Master Brake Cylinder

[Monterey_Bay_Cr]

We were on our way home yesterday after a glorious trip to the Grand Canyon, Sedona and Palm Springs. We were in stop and go traffic on 101 for about an hour. Suddenly, my husband said the brakes "went soft". Luckily, he got off the freeway and we sat on the side of a very wide off ramp. We were towed to a parking lot. We called a Good Sam suggested roadside mechanic. He said brake fluid was normal in brake reservoir even tho fluid was dripping from the reservoir. All of this took a couple of hours. After testing the brakes in the parking lot, the mechanic felt we were safe to go to a nearby RV park. We're not sure whether to stay here and wait until tomorrow to have a mechanic look at it or since the brakes seemed fine on our 5 mile trip to the RV park... (were the brakes just hot from the stop and go traffic?) Should we continue on our way home? Our RV is a 1998 Fleetwood Pace Arrow. We only have 23,000 on it.

[tropical36]

Gjac wrote:

tropical36 wrote:

Gjac wrote:

tropical36 wrote:

gutfelt wrote:
worked on lots of brakes over the years never heard of a brake line collapsing internally guess it could happen but rare

Look for it to eventually happen on the front end of an old P32 chassis.
The 97,98 and 99 have different hoses and are hard to find.
The good ones cost money, too.
Best to replace them, ahead of time, instead of waiting for it to happen and maybe lock up and ruin the pad and rotor.
Biggest problem with an internal collapse, is with the fluid not returning to the master cylinder.

If you look at these flexible rubber brake lines for the P-30 chassis you will see the line is attached to the frame through a steel support that surrounds the hose. What happens is the rubber line swells with time and has no place to go because it is surrounded by the steel support tube. The ID gets smaller acting like a check valve. A sign that this is happening is that the MH will pull in the opposite direction of the failing hose when the brakes are applied. This is quite common on the P-30 chassis.

Interesting explanation and never gave much thought to the cause.
Are the earlier models, which are much different, having the same problem?

All the hoses I have seen have been from the 90's, not sure how the earlier ones were supported. I never had this problem with hoses on cars or vans that were just rubber hoses without the metal bracket surrounding the line. Some people report the rubber disintegrates from the inside but I have not see it on my old cars without the metal flange.

If this discussion would have came up at the time of my replacements, I would have sliced it open for an internal inspection. Long gone now, so.........

[Gjac]

tropical36 wrote:

Gjac wrote:

tropical36 wrote:

gutfelt wrote:
worked on lots of brakes over the years never heard of a brake line collapsing internally guess it could happen but rare

Look for it to eventually happen on the front end of an old P32 chassis.
The 97,98 and 99 have different hoses and are hard to find.
The good ones cost money, too.
Best to replace them, ahead of time, instead of waiting for it to happen and maybe lock up and ruin the pad and rotor.
Biggest problem with an internal collapse, is with the fluid not returning to the master cylinder.

If you look at these flexible rubber brake lines for the P-30 chassis you will see the line is attached to the frame through a steel support that surrounds the hose. What happens is the rubber line swells with time and has no place to go because it is surrounded by the steel support tube. The ID gets smaller acting like a check valve. A sign that this is happening is that the MH will pull in the opposite direction of the failing hose when the brakes are applied. This is quite common on the P-30 chassis.

Interesting explanation and never gave much thought to the cause.
Are the earlier models, which are much different, having the same problem?

All the hoses I have seen have been from the 90's, not sure how the earlier ones were supported. I never had this problem with hoses on cars or vans that were just rubber hoses without the metal bracket surrounding the line. Some people report the rubber disintegrates from the inside but I have not see it on my old cars without the metal flange.

[falconbrother]

gutfelt wrote:
well iam certainly not going to sit here and say brakes lines don't fail as alluded to in several posts but I have worked on a lot of brakes in my lifetime and I have never seen or heard of one till this forum;I will say this type of failure is a very low % of any brake failures out there though

As a general rule this is my experience as well, with a couple of exceptions. Some early GM lines that would rust through and the front rubber hoses on the P-30. Mine were replaced when I bought the motorhome because the had created a situation where the pads wouldn't release. But, I don't worry about brake lines on cars and trucks.

[tropical36]

Gjac wrote:

tropical36 wrote:

gutfelt wrote:
worked on lots of brakes over the years never heard of a brake line collapsing internally guess it could happen but rare

Look for it to eventually happen on the front end of an old P32 chassis.
The 97,98 and 99 have different hoses and are hard to find.
The good ones cost money, too.
Best to replace them, ahead of time, instead of waiting for it to happen and maybe lock up and ruin the pad and rotor.
Biggest problem with an internal collapse, is with the fluid not returning to the master cylinder.

If you look at these flexible rubber brake lines for the P-30 chassis you will see the line is attached to the frame through a steel support that surrounds the hose. What happens is the rubber line swells with time and has no place to go because it is surrounded by the steel support tube. The ID gets smaller acting like a check valve. A sign that this is happening is that the MH will pull in the opposite direction of the failing hose when the brakes are applied. This is quite common on the P-30 chassis.

Interesting explanation and never gave much thought to the cause.
Are the earlier models, which are much different, having the same problem?

[Gjac]

tropical36 wrote:

gutfelt wrote:
worked on lots of brakes over the years never heard of a brake line collapsing internally guess it could happen but rare

Look for it to eventually happen on the front end of an old P32 chassis.
The 97,98 and 99 have different hoses and are hard to find.
The good ones cost money, too.
Best to replace them, ahead of time, instead of waiting for it to happen and maybe lock up and ruin the pad and rotor.
Biggest problem with an internal collapse, is with the fluid not returning to the master cylinder.

If you look at these flexible rubber brake lines for the P-30 chassis you will see the line is attached to the frame through a steel support that surrounds the hose. What happens is the rubber line swells with time and has no place to go because it is surrounded by the steel support tube. The ID gets smaller acting like a check valve. A sign that this is happening is that the MH will pull in the opposite direction of the failing hose when the brakes are applied. This is quite common on the P-30 chassis.

[Bird_Freak]

My 04 Pace Arrow used to do the same thing. Mine was caused by the brake caliper dragging and over heating resulting in loss of brake pedal. Let it cool a while and pedal would come back and be fine for rest of trip. had this problem for a few years while waiting for Workhorse recall fix.
Finally just sold rv. before fix was found.

[gutfelt]

well iam certainly not going to sit here and say brakes lines don't fail as alluded to in several posts but I have worked on a lot of brakes in my lifetime and I have never seen or heard of one till this forum;I will say this type of failure is a very low % of any brake failures out there though

[rockhillmanor]

X2

When they replace your masters you REALLY should replace the front brake line hoses at the same time. just saying because they are going to fail down the line too. I thought I was a goner coming off that ramp when mine failed!

Regarding availability for 96-98 models. Mine was on a 1997 Ford V10 450 chassis. I HAD to order OEM brake lines for it. They ordered them and they were there the next morning.

Good luck, glad your and your family were ok and you didn't have an accident. Happy Safe Rv'ing when you get your brakes fixed. :C

[tropical36]

gutfelt wrote:
worked on lots of brakes over the years never heard of a brake line collapsing internally guess it could happen but rare

Look for it to eventually happen on the front end of an old P32 chassis.
The 97,98 and 99 have different hoses and are hard to find.
The good ones cost money, too.
Best to replace them, ahead of time, instead of waiting for it to happen and maybe lock up and ruin the pad and rotor.
Biggest problem with an internal collapse, is with the fluid not returning to the master cylinder.

[gutfelt]

rockhillmanor wrote:

Should we continue on our way home? Our RV is a 1998 Fleetwood Pace Arrow.

IMHO. No.


FRONT BRAKE LINES

I lost my brakes coming off an exit ramp just like you did! Everything checked out ok. Thank god I had an experienced truck mechanic at the repair shop I limped into.

You can NOT tell when the front rubber brake lines go, they will look perfectly fine on the 'outside' no leaks or cracks...BUT....

The rubber deteriorate on the INSIDE. They collapse inside and cuts off the brake fluid. And it can be intermittent but all it takes is that one time that they collapse and you have a serious accident.

He took the front brake lines off and replaced them. Problem solved. It is a 'VERY' common problem on 1996 to 1999. But can happen to any year.

The fact that your 98 MH only has 23,000 miles on it means it has sat parked some where for a long time. Brake lines should have been the first thing you replaced and the second thing that should have been replaced where the master cylinders because of accumulation of rust while sitting.

as one can read I was right about my master cylinder theory
If it was brake lines that shut off the fluid your pedal would be hard
not soft and still have braking power although diminished
worked on lots of brakes over the years never heard of a brake line collapsing internally guess it could happen but rare

[Monterey_Bay_Cr]

We ended up staying two extra nights and met with the mechanic the RV park owner recommended. We were there the first thing this morning. Luckily he was able to fit us in and replace the Master Brake Cylinder. He evaluated the symptoms that I explained and knew what needed to be done. I was keeping in mind all that was posted here and it was very helpful. Thanks again.

[rockhillmanor]

Should we continue on our way home? Our RV is a 1998 Fleetwood Pace Arrow.

IMHO. No.


FRONT BRAKE LINES

I lost my brakes coming off an exit ramp just like you did! Everything checked out ok. Thank god I had an experienced truck mechanic at the repair shop I limped into.

You can NOT tell when the front rubber brake lines go, they will look perfectly fine on the 'outside' no leaks or cracks...BUT....

The rubber deteriorate on the INSIDE. They collapse inside and cuts off the brake fluid. And it can be intermittent but all it takes is that one time that they collapse and you have a serious accident.

He took the front brake lines off and replaced them. Problem solved. It is a 'VERY' common problem on 1996 to 1999. But can happen to any year.

The fact that your 98 MH only has 23,000 miles on it means it has sat parked some where for a long time. Brake lines should have been the first thing you replaced and the second thing that should have been replaced where the master cylinders because of accumulation of rust while sitting.

[gutfelt]

as I said in first post sounds more like master cylinder bypassing
once fluids are boiled and theres air in the system the pedal stays soft till bleed out;; in this case the pedal returned to hard normal
at least what OP indicates

[tropical36]

Monterey Bay Cruzers wrote:
We were on our way home yesterday after a glorious trip to the Grand Canyon, Sedona and Palm Springs. We were in stop and go traffic on 101 for about an hour. Suddenly, my husband said the brakes "went soft". Luckily, he got off the freeway and we sat on the side of a very wide off ramp. We were towed to a parking lot. We called a Good Sam suggested roadside mechanic. He said brake fluid was normal in brake reservoir even tho fluid was dripping from the reservoir. All of this took a couple of hours. After testing the brakes in the parking lot, the mechanic felt we were safe to go to a nearby RV park. We're not sure whether to stay here and wait until tomorrow to have a mechanic look at it or since the brakes seemed fine on our 5 mile trip to the RV park... (were the brakes just hot from the stop and go traffic?) Should we continue on our way home? Our RV is a 1998 Fleetwood Pace Arrow. We only have 23,000 on it.

Sounds like you boiled the brake fluid.
This usually happens with improperly descending a steep grade.
It can also happen with driving in heavy traffic, if the brake lines are close to the exhaust manifold.
The immediate cure is to flush and replace the fluid and do so again in two or three years.
New fluid has a boiling point of 400F +, but with time, it collects moister and yours most likely will now boil at 212F.
On our old gas coach, I put a piece of alum. between the brake lines and the exhaust manifold to better direct the air flow and for blocking the heat, somewhat.