Smoking brakes question June 19, 2023, 03:35:33 pm Hi All,Got some questions for ya, looking for advice, thanks in advance. We are on a big 3 week trip out to NC and back to CA. I recently had the brakes serviced; new pads, calipers and rotors turned on all 4. I’m newish to RV driving, bought LD in 2021 (not a total newbie, did a 5000 mile trip all thru the west in 2021 with lots of mountainous miles put in). We are in NC now, and I drove on the Blue Parkway from Cherokee area down to Rosman area. On the downhill I was not riding my brakes and using the on-off method as well as using 3rd and 2nd gear to help slow the vehicle. At a certain point we started to smell the brakes and they felt less responsive so I pulled over. When I got out we had what seemed to me like quite a lot of smoke coming from the brakes. I waited an hour before descending again. All operated well. 2 questions for you all:1. If I was driving the downhill properly could something have locked up to cause the smoke? Are the brakes more prone to issues having just been redone? I feel like I would have had issues with the brakes my first time out in 2021 driving in the west if I was doing something wrong, not on a short’ish drive on the Blue Ridge Parkway.2. Should I have the brakes looked over now? Any suggestions for a place to go in the Rosman NC area?Thanks my friends!John
Re: Smoking brakes question Reply #1 – June 19, 2023, 05:35:52 pm Hey John,From your description, it sounds like you had a brake seize up, perhaps more than one. I realize you had your brake pads and calipers replaced, and the rotors resurfaced. Seized brakes are usually caused by a sticking caliper. Many years ago, I had a similar problem. As strange as it may sound, my problem turned out to be a brake hose that was not allowing brake fluid to return upon release of the brake pedal. I have no recommendation for a repair shop. I would suggest you buy a non-contact infrared thermometer to carry in your rig. It can be used to check brake and tire temperatures when you stop and a higher temp on one wheel can indicate a sticking caliper. Also useful to indicate a tire that has lost some air. Good luck,Steve K 2 Likes
Re: Smoking brakes question Reply #2 – June 19, 2023, 07:16:57 pm I had an issue with the replaced master cylinder not always releasing completely.Best of luck with your brakes
Re: Smoking brakes question Reply #3 – June 19, 2023, 08:14:25 pm Was smoke coming from all four wheels or only one?It makes a big difference in potential causes.Larry
Re: Smoking brakes question Reply #4 – June 19, 2023, 10:14:23 pm Was the brake fluid changed as part of the recent service? My rig sat for a while before I bought it and I had brake issues off and on until I replaced calipers, rotors, pads, and hoses AND started flushing the brake fluid every other year. I also lube the caliper slide pins whenever I have the front tires off. I've driven my rig through the NC mountains many times, and find it very easy to get heat into the brakes. I've read many times that the front brakes on my e450 (not sure which platform you have) are undersized for heavier rigs on that chasis and I believe it. Rich 1 Likes
Re: Smoking brakes question Reply #5 – June 20, 2023, 10:22:23 am Hi Guys,STEVE: Thank you sir, I was thinking something like that too. The mechanic said I had a sticking right front caliper, so I figured just change them all. I’ve never seen smoke like that on the rig before, but I’ll look into that thermometer. And thanks for the info on that brake hose issue you had.LISA: Thanks for the info Lisa, we didn’t touch the master cylinder this time but I appreciate the additional info.RICH: Yes sir, brake fluid was flushed as part of the job, I should have said that.LARRY: Honestly it was hard to tell. At first it seemed like it was driver side front and rear mostly, but the wind made it tough to determine exactly because at times it would caused the smoke to billow out of the opposite side of the rig. Front hub caps felt hotter than back though.RICH: Yes sir, brake fluid was flushed as part of the job, I should have said that. I appreciate your knowledge of those mountains, I was curious if others had issues there. We had zero issues in the Smoky Mountains Nat Park though, seemed like similar terrain. We do have the e450.
Re: Smoking brakes question Reply #6 – June 20, 2023, 12:25:38 pm Just curious, do you have a Tire Pressure Monitoring System (TPMS) that measures tire temperatures?
Re: Smoking brakes question Reply #7 – June 20, 2023, 12:39:06 pm "I would suggest you buy a non-contact infrared thermometer to carry in your rig."I heartily endorse Steve's idea as an intermediate step in lieu of a TPMS system! Small, simple to use and critical when needed.
Re: Smoking brakes question Reply #8 – June 20, 2023, 01:17:29 pm If more than one brake was smoking, good chance the master cylinder is not fully releasing . The MC and/or the hydraulic booster may need replacing, along with any parts damaged by the overheating. It should be checked out by a brake specialist.Larry 2 Likes
Re: Smoking brakes question Reply #9 – June 20, 2023, 07:57:45 pm Thanks guys,JOEL: I actually do have TPMS system, and it does measure temperature. I forgot about that part until late in the brake smoke incident, but I saw at least one tire that was registering 125F, I wish I had checked it sooner to see just how hot things actually got.LARRY: Thanks, I have dropped her off at a place to get her checked out, hopefully there’s no serious damage or necessary repairs.
Re: Smoking brakes question Reply #10 – June 21, 2023, 07:00:06 am I had this happen....the previous owner had replaced frt brake pads, rotors/hubs and calipers(2004 mb with 60k miles )...i replaced them again because they were grabbing and pulling right. Then my very next trip to the Highlands in N.C. the rear ones.started acting up...i then discovered the old brake lines were collapesings...so i replaced all brake lines with oem...and just pads and rotors in rear. Its another issue with Ford....they only have rebuilt calipers now.for.older units....bleed your brakes every 1 or 2 years.esp if towing. 1 Likes
Re: Smoking brakes question Reply #11 – June 21, 2023, 04:34:58 pm FRANRAM: Thanks for that information, much appreciated, I’ll ask about that with the mechanic. 1 Likes
Re: Smoking brakes question Reply #12 – June 22, 2023, 05:31:52 pm Just an update guys for the thread, mechanic who’s looking at things for me is saying all four wheels are locking up. He also said my brake pedal doesn’t feel right, sounds like it doesn’t go down far enough in relation to how much the brake is being applied, resists far too early (honestly after my recent brake job I thought the pedal felt weird but I figured it was just me). The mechanic is saying the only thing that could do what he’s seeing is a problem with the ABS module or an issue with the master cylinder (like LARRY said). Thanks for all the help guys, I’ll update the thread when it’s more clear what’s wrong.
Re: Smoking brakes question Reply #13 – June 22, 2023, 07:16:16 pm Not sure why it would happen but it appears the master brake cylinder isn't being released. The MC must be totally released to prevent the brakes from locking up. An adjustment between the brake booster and the MC is used to provide a specified amount of clearance when the pedal is released. With inadequate clearance, the brakes will gradually lock up or stay locked up all the time.Not sure if the problem is in the MC or the brake booster. Troubleshooting online is toughThe video below shows the adjustment, note that while it shows a vacuum booster, the adjustment is the same as with the hydraulic booster used on E450s.https://duckduckgo.com/?q=master+brake+cylinder+adjustent&t=osx&iax=videos&ia=videos&iai=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DWI_CXBJ6J3ELarry
Re: Smoking brakes question Reply #14 – June 23, 2023, 06:15:41 pm Thanks for that info LARRY, much appreciated sir. The mechanic is still looking into everything to see if it’s the master cylinder or the ABS module (he’s thinking it might be the ABS). At this point he’s building some jumper lines to bypass the break lines to help figure things out and tell which part is faulty (I’m no mechanic but that’s what he explained to me). We are stuck until Monday at the earliest. Thankfully we are on the leg of our trip where we are staying with friends out in Rosman NC, so this is probably the best time for this whole issue to happen on our trip. Hopefully it turns out to be the master cylinder, sounds like a quicker fix as tracking down an ABS module from salvage will take a few days. Any of you guys know of a good place to find one if we should need one?
Re: Smoking brakes question Reply #15 – July 01, 2023, 12:58:57 pm Hey LARRY, the mechanic replaced the master cylinder trying to see if the problem was there, brakes still locked up. He believes it’s an issue with the ABS module now, so he’s got one coming in to fix it up. Him being a mechanic I assume adjusting the push rod like you showed me was something he understood to do (he does all the work on ambulances in this area). I assume he’s isolated the issue to the ABS module, but is the push rod depth info something a lot of people wouldn’t be aware of? I’m no mechanic, just trying to get educated on this stuff so I can talk to him intelligently about it. What are your thoughts man? Does ABS module issue seem like something that could cause this problem too? We’ve been stuck in NC for two weeks, and we won’t be out now for another week now. Not too much of a problem as we are staying with friends but this issue has taken longer to fix than I thought it would.
Re: Smoking brakes question Reply #16 – July 02, 2023, 01:54:59 am I have little experience with the E450”s ABS, our has not acted up in 140,000 miles. ABS is usually very dependable as long as the brake fluid is changed regularly.Are the brakes locked all of the time or does come on suddenly or gradually?A shade tree test for too small a clearance is to back the master cylinder two mounting nuts off a few turns to open up the clearance. If that eliminates the problem then adjustment is needed. If not, look elsewhere.I would not rule out a brake booster issue.Larry 1 Likes
Re: Smoking brakes question Reply #17 – July 16, 2023, 10:35:57 am So, was the braking problem solved, and if so, what was the cause?Larry
Re: Smoking brakes question Reply #18 – July 28, 2023, 02:10:10 pm Hi LARRY (and all),Had so much going on since we got out of NC that I haven't had time to post some final info on here to tidy this thread up. Thanks for asking too LARRY, just got on here to post and saw you asked, much appreciated sir.So we got the LD back at the 11th hour on Friday July 7th, looks like the ABS module change fixed the issues. They tested it extensively on hills to see if the brakes locking up issue happened, all was good. I did a marathon drive back to So Cal leaving NC Saturday at noon (had a fridge issue I had to sort out before leaving or we would have left earlier) and arriving home Monday night at 8pm. I've never driven 940 miles in one day before but now I guess I know I can, haha! Got a question for you LARRY (or anyone for that matter), when I got the rig back I felt like the brake pedal had more action in it, going down further than before (I believe I mentioned above how my brake pedal felt harder than usual after a large break job I had done right before we left on our trip to NC) so I thought "ah, ok, this is how it's supposed to feel". However after driving it for some time on the return trip to So Cal the hard break pedal action seemed to return. She braked fine every time I needed her too, and I am no mechanic so I'm not sure I'm feeling anything that really shouldn't be there, but I gotta say the pedal still feels weird in my opinion. I was looking up booster information after you talking about it LARRY and it sure seems like they talk about a "hard brake pedal" being a symptom of an issue with the booster. The mechanic who changed the ABS told me he believes the module got gunked up from stuff in the lines when the previous mechanic flushed the lines. Does anyone think it's possible for the booster to be damaged by something similar? Or for the booster to have just had its day and it finally is giving out? Sounded to me like online the info was that boosters don't go bad that often, but then again seems like ABS modules aren't prone to stop working that often either right LARRY? I feel like we have almost every component of the brake system changed now (haha! gotta laugh at that!) so maybe I should just have the booster looked at/changed? Also, what about the brake lines, should I have those changed too, is that a common thing to do at a certain mileage?Thanks for any ideas you have on this, and sorry it took me so long to re-post on the thread. Getting home later than expected on the trip did a number on my schedule for work and side gigs so I've been fighting to catch up (not to mention having to do a deep clean on the fridge)Thanks all!John 2 Likes
Re: Smoking brakes question Reply #19 – July 30, 2023, 02:12:19 am Post note: had the hydro booster checked out at brakemasters today when we got an oil change; they were curious if it was ok too. They inspected things and said all looked good for the hydro booster.
Re: Smoking brakes question Reply #20 – July 30, 2023, 01:24:53 pm I have used the methods below to test the hydro-boost operation in both our LDs and other HD vehicles.Hydroboost Function TestWith the engine off, apply the brake pedal five or more times with medium force to discharge the accumulator. The pedal feel will harden noticeably. Next, apply the brake pedal with medium force and start the engine. If the booster is working properly, the pedal will drop toward the floor, then slightly push back upward. If the booster passes this test, move on to the accumulator test.However, if there is no change in the pedal position or feel, the booster is not working. Hydroboost Accumulator TestTo test the ability of the system to store a short-term high-pressure charge in the accumulator, start the engine and allow it to idle. Charge the accumulator by turning the steering wheel slowly one time from lock to lock; do not hold the steering at full lock for more than five seconds. Switch the engine off, release the steering wheel, and repeatedly apply the brake pedal with medium force. If the accumulator can hold a charge, the hydro-boost unit will provide several applications — hydro-boost units will provide one or two brake applications.As the accumulator charges on a hydro-boost I system, a slight hissing sound should be audible as fluid rushes through the accumulator-charging orifice. Once the accumulator is charged, switch the engine off and do not apply the brake pedal for one hour. Repeat the brake pedal with medium force at the end of the hour. Once again, a hydro-boost I unit should provide two or three power-assisted applications, and a hydro-boost II unit should provide one or two.If the hydro-boost unit fails these tests, usually there is a leak.Brake Booster: How To Test Vacuum Power Assist And Hydroboost Braking SystemsTo increase the longevity of the hydraulic pump, brake booster and power steering box, I install a filter on the hydro-booster return line, something I have done to almost every vehicle we have owned in the last 4 decades or so.Amazon.com: Raybestos Powertrain Inline Magnetic Automatic Transmission /...Note. The filter MUST be located in the low-pressure return line. If installed on the high-pressure side, the filter will blow up, possibly causing injury. If the engine should stall, you have only one, maybe two brake applications before running out of boost, this means only having one good chance to bring the rig to a stop. Press on the brake pedal and never release it until stopped, the transmission is in Park and the parking brake is set. This is a serious warning not to be taken lightly.You cannot provide enough pedal pressure to stop without the hydro-boost being operational.Larry 5 Likes As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
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