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I was driving down a one lane, gravel mountain road with switchbacks for about 4 miles having to keep my foot on the brake in order to descend slowly. I began to smell a burning similar to the smell of a burning clutch. At the bottom of the mountain, I pushed the brake pedal and it went straight to the floor. There was no longer any resistance. I had to drive the rest of the way on the gravel road using my emergency brake to slow down. Then my brake pedal began to work again. What's wrong with my brakes?

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You overheated your brakes. Were you in low gear going down the hill? You should have been, then the engine helps slow your rig. Also the minute you smelled anything you should have found a place to pull over and let them cool. Your driving a big heavy camper that has brakes made for an itty bitty truck. Better check your fluid before your head out tomorrow. Might be a good idea to stop somewhere and have them check the front pads too. Make sure there's some surface left

Linda S

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GET SOME SEMI-METALLIC FRONT BRAKE SHOES!

Emergency/parking brake uses the same brake-shoes in the rear as when you hit the brake pedal. Sounds like you glazed your front brake pads. Any brake system can overheat and "glaze" but cheap front brake pads made of organic material will do it a lot worse then semi-metallic front pads. If it was mine - I'd make sure I've got semi-metallic pads in front, and also downshift more-often and let the trans hold back the rig a bit instead of just the brakes.

I did the same thing last year in a dual wheel 1 ton F350 Ford dually truck pulling a 10,000 lb. trailer down a long hill. Had 2 problems. #1 it had an auto trans so did not hold back very well in a low gear, and #2 the trailer-brakes stopped working and it over-loaded the OEM Ford brake system. In that sort of situation - you have to pump the backs on and off and NEVER use them steady. In my case, using the parking brake had no effect. I'm surprised your's did since, like I said, it uses the same brakes as your foot pedal does (just less of them). There are only a few vehicles on the road that actually have separate brake-shoes for the parking brake (like my 1998 Dodge Grand Caravan). Your Toyota does not.

I

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You boiled the brake fluid that's why you lost brake pressure. Recommend you have it changed and have a good look at the brake lining. DOT 4 fluid has a higher boiling point than the DOT 3 that is in your system they are compatible so it 's not an issue if there is some old stuff left in the system it's a much improved fluid. DOT 5 does not play well with DOT 3 and 4 and should not be used. I do work in top of Mount Washington and they have a road that goes to the top open to the public more than once I have seen brake rotors glowing bright red from people dragging their brakes on the way down.

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your brake fluids boiled.

brake fluids absorb moisture and their boiling point drops drastically over time.

1. change brake fluid

2. next time you go down a switch back keep the car in D1 or D2 and use the engine to slow the car down.

3. DO NOT use DOT 5, the rubber parts are not compatible

Changing brake fluid:

Mityvac, and Castrol LMA or any good brand dot 3 fluid.

first suction out what you can from the brake reservoir and fill with fresh fluid.

then start at the farthest line (pass rear wheel) and open brake bleeder nipple with a 10mm closed wrench, I like to use a stubby as it allows me to get in to close quarters.

use mityvac to pump out and keep topping off the reservoir.

Else pay Toyota to do a Brake Flush, it is only $80 without a coupon :-)

I do it on my daily driver every 3 years regardless of miles.

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3. DO NOT use DOT 5, the rubber parts are not compatible

However, you can use DOT 5.1

"Since DOT 4 and 5.1 are both glycol-based brake fluids they are compatible with each other, which means they can be readily mixed without harming your brake system. It is important never to mistake DOT 5.1 (glycol-based) with DOT 5 which is silicone-based and should never be mixed with any other DOT fluid."

http://www.epicbleedsolutions.com/resources/faq/difference-between-dot4-and-dot51-brake-fluid/

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A driver has to really abuse their brake system to make brake fluid boil, even if DOT3 with water in it. My Ford F350 had new brakes and DOT4 when it boiled the fluid AND glazed the brakes at the same time. But - in my case, I had no choice. My trailer-brakes failed, I was coming down a steep mountain road, and had an automatic trans that did not work very well at holding the truck back. I was lucky it was 4WD and I was able to get it into 4WD and low-range. Having 4WD gave me hold-back with the front and rear wheels and low-range gave me more hold-back power.

Brake pads and rotors often get 600-800 degrees F but fluid rarely get over 200 degrees F unless you ride the brakes something awful. Even old DOT3 isn't going to vaporize until somewhere around 300 degrees F.

My point being this. The worst problem here was mis-use of the brakes. No argument that new brake fluid can give some added insurance. So will better brake pads and shoes. Nothing is going to make the RV able to sustain steady brake use coming down a mountain for a long period of time.

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Same exact thing happened to me in California last summer. Long, VERY steep Forest Service road. I was in 2nd gear, but still had to ride the brakes. Looking back, yeah, I should have been in 1st. But even then, it was steep enough, and the motorhome heavy enough, that there was no getting around using the brakes. No getting around riding the brakes even, really.

You can mitigate with using the transmission to help slow you down, but some grades are just going to be too much for your rig, and you'll need to ride the brakes or not drive the road in the first place.

So yeah, you could have done it "better", but there's only so much you can do.

I had to do the same thing. E brake, and a lot of pumping. I could get brake pressure to come back temporarily if I pumped a few times.

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A driver has to really abuse their brake system to make brake fluid boil, even if DOT3 with water in it. My Ford F350 had new brakes and DOT4 when it boiled the fluid AND glazed the brakes at the same time. But - in my case, I had no choice. My trailer-brakes failed, I was coming down a steep mountain road, and had an automatic trans that did not work very well at holding the truck back. I was lucky it was 4WD and I was able to get it into 4WD and low-range. Having 4WD gave me hold-back with the front and rear wheels and low-range gave me more hold-back power.

Brake pads and rotors often get 600-800 degrees F but fluid rarely get over 200 degrees F unless you ride the brakes something awful. Even old DOT3 isn't going to vaporize until somewhere around 300 degrees F.

My point being this. The worst problem here was mis-use of the brakes. No argument that new brake fluid can give some added insurance. So will better brake pads and shoes. Nothing is going to make the RV able to sustain steady brake use coming down a mountain for a long period of time.

Guess you have never heard of brake fade it comes from boiling brake fluid.

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A 6000# little motor home that was meant to be a pickup does not have the worlds best brakes they are marginal and they are going to get very hot going down hill unless you gear down and pull over to let them cool.

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I had my clutch boil on me while in a mickey d drive through when I lived in KC, MO in summer with the a/c on.

it was a RX-7,

Maintain your brake fluid.

I had my master cylinder go on me on my Honda, once again due to brake system negligence, it feels the same, you lose braking and pedal goes to the floor.

Yes, any vehicle going down an incline for long period will have brakes overheat, I remember driving back from Mt Fuji in Japan and taking the shore route, that was one long downhill switch back drive.

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Guess you have never heard of brake fade it comes from boiling brake fluid.

Of course I've heard of it. But such terms are not exactly scientific and rely on context. When I say "fade" I am referring to when brake linings overheat and glaze. Then no matter how hard you stomp on the pedal (assuming it is working) the brakes won't work. Seems when you say "fade" you are referring to vapor in the hydraulic system and loss of pedal. We use words to convey meaning, correct? Context has much to do with one person understanding the other. So now - I hope - I've made myself clear. I've driven many a truck over the years that has suffered from no brakes due to glazing (or fading), and also from no pedal due to vapor in the brake lines. I've also had both happen simultaneously.

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Thanks everyone! There's always something new to learn about these rigs. I was in second gear the whole way down. I should have pumped the brakes instead of riding them the whole way down. Took it to a friend of a friend who is a mechanic in Missoula. He changed the brake fluid and now we're all good. Now I need to fix a leaking black tank...ew. here's the latest video of our adventure in The Snail

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My father (40 years as a heavy truck driver) taught me to drive and he had one rule for driving in the mountains: Drive down the hill in a lower gear than you used going up. I have driven 4 different cars with the same 2000 pound pop-up and my Toyota RV down many steep hills including highway 14A going west out of Burgess Junction I drive down that hill in FIRST gear for a reason. Let the engine slow you down. I had to use the brakes sparingly and they NEVER got hot.

I also drove down Pike's Peak and they check brake temp part way down. They can tell you to park and cool your brakes. Every time I have driven the Peak, they are surprised that my brakes are not even warm. Why didn't you go to first gear on the way down?

This is the warning sign near Burgess Junction. We took the Toyhouse down 14A without incident.72_buffalo_image-6.jpg

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My father (40 years as a heavy truck driver) taught me to drive and he had one rule for driving in the mountains: Drive down the hill in a lower gear than you used going up. I have driven 4 different cars with the same 2000 pound pop-up and my Toyota RV down many steep hills including highway 14A going west out of Burgess Junction I drive down that hill in FIRST gear for a reason. Let the engine slow you down. I had to use the brakes sparingly and they NEVER got hot.

I also drove down Pike's Peak and they check brake temp part way down. They can tell you to park and cool your brakes. Every time I have driven the Peak, they are surprised that my brakes are not even warm. Why didn't you go to first gear on the way down?

This is the warning sign near Burgess Junction. We took the Toyhouse down 14A without incident.72_buffalo_image-6.jpg

I went that same route Bob in a Dodge van camper. What a drive. I did have to stop a couple of times to cool the brakes off.

Linda S

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