Unusual Brake Situation

[gmfryer]

Have a '99 Coach which I have had for 6+ years now. Had the front brakes re-done last year because they were sticking and overheating from time to time and I could smell them periodically.

I was coming into the campground in MO and had to climb a pretty good grade to get in, a least 10%. I pulled up to register, got back, cranked it up and continued on to the site and the next time I applied the brakes the pedal went almost to the floor, I pumped the brake pedal a few times and the pedal returned to normal pressure. I pulled into my site and parked and after getting settled I noticed a very small wet stain on the pavement under the brake reservoir. I checked the level in the reservoir and all is fine. I have been here for a few weeks and occasionally depress the brake pedal, without the engine running and all seems OK.

Anyone ever experience this before? I would appreciate any comments.

Greg

[Algoma]

When you depress the brake pedal without the engine running do you hear and feel the Hydromax backup motor running? This should come on automatically when you have no hydraulic pressure from the engine, even with the ignition off. The leak may be from the Hydromax under your feet, not the reservoir.

[EngineerMike]

Could the incline been steep enough to allow the master cylinder to have sucked air?

[Dave Fernandez]

Hello Greg:

Sorry about the problems with the brakes.I am going to throw in my $0.02 of a possible problem. If you have a fluid leak find where it is coming from and repair it. If no leak is found you may have an internal leak on the brake master cylinder. Since it is a sealed system the only way to introduce air into the brake system is a fluid leak and the brake fluid reservoir runs out of fluid and air enters the system or you open the system and introduce air into the system.

No normal angle a vehicle is place into will introduce air into the system unless it is so sever that the rubber side is no longer down. I have taken my Jeep and done some sever Rock Climbing and have even laid on it side and have never introduced air into the brake system.

If the internal seals on a brake master cylinder are going bad, they can cause the master cylinder to temporally loose internal pressure. As you press on the pedal the fluid bypasses the internal rubber seals and pedal will go to the floor. Once you pump the pedal the pressure should return to normal. This in the past was a sign that the master cylinder was starting to go bad.

This symptom may happen once in great while at the start and progressively get worse and happen more often.

[Flagelpater]

FWIW I agree with Dave Fernandez for the most part. First, are you sure it is your fluid that was on the ground? Could it have been from another vehicle? Bad seals in a Master Cylinder should Not dump fluid on the ground. If it is your fluid you should see evidence somewhere on your chassis.

[wa8yxm]

The wet spot under the brake master cylinder may have been from your vehicle, but from another source.. There is, often, a drain hose near that same location that does, normally, drip nothing more frightening than water, and distilled water at that (Though it may have contaminates in it picked up from where it condensed to where it dripped out)

[gmfryer]

Yes, I can hear the Hydromax backup motor run when I depress the break pedal. The fluid definitely came from the reservoir area because the "wet spot" was just under the front left side of the coach. There is no sign of a leak now as I sit here, plus the reservoir wasn't/isn't low on fluid.

I have looked carefully and see no leaks around the brake master cylinder. What I did notice was a leak from safety steer stabilizer, any recommendation for a replacement?

Thanks for the assistance.

Greg

[Flagelpater]

FWIW Don't forget, you said your brake peddle went to the floor. Something else also needs your attention.

[gmfryer]

Not sure if it went to the floor exactly but it went much further than normal and that is when I pumped the pedal.

[Algoma]

When you had your front brakes re-done did they flush the brake fluid out completely and replace with new? If they only topped up and bled the front front brakes maybe you have some air in the system that caused your pedal to sink.

[Pigman]

It sounds like you might have boiled the brake fluid. If the brakes had been used and then sat a few minutes, residual heat could have boiled the fluid. Since brake fluid attracts moisture in the air, if it hasn't been replaced in a long while it could have bubbled enough to give you a soft pedal and push some back out the master cylinder. My first try would be to do a complete flush.

John

[gmfryer]

Yes, the fluid was replaced last year and the system bled when the front brakes were replaced.

That boiled theory sounded good but the fluid is synthetic and only one year old so it probably wasn't it.

Thanks for all the ideas everyone.

Greg

[wa8yxm]

Quote:

Originally Posted by gmfryer Yes, I can hear the Hydromax backup motor run when I depress the break pedal. The fluid definitely came from the reservoir area because the "wet spot" was just under the front left side of the coach. There is no sign of a leak now as I sit here, plus the reservoir wasn't/isn't low on fluid. I have looked carefully and see no leaks around the brake master cylinder. What I did notice was a leak from safety steer stabilizer, any recommendation for a replacement? Thanks for the assistance. Greg

Glad you found your leak, and again I say it may have come from "Above" as there may be a normal drain hose near there.

However, since you ask.. I kind of like the Blue Ox True Center that is currently resting comfortably in Pender NE (I'm in Michigan) where it should be fixed and returned to me ... Shortly... I hope. (There are two or 3 versions of the True Center, The current version is "Revision 3" as they say.. (Don't buy anything till Revision 3) Alas, I got a Revision 2.... So, thank heaven for Warranties)