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johnhicks · 08-09-2016, 09:35 PM

This is shaping up to be a little saga, I hope humorous.

A couple of weeks ago I was heading back from Conroe when I discovered that the brake pedal was going down way too far. I had some braking action but not much.

A month earlier I'd gone to Bryan and I thought I had more-than-normal pedal travel but "drain and refill the brakes" was part of the reason I was going to Conroe.

I was on concrete in Bryan with no leak visible, I was on concrete at KOA Conroe with no leak visible.

I'd asked about 3000 miles ago that the brake fluid level be checked. The shop in Conroe didn't get around to it and told me so. I can only assume the shop in north Georgia didn't get around to it 3000 miles ago but didn't mention it.

We've owned this beast for around 3500 miles. The brake fluid might not have been checked for 10 or 20 years.

So I got back to the CG, slithered under there and checked the fluid level in the reservior. Of which there was none. Stuck my fingers in and they came up dry.

Rubber hoses dry. Line joins dry. Wheel cylinder and discs dry. Gads.

I have hydraulic disc brakes with a Hydromax booster. The docs say that if you have spongy brakes or your pedal goes too far down to bleed the brakes once or twice. I think I've sucked up so much air that I have at least a master-cylinder's worth of air in the lines.

So since I've never done such a thing on this scale I start calling around for "mobile truck service." I have naively thought that my knuckle-busting days were over when I sold the old Bug.

The first call is to my local car mechanic guy Franks's (great!) in Navasota. He doesn't do mobile service but asks "whatcha got?" As I described my problem I obviously got further away from anything he wanted to contend with. So he said "call Lonnie."

I called Lonnie and he knew what I was talking about but said his truck had a blowout that took out some wires so he was out of service for a while.

Next I called a "mobile truck service" in Brenham; they obviously had no idea what I was talking about and declined to deal with it.

Next call was to Brumfield in College Station. He said he was more used to air brakes but understood that I wanted him to bring lots of brake fluid and bleed the brakes. Or help me bleed the brakes, no matter. We made an appointment to call each other Tuesday.

I called on Tuesday; he says "I'm stuck in 'Calina! My wife wanted me to take her to Myrtle Beach for her birthday and we went Delta!"

I am not making this up.

I'm in a small CG outside of Washington, Texas, which is outside of Navasota, Texas, which is outside of BFE, Texas, etc.

I could call the Freightliner shop in Bryan and probably get them down here but it'd probably cost $500 without them even doing anything so I resist.

And I keep thinking "brakes is brakes" and bleeding this beast's brakes is no different than bleeding the VW Bug's brakes, just moreso.

Well anyway, I'll update.

Geocritter · 08-10-2016, 06:22 AM

Does your rig have all disc brakes? Though I'm no expert I've found that disc brakes will often gravity bleed. Start with the brake farthest from the master cylinder (passenger side rear) and open up the bleed valve and wait. It may take awhile but it may well bleed itself via gravity. Next do the other rear caliper, then the passenger side front and finally the drivers side front. You can also purchase a small hand operated vacuum pump that you can use to speed things up. It fits on the open bleeder valve.

BTW if you're planning any trips to mountainous areas replace your DOT 3 brake fluid with severe duty hi-temp DOT 5.1 (not 5.0!). You don't want to deal with brake fade on long downgrades. Chances are you'll have trouble finding it in the Texas flatlands and might have to order it.

While you're bleeding your brakes, good luck with the damned fire ants

!

Steve

Piker · 08-10-2016, 07:15 AM

I believe you have the same brakes as I have. In this case, yes... brakes is brakes. You can bleed them like any other brake you've bled. The only real difference between these and the brakes on most passenger cars and light trucks is that these are hydraulic assist instead of vacuum assist.

I'd be concerned about where the fluid went though... after 20 years, I'm sure ours had the original fluid... it had turned to jelly in the top of the reservoir. But it was not low...

-cheers

johnhicks · 08-10-2016, 11:12 AM

Yes, all disc brakes. I'll probably buy a vacuum thing if I have to do it myself.

Where the fluid went is a mystery. I've never seen any evidence of a leak but for the past year or so I've been parked on gravel. We'll go with DOT 4 or 5.1.

Can fluid leak out of the master cylinder into the Hydromax housing?

johnhicks · 08-10-2016, 02:08 PM

Update:

The guys came out today and bled the brakes; it took three of us. The really skinny guy to squiggle underneath, the other guy to pour fluid in the reservoir and me to push the pedal.

We got a lot of air out of each line and the brake pedal feels fine and doesn't creep down. It's real solid like it used to be.

No one found a leak but I'll sure be checking regularly.

Thanks for the help!

bill06447 · 08-10-2016, 06:15 PM

Disc brakes self adjust by virtue of the pad riding on the rotor, the more the pads wear the further the piston moves and the more fluid behind it. If fluid hasn't been checked since brakes were last done you very well may not have a leak, just all the fluid is filling the space behind the caliper piston instead of waiting in the reservoir.

Geocritter · 08-10-2016, 06:19 PM

Quote:

Originally Posted by bill06447

Disc brakes self adjust by virtue of the pad riding on the rotor, the more the pads wear the further the piston moves and the more fluid behind it. If fluid hasn't been checked since brakes were last done you very well may not have a leak, just all the fluid is filling the space behind the caliper piston instead of waiting in the reservoir.

I agree, however he should have a low fluid sensor in his brake fluid reservoir. Maybe he does and it's not working.

Steve

johnhicks · 08-10-2016, 10:02 PM

I suspect that fluid level may not have been checked for 10+ years. There was a little jelly on the reservoir lids. We put another quart through the system so flushed it out.

There's no low-fluid sensor, just a pressure-differential sensor that may not be actually working.

Tidy Tabby · 08-11-2016, 07:01 AM

If the rubber brake lines are original, there could be a source of your problem. IIRC they are typically good for 5-7 years and should be replaced after that. Like any rubber part they will decay, and especially one under pressure. This is very common for rubber brake lines on motorcycles, although in that case the lines are out in the open and exposed to sun and weather and are more susceptible to degradation.
I chased a bad clutch leak on an old Mazda pickup for years, replacing the master and slave cylinders three times each and constantly refilling and bleeding the system until I finally replaced the one section of rubber line from the firewall to the slave cylinder and that stopped the problem. No signs of a fluid leak, but from talking to a number of different people the inner structure of the line had most likely decayed and was allowing the line to expand like a balloon, not visibly of course but enough to cause cracking in the outer rubber sheath and allowing air into the system. Frustrating to chase but satisfying to finally solve. Then a drunk driver decided to total that truck for me so all my effort was ultimately for naught. Now THAT was frustrating.
Good luck with your brakes.

johnhicks · 08-11-2016, 09:21 AM

Thanks for the hint. I'll be getting the system checked in a shop and replacing the hoses will be part of the process.

bsinmich · 08-18-2016, 03:30 PM

Brake fluid, by nature, attracts and holds moisture. As you build up moisture in the lines you have to go back to science classes. Water boils @ 212F. A gas can be compressed and a liquid can't. The boiling temp of fresh brake fluid is around 400F. after building up a little moisture it can drop much closer to the 212 #. I had it happen on a 3 year old Ford chassis. I was coming down a hill and the brake pedal went to the floor. I went through a red light safely. I pulled into a church parking lot and let the brakes cool down. There is only one advantage to this happening in a MH over a TT. Your clean underwear are close.

Geocritter · 08-18-2016, 10:01 PM

Quote:

Originally Posted by bsinmich

Brake fluid, by nature, attracts and holds moisture. As you build up moisture in the lines you have to go back to science classes. Water boils @ 212F. A gas can be compressed and a liquid can't. The boiling temp of fresh brake fluid is around 400F. after building up a little moisture it can drop much closer to the 212 #. I had it happen on a 3 year old Ford chassis. I was coming down a hill and the brake pedal went to the floor. I went through a red light safely. I pulled into a church parking lot and let the brakes cool down. There is only one advantage to this happening in a MH over a TT. Your clean underwear are close.

It happened to my brother several times in a 20 year old Class C he'd just purchased and drove it into the Sierra's on its maiden journey. He's a non-mechanic and called me in a panic asking whatthehell!!! I told him what was happening and ended up overhauling his entire brake system for him, as well as swapping out his 20 year old DOT 3 for Fresh DOT 5.1

There's nothing like losing your brakes to make you a believer in proper brake maintenance.

Steve

udid · 08-27-2016, 09:50 PM

Hoses in general will last decades. I replaced mine (hoses) on my 72 VW Westy after 36 years and they were still functioning as intended when I replaced them. I just did the hoses, master cylinder, pads, shoes and wheel cylinders on my 94 Southwind. Once the rear drums were opened I expected to find worn out shoes. After 22 years the linings still had 95% lining left and everything looked absolutely fine in the drums. But given I had new parts I said out with the old and in with the new. The front brakes on these RV's take the brunt of braking force especially if one has drums on the rears.

My issue with the brakes was mainly the master cylinder (pedal going slowly towards floor). The o-ring on the piston in the bore was wore out allowing fluid to pass back into the reservoir.

Another possibility of having no fluid with no sign of leakage. Fluid may be making it's way into the booster.

While brake fluid does absorb moisture. That should only happen if exposed to it. Which a sealed & properly functioning brake system should not have.

bsinmich · 08-28-2016, 07:59 AM

Quote:

Originally Posted by udidwht

While brake fluid does absorb moisture. That should only happen if exposed to it. Which a sealed & properly functioning brake system should not have.

This is totally false. A brake system is not a sealed system. If this was true you would never be able to apply your brakes because fluid is pushed from the master cylinder to the wheel cylinders. This is replaced by air that is always entering and leaving the master cylinder. Fluid remaining in disc brake calipers is also re-placed by air as the pads wear. There are ways for the moisture to get into the brake fluid. Check the color of brake fluid after 2-3 years and it will most likely be dark colored. That is what happens whenn moisture gets into the system.
I have been to Seattle and knnow you call it a drought whe you go 3 days with no rain. Your brake fluid is absorbing moisture.