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CptBill · 04-10-2022, 09:06 AM

Started out on our first trip SAt. everything seemed to going along great, got the car on the dolly no problem but on our 3dr stop to make sure the hold down straps were tight we had a problem. Pulled into the rest area did the rest area thing, checked the straps, got back in the MH started it and the brake peddle went to the floor (it was working fine up to that point) pumped it a couple times and still no peddle. got out and looked underneath and there's brake fluid running out of the area where the master cyl. hydro boost is located. had it toed to a shop and am waiting to here. seems odd to me that I can go from normal P32 brake to no brakes at all after stopping

HarryStone · 04-10-2022, 09:12 AM

Sudden failures happen a lot. Be glad it didn't fail while you were driving.

CptBill · 04-10-2022, 09:46 AM

That I'm very grateful for, I can only imagen what might have happed in the VA. or WVA. hills

EyezOpen · 04-14-2022, 09:59 AM

It's all about perception, you just won the lottery would be my thoughts. And then there is the Gaurdian Angel theory...you may wish to lookup and smile...Aside from that good luck with your repairs your on a roll here.

153stars · 04-14-2022, 11:10 PM

Hope you get it straightened as painless as possible.
Twice I blew a brake line hooked up to TT right in front of house with two different trucks. One I was mashing brake because of interlock to shift out park was acting up. Thanked my guardian angle both times and had fixed in hour or so . Be a lot worse on or out on the road.

Isaac-1 · 04-16-2022, 07:13 AM

Sounds like a master cylinder failure, I had one on a car about 20 years ago, I was driving home from work one night when I was almost to the house, I had to stop at a red light, and noticed the brake pedal felt a little odd, a block or so later there was a stop sign where the street crossed a federal highway, I hit the brakes and the pedal went to the floor with no effect, and I blew through the stop sign and across the highway, thankfully there was no other traffic coming. I carefully drove it the last few hundred feet to the house using the emergency hand brake to stop.

D Gardiner · 04-16-2022, 10:49 AM

Quote:

Originally Posted by CptBill

Started out on our first trip SAt. everything seemed to going along great, got the car on the dolly no problem but on our 3dr stop to make sure the hold down straps were tight we had a problem. Pulled into the rest area did the rest area thing, checked the straps, got back in the MH started it and the brake peddle went to the floor (it was working fine up to that point) pumped it a couple times and still no peddle. got out and looked underneath and there's brake fluid running out of the area where the master cyl. hydro boost is located. had it toed to a shop and am waiting to here. seems odd to me that I can go from normal P32 brake to no brakes at all after stopping

Very happy to hear your master cylinder failed while parked. It could have failed at a less opportune time.

RV brakes take a beating, from high heat under braking, long periods of non-use resulting in moisture accumulation and corrosion. Couple that with degradation of rubber components, and lack of brake fluid flushing you get failures.

Noting your RV is about 18 years old, I would replace the master, have the metal lines inspected for rust, replace all of the rubber brake hoses, and either rebuild or replace the calipers.
Did this on our P32 in 2018, and it made a huge difference in its ability to stop quickly.

Isaac-1 · 04-16-2022, 05:38 PM

Mine turned 20 a few months ago, and I am in the process of doing the same, it received new calipers, pads and rubber hoses at the rear last spring, and redoing the front end components, possibly including the master cylinder and hydro boost are on the to do list before our next big trip which will likely be this fall or next spring as we bought a new to us house a couple of months ago and the remodel and then the move will be taking a lot of our time the next few months.

1972VWbus · 04-17-2022, 08:33 PM

Usually one will get a warning if they pay close attention to the pedal. If the pedal slowly drops while stopped. That is the warning. It's dropping due to brake fluid leaking past the inner master cylinder bore (worn seal/s).

I did this job back in 2016 new master cylinder, front rotor hubs, ceramic pads (Centric). I pulled the rear drums and gave everything a good one over. Rear linings were still ~90-95 percent. Buttoned them back up.

Also some (many) of the older P32 chassis do not have auto rear brake adjusters. They adjust while backing up then braking. How often do you spend backing up in your RV say vs your car?

CptBill · 05-03-2022, 01:31 PM

Here's the up date. after going over the brake system with a fine tooth comb we ruled out the master cylinder, booster, Calipers, abs system and decided to replace all 5 rubber brake hoses then flush the system. I picked it up today and put about 150 miles on it with no issues, also included some stops to simulate rest areas. The brake system feels great, good strong peddle no fade and had no issues so we'll see what happens but it appears to be fixed. Thanks for all the suggestion's

LETMGROW · 05-03-2022, 02:12 PM

Quote:

Originally Posted by CptBill

Here's the up date. after going over the brake system with a fine tooth comb we ruled out the master cylinder, booster, Calipers, abs system and decided to replace all 5 rubber brake hoses then flush the system. I picked it up today and put about 150 miles on it with no issues, also included some stops to simulate rest areas. The brake system feels great, good strong peddle no fade and had no issues so we'll see what happens but it appears to be fixed. Thanks for all the suggestion's

Something is wrong here. In your original post you said there was brake fluid running out under your coach yet now you say no leak was found. Was the fluid level low in the master cylinder before you started replacing the hoses?
I go along with the brake fluid change. Condensation can build up in a caliper, water will boil and the bubbles will compress causing a loss of pedal. A caliper piston doesn't have to stick much to cause the brake pads to drag against the rotor and cause heat. Each caliper on your coach had four pistons. This just adds to the odds you could have one sticking out of sixteen.
If I was you I'd invest in an Infrared heat gun and keep a check of all four rotor temperatures stopping frequently to check. If you see one rotor hotter than the other three I'd be looking into replacing the caliper or checking for the slide areas to be sure they are clean and lubed and the caliper is allowed to float.
After having an issue myself I carry a new (rebuilt) caliper with me along with all the necessary tools to change it. Semi annual fluid changes are the normal for me now. Four years ago I replaced all four calipers and added all new pads to my coach.

CptBill · 05-04-2022, 03:48 AM

Just for clarity, 2 pistons per caliper and yes the fluid leak is still a mystery. There where some indications that the left rear brake rotor had been hotter than the rest but all calipers where taken off and bench tested all where free. After eliminating everything else the thought was that at lest 1 brake line was causing a restriction and given the fact that no records where available we could only assume that the fluid in the system was original(18 years old) and thus had at lest sum contamination. We will see but for now all seems to be working as designed after the fix

LETMGROW · 05-04-2022, 12:32 PM

My mistake on the calipers. I just recently replaced the calipers on my '67 Firebird and they are 4 piston calipers. That was a job! One year only design for this car and had to make the lines from the brake hose supports to the calipers. 3" long line with 3 bends in each line.
One line was nearly completed and I kinked it. That line went flying out the back window of my garage and I haven't found it yet. I'll probably find it in a tire on my coach this summer right where I park it. UGH!

92LandYacht · 05-09-2022, 11:56 AM

I find this a little strange as well. Bad hoses alone wont cause the peddle to go to the floor but have no fluid loss. A bad front rubber hose can seem to have fluid coming from above depending on where it was squirting to. Diagnosing where the problem was should have been very easy. Hope they didn't trump up the charges with diagnosis fees.

Replacing all 5 of the rubber lines was a good idea. Had to do the same with my MH a couple of years ago. My symptoms were a little different though. One front wheel was locked up and the fluid would not return to the master cylinder. Decided to replace the front rotors, calipers and pads at the same time I replaced the hoses. This year I decided to replace the rear calipers, rotors, pads and seals. Interesting job since the axles have to be removed in order to get the rotors off.