of ABS system, you can either look under the hood for the tag, or simply see if you have ABS sensors on your front wheels. The 4WABS hydraulic unit is pretty big compared to the 2WABS which is just a little aluminum block with a solenoid and a steel accumulator, right next to the combination valve by the MC. I think the 4WABS module is mounted to the inner fender.
03-13-2013, 06:35 PM
#17
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ok... so I have RWAL, not ABS.
I installed the new m/c and guess what? it's better but not fixed. at first, same thing happened: pedal sinks almost to floor then rear brakes engage, no front brakes. then release pedal, slow to rise, but then full brakes come on second time depressing pedal. full brakes will stay as long as i keep the pedal down and will come back after releasing if it hasn't been too long, but then if enough time has passed, it will go back to dropping to the floor again when first stepping on the pedal, then back to full again after releasing and pressing again.
picked up the haynes manual and did some reading. sounds like the culprit could also be what they call the combination or metering valve, which i believe is what most folks around here call the proportioning valve (not to be confused with load sensing valve). although, they say that if the valve stem protrudes when the pedal is depressed, then the valve is working properly, which mine does. i'm still suspicious though because the manual says, "the metering valve holds off fully applied pressure to the front disc brakes until the rear drum brake shoes are in full contact with the drums". This is the only thing I can find that says anything at all about cutting the front brakes out.
I need to look at how the lines run again, but it appears that the front brake line exits the metering valve and goes straight to the calipers, so unless it is a computer controlled thing, it doesn't seem that the RWAL valve could do anything to cut out the front brakes?
does this make sense to anyone???
then there are the wheel speed sensors, and I'm not sure I understand their role exactly, but I'm not sure if the way my truck is acting points in that direction... if they were malfunctioning, could they send a signal that would cause no front brakes?
I installed the new m/c and guess what? it's better but not fixed. at first, same thing happened: pedal sinks almost to floor then rear brakes engage, no front brakes. then release pedal, slow to rise, but then full brakes come on second time depressing pedal. full brakes will stay as long as i keep the pedal down and will come back after releasing if it hasn't been too long, but then if enough time has passed, it will go back to dropping to the floor again when first stepping on the pedal, then back to full again after releasing and pressing again.
picked up the haynes manual and did some reading. sounds like the culprit could also be what they call the combination or metering valve, which i believe is what most folks around here call the proportioning valve (not to be confused with load sensing valve). although, they say that if the valve stem protrudes when the pedal is depressed, then the valve is working properly, which mine does. i'm still suspicious though because the manual says, "the metering valve holds off fully applied pressure to the front disc brakes until the rear drum brake shoes are in full contact with the drums". This is the only thing I can find that says anything at all about cutting the front brakes out.
I need to look at how the lines run again, but it appears that the front brake line exits the metering valve and goes straight to the calipers, so unless it is a computer controlled thing, it doesn't seem that the RWAL valve could do anything to cut out the front brakes?
does this make sense to anyone???
then there are the wheel speed sensors, and I'm not sure I understand their role exactly, but I'm not sure if the way my truck is acting points in that direction... if they were malfunctioning, could they send a signal that would cause no front brakes?
03-14-2013, 09:09 AM
#18
Administrator
If you have RWAL only, there are no wheel speed sensors. You can verify this by looking.
The way the RWAL works is the solenoid activates and allows the fluid into the accumulator, thereby not giving you rear wheel braking. If the rear brakes have no pressure, then the metering valve also holds off front apply, make sense?
Get to a boneyard and grab a ABS valve and try it, I am reasonably sure this will solve your problem, because your condition sure seems to mirror what I went through.
PS throw that stupid Haynes manual away ( OK, maybe not throw it away, but still ) and get yourself a real FSM.
35 Bucks on CD from Genos garage. Your sanity will thank you for it.
The way the RWAL works is the solenoid activates and allows the fluid into the accumulator, thereby not giving you rear wheel braking. If the rear brakes have no pressure, then the metering valve also holds off front apply, make sense?
Get to a boneyard and grab a ABS valve and try it, I am reasonably sure this will solve your problem, because your condition sure seems to mirror what I went through.
PS throw that stupid Haynes manual away ( OK, maybe not throw it away, but still ) and get yourself a real FSM.
35 Bucks on CD from Genos garage. Your sanity will thank you for it.
11-11-2015, 02:57 PM
#19
OK, so what happened?
Arroyojim - did you find a complete cure in some form?
I'm not sure I've got the identical issues, but quite similar. The dually definitely needed a new MC a couple of years ago now (but less than 10K miles ago, since I drive it very little) but for years now, it's done this occasionally-scary thing that I've just lived with thus far because I couldn't find the cause, where all power-assist drops out abruptly. No problem except when it happens in a close-quarters semi-panic stop. Sometimes it happens when I've got a little more momentum - no power for a second or two - and then there's this noticeable sense of a lag before the rear brakes actuate, with a sort of heavy clunk, as if the rear axle has just been snagged by something. Yikes, I usually say to myself...did anyone else around me hear that?
Brake warning light never goes out anymore, but I think that's because my pads are quite thin, and on my immediate to-do list.
But here's the thing: with months of daily rain recently, my former mango-shade-tree "workshop" is an impossible mud-bog that also happens to be at the top of a steep dirt/gravel driveway that even "six-wheel-drive" doesn't work on anymore...so now that I suddenly need to be driving the truck for work, it's gotta be time for me to fork over the $$ to get it done in a real repair facility.
But if there's one thing I want to avoid in that process, it's being a victim of a shotgun-fix strategy, where that mechanic may know little more than I do about what's causing the problems, sell me on the diagnosis that my ABS module needs replacing, then call to tell me - as I mill around somewhere I don't want to be, waiting to get the truck back - that there's "also" a problem with the accumulator and I really need to replace it, and... hey, maybe that rear speed-sensor should be changed while we're at it, 'cause you don't wanna go partway on these things, sir...
I guess all I can hope for is an accurate estimate. Pointers welcome.
I'm not sure I've got the identical issues, but quite similar. The dually definitely needed a new MC a couple of years ago now (but less than 10K miles ago, since I drive it very little) but for years now, it's done this occasionally-scary thing that I've just lived with thus far because I couldn't find the cause, where all power-assist drops out abruptly. No problem except when it happens in a close-quarters semi-panic stop. Sometimes it happens when I've got a little more momentum - no power for a second or two - and then there's this noticeable sense of a lag before the rear brakes actuate, with a sort of heavy clunk, as if the rear axle has just been snagged by something. Yikes, I usually say to myself...did anyone else around me hear that?
Brake warning light never goes out anymore, but I think that's because my pads are quite thin, and on my immediate to-do list.
But here's the thing: with months of daily rain recently, my former mango-shade-tree "workshop" is an impossible mud-bog that also happens to be at the top of a steep dirt/gravel driveway that even "six-wheel-drive" doesn't work on anymore...so now that I suddenly need to be driving the truck for work, it's gotta be time for me to fork over the $$ to get it done in a real repair facility.
But if there's one thing I want to avoid in that process, it's being a victim of a shotgun-fix strategy, where that mechanic may know little more than I do about what's causing the problems, sell me on the diagnosis that my ABS module needs replacing, then call to tell me - as I mill around somewhere I don't want to be, waiting to get the truck back - that there's "also" a problem with the accumulator and I really need to replace it, and... hey, maybe that rear speed-sensor should be changed while we're at it, 'cause you don't wanna go partway on these things, sir...
I guess all I can hope for is an accurate estimate. Pointers welcome.
11-12-2015, 10:11 AM
#21
Well, it does drop IIRC, but not rocklike. Hits a very solid point, but...lower to the floor? I will have to drive it shortly and will do a better job of data-collection...I think my memory of specifics of those events is obscured by momentary panic.
Very recently it *seems* like it's abruptly started bottoming out lower to the floor, and my thought on that was that only one circuit is working. I was so sure I'd lost another MC or maybe a wheel cylinder that I drove up to another place where I had my brake-fluid stash before I even opened the hood - and of course the fluid was well above where it would have indicated I'd been losing it somewhere, so I didn't bother adding any.
I did recently swap out wheels all around, giving me an embarrassingly-rare glimpse of my front pads, and they're thin, but I don't think at "don't drive it" thin. There's definitely no metal-on-metal yet, and this is probably just another item that's gotta be fixed soon, vs. the cause of any hydraulic ills...right? Quick googling didn't get me any authoritative min thickness, though some cited 3mm - what say you, Patdaly?
1230PM will find me sitting in a greasy old-magazine-encrusted brake-and-tire shop lounge in the industrial zone, where I will probably eventually collect an estimate and not actually get any work done just yet.
BTW I used to have a friend that made what I thought was a pretty convincing argument to NOT resurface one's rotors, as long as there wasn't some horrifying gouging or warping, or if they were too thin, of course. His thinking was simple, in that similar slightly-irregular wear will of course recur, so we might as well just let the new pads bed in to the existing wear-pattern on the rotor, save some metal, and avoid the need to remove/cut the rotor...
Very recently it *seems* like it's abruptly started bottoming out lower to the floor, and my thought on that was that only one circuit is working. I was so sure I'd lost another MC or maybe a wheel cylinder that I drove up to another place where I had my brake-fluid stash before I even opened the hood - and of course the fluid was well above where it would have indicated I'd been losing it somewhere, so I didn't bother adding any.
I did recently swap out wheels all around, giving me an embarrassingly-rare glimpse of my front pads, and they're thin, but I don't think at "don't drive it" thin. There's definitely no metal-on-metal yet, and this is probably just another item that's gotta be fixed soon, vs. the cause of any hydraulic ills...right? Quick googling didn't get me any authoritative min thickness, though some cited 3mm - what say you, Patdaly?
1230PM will find me sitting in a greasy old-magazine-encrusted brake-and-tire shop lounge in the industrial zone, where I will probably eventually collect an estimate and not actually get any work done just yet.
BTW I used to have a friend that made what I thought was a pretty convincing argument to NOT resurface one's rotors, as long as there wasn't some horrifying gouging or warping, or if they were too thin, of course. His thinking was simple, in that similar slightly-irregular wear will of course recur, so we might as well just let the new pads bed in to the existing wear-pattern on the rotor, save some metal, and avoid the need to remove/cut the rotor...
11-12-2015, 07:56 PM
#22
Well, there's ONE shop I won't be doing biz with.
Breakout was thus:
Front pad change: $ 311
(asked for no rotor turning - not sure if he included that anyway)
Front rotors, if replacements needed: $292., EACH
Rear shoes, with drums turned: $ 389.
Oh, and "shop supplies," $25.
Grand total - $1370, assuming both rotors need replacement (but a relative bargain at $700 if NOT.)
And that gets me zero in the realm of "why do my brakes do that weird thing that they do" diagnosis - it's just the appetizer selection.
What about their heavily-promoted $269 lifetime-brakes deal**, you ask?
**per axle, because, hey, what about your Segway?
--------------
I may have to rethink my plan to avoid the whole working-in-the-mud-bog-at-the-top-of-the-steep-muddy-slope plan, at those rates.
Breakout was thus:
Front pad change: $ 311
(asked for no rotor turning - not sure if he included that anyway)
Front rotors, if replacements needed: $292., EACH
Rear shoes, with drums turned: $ 389.
Oh, and "shop supplies," $25.
Grand total - $1370, assuming both rotors need replacement (but a relative bargain at $700 if NOT.)
And that gets me zero in the realm of "why do my brakes do that weird thing that they do" diagnosis - it's just the appetizer selection.
What about their heavily-promoted $269 lifetime-brakes deal**, you ask?
**per axle, because, hey, what about your Segway?
--------------
I may have to rethink my plan to avoid the whole working-in-the-mud-bog-at-the-top-of-the-steep-muddy-slope plan, at those rates.
11-12-2015, 08:11 PM
#23
Patdaly (or other RockAuto shoppers)
I'm browsing at Rock, thinking I will prolly order up a worst-case collection of brake parts to minimize the emergency-trips to NAPA, always on a Sunday afternoon, just when they're closing... What's your wisdom about Rock's vast rotor selections? Looks like they're available with or without the snout, many options, and pricing all over the place...actually, while I'm asking, same question applies to pads, shoes, and whatever else I might need as a sundry item for what will probably be me doing the work (sigh...) Let me know if you've got some solid recommendations.
I drilled down as follows, and nearly certain I've got RWAL only:
DODGE 1997 RAM 3500 PICKUP 5.9L L6 DIESEL Turbocharged Brake/Wheel Hub Rotor
Mahalo - Dave
I'm browsing at Rock, thinking I will prolly order up a worst-case collection of brake parts to minimize the emergency-trips to NAPA, always on a Sunday afternoon, just when they're closing... What's your wisdom about Rock's vast rotor selections? Looks like they're available with or without the snout, many options, and pricing all over the place...actually, while I'm asking, same question applies to pads, shoes, and whatever else I might need as a sundry item for what will probably be me doing the work (sigh...) Let me know if you've got some solid recommendations.
I drilled down as follows, and nearly certain I've got RWAL only:
DODGE 1997 RAM 3500 PICKUP 5.9L L6 DIESEL Turbocharged Brake/Wheel Hub Rotor
Mahalo - Dave
11-13-2015, 08:00 AM
#24
Administrator
LOL, Rock Auto is my savior and I used to own a Federated auto parts store.......... So I am probably not the best guy to ask.
That being said, I try and keep parts ahead, ready to change, so my last set of front pads was a set of Raybestos superstoppers that I paid something like 23 bucks for on closeout.
If it were me, and fair notice, I am a Raybestos guy, I would run red label ( OEM grade ) Raybestos rotors IF needed, and probably something like the Raybestos EHT459H advanced brake pad, for 40.89 I don't think you can go wrong.
FWIW your friend is right about the rotors, unless pulsing or more than a 1/16" groove, it is better to leave them alone. The logic is when you are breaking in the rotor, there is a carbon matrix formed on the surface of the rotor, which provides long life and optimum braking ( not glazed, that is different ). I have almost 200K on Greenie, original rotors and so far as I know, never been cut.
And that price isn't as out of line for a shop today as you might think, brake work isn't cheap......
I would pull my rears apart before I ordered though, both of mine have had 80 percent of the shoes left when the trucks had high 100's of thousands of miles......
I would almost bet your pedal drop issue is the RWAL control valve, do a search there have been several threads regarding it. The same valve runs from 94-99 on at least 1/2 to 1 ton and Vans if I remember right........
Oh yea, check your brake hoses as well, Hawaii might be more gentle on them than Illinois, but eventually they are gonna break.
That being said, I try and keep parts ahead, ready to change, so my last set of front pads was a set of Raybestos superstoppers that I paid something like 23 bucks for on closeout.
If it were me, and fair notice, I am a Raybestos guy, I would run red label ( OEM grade ) Raybestos rotors IF needed, and probably something like the Raybestos EHT459H advanced brake pad, for 40.89 I don't think you can go wrong.
FWIW your friend is right about the rotors, unless pulsing or more than a 1/16" groove, it is better to leave them alone. The logic is when you are breaking in the rotor, there is a carbon matrix formed on the surface of the rotor, which provides long life and optimum braking ( not glazed, that is different ). I have almost 200K on Greenie, original rotors and so far as I know, never been cut.
And that price isn't as out of line for a shop today as you might think, brake work isn't cheap......
I would pull my rears apart before I ordered though, both of mine have had 80 percent of the shoes left when the trucks had high 100's of thousands of miles......
I would almost bet your pedal drop issue is the RWAL control valve, do a search there have been several threads regarding it. The same valve runs from 94-99 on at least 1/2 to 1 ton and Vans if I remember right........
Oh yea, check your brake hoses as well, Hawaii might be more gentle on them than Illinois, but eventually they are gonna break.
11-13-2015, 11:38 PM
#25
Thanks patdaly! Good stuff...my oddball friend must have been on to something about not cutting rotors, though it's also possible he was just a cheap bastard like me. Pretty sure any mention of 'carbon matrix' would have gotten me at least the threat of a wedgie in those days, though.
I've got a '96 FSM only, and cheap bastard that I am, still hope to find an elusive '97 free download, but I agree that it's probably worth getting the CD you mentioned once (Geno's Garage) - though I'd really rather not even have the CD around, vs a download. Is that still the place to go, though?
Anyway, other than the vac-assist vs hydraulic-assist, are there other brake differences between '96 and '97 manuals?
FSM spends a lot of time with diagnostic codes/grounding pin 13 (which I'd have to google all by itself) but I have a vague memory of doing this in the foggy past and not getting anywhere with it, much as I'd like to jump right to the problem electronically... What's been your experience with that process?
What you mentioned as the "RWAL control valve" - is that what Rock calls the "ABS hydraulic unit," shown here?: More Information for RAYBESTOS ABS540213 If indeed I could find one for...what did you say? $20 $50?...in a boneyard, I'd install it just to see if it made a difference. Options for used auto parts are limited here, but there's always ebay, one supposes...
Mahalo - Dave
I've got a '96 FSM only, and cheap bastard that I am, still hope to find an elusive '97 free download, but I agree that it's probably worth getting the CD you mentioned once (Geno's Garage) - though I'd really rather not even have the CD around, vs a download. Is that still the place to go, though?
Anyway, other than the vac-assist vs hydraulic-assist, are there other brake differences between '96 and '97 manuals?
FSM spends a lot of time with diagnostic codes/grounding pin 13 (which I'd have to google all by itself) but I have a vague memory of doing this in the foggy past and not getting anywhere with it, much as I'd like to jump right to the problem electronically... What's been your experience with that process?
What you mentioned as the "RWAL control valve" - is that what Rock calls the "ABS hydraulic unit," shown here?: More Information for RAYBESTOS ABS540213 If indeed I could find one for...what did you say? $20 $50?...in a boneyard, I'd install it just to see if it made a difference. Options for used auto parts are limited here, but there's always ebay, one supposes...
Mahalo - Dave
11-14-2015, 03:32 PM
#26
Administrator
Nope, that is for the 4WABS, the 2 WABS looks like this.
It is under the MC and connected to the combination valve.
Anyway, lots of Dodge products from 94-99 used the same thing, so they should be plentiful in the boneyard.
It is under the MC and connected to the combination valve.
Anyway, lots of Dodge products from 94-99 used the same thing, so they should be plentiful in the boneyard.
11-18-2015, 04:49 PM
#27
Patdaly - I am finding some call that a proportioning valve - maybe $50 online or so. Thinking about the 'Junkyard Experience,' the usual local price-gouging, the Dengue fever aspects all make me want to just shell out for a new one, if it's gonna make a difference.
Can diagnostic codes (flashing lights) or some other method narrow this down so I don't replace it needlessly, and then find that it's really my hydraulic reservoir or something else? (Truck did and maybe still does occasionally lose all "power" in braking, leaving me to stand on 'em in a panic, though that hasn't happened recently)
Thanks - Dave
Can diagnostic codes (flashing lights) or some other method narrow this down so I don't replace it needlessly, and then find that it's really my hydraulic reservoir or something else? (Truck did and maybe still does occasionally lose all "power" in braking, leaving me to stand on 'em in a panic, though that hasn't happened recently)
Thanks - Dave
11-19-2015, 08:33 AM
#28
Administrator
Mine never did throw any codes, but I assume that was because I must have had grit or something holding the needle off the seat.
Essentially that thing works like a pressure tank for your well. The reservoir is essentially a bladder that is under pressure but empty, and in normal operation is shut off. When the rear diff thinks it is locking up, the needle comes off the seat to bleed off a bit of the rear brake fluid, and thus pressure until it doesn't see the lockup condition. That is a very quick and dirty description of operation, it isn't technically perfect, but it explains how a bit of grit or dirt in the seat could make you suddenly have no brakes, or what feels like no brakes one time, and perfect ones the next.
Essentially that thing works like a pressure tank for your well. The reservoir is essentially a bladder that is under pressure but empty, and in normal operation is shut off. When the rear diff thinks it is locking up, the needle comes off the seat to bleed off a bit of the rear brake fluid, and thus pressure until it doesn't see the lockup condition. That is a very quick and dirty description of operation, it isn't technically perfect, but it explains how a bit of grit or dirt in the seat could make you suddenly have no brakes, or what feels like no brakes one time, and perfect ones the next.
11-19-2015, 12:16 PM
#29
Mine never did throw any codes, but I assume that was because I must have had grit or something holding the needle off the seat.
Essentially that thing works like a pressure tank for your well. The reservoir is essentially a bladder that is under pressure but empty, and in normal operation is shut off. When the rear diff thinks it is locking up, the needle comes off the seat to bleed off a bit of the rear brake fluid, and thus pressure until it doesn't see the lockup condition. That is a very quick and dirty description of operation, it isn't technically perfect, but it explains how a bit of grit or dirt in the seat could make you suddenly have no brakes, or what feels like no brakes one time, and perfect ones the next.
Essentially that thing works like a pressure tank for your well. The reservoir is essentially a bladder that is under pressure but empty, and in normal operation is shut off. When the rear diff thinks it is locking up, the needle comes off the seat to bleed off a bit of the rear brake fluid, and thus pressure until it doesn't see the lockup condition. That is a very quick and dirty description of operation, it isn't technically perfect, but it explains how a bit of grit or dirt in the seat could make you suddenly have no brakes, or what feels like no brakes one time, and perfect ones the next.
Looking online, I think I priced the hydroboost unit rebuilt at about $160. (A1 Cardone 52-7355 3500 Brake Booster) but of course don't know that it's what I need...
11-20-2015, 08:29 AM
#30
Administrator
That description sounds reasonable but now I'm again confused as to the part/s that's under suspicion. The "under the master" part (proportioning valve), shown shown in the drawing you posted (ID = "RWAL Valve") is not where the accumulator is - that'd be "behind" the master. called the "hydroboost" or some such? Photo of mine: https://www.flickr.com/gp/99860246@N03/962Lyj Maybe you're just meaning to say that the proportioning-valve is likely where the problem is, though it's handling 'output' from the hydroboost/accumulator?
Looking online, I think I priced the hydroboost unit rebuilt at about $160. (A1 Cardone 52-7355 3500 Brake Booster) but of course don't know that it's what I need...
Looking online, I think I priced the hydroboost unit rebuilt at about $160. (A1 Cardone 52-7355 3500 Brake Booster) but of course don't know that it's what I need...
I have never found it aftermarket, Ma Chrysler used to have remanned ones, but the price wasn't pretty.
Part number is R2007312 ( Original part number was 52007312 )