Help!! I can't stop stopping

[phillbus914]

I took my bus for a spin yesterday to sotra test drive it before my 3,500 mile trip to South Padre Island next month & I have a problem...

When I use the brakes the brake pedal doesn't fully return. Basically it keeps stopping after you let off the brakes. You have to pull the pedal up with your foot to let off the brakes.

Some info on my bus

Has hydraulic brakes, and some electric motor runs when you turn the key on, the motor changes pitch when you step on the brakes.

The bus has not been driven in about 3 months; last time it was driven there was no problem with the brakes.

My bus is a 91 Blue Bird TC2000 with a front mounted 5.9Cummings turbo diesel engine & an Allison 545 auto Transmission.

I don't think it's a stuck caliper or & a pinched line or anything like that since the brakes release when you pull up on the pedal. If it were a stuck caliper I would think this would make no difference. There is no dragging once the pedal is pulled back to its off� position.

I also checked the master cylinder & found that the fluid was dirty and a little low, maybe 1/3 inch low on fluid. I bought a big can of fluid & a turkey baster & sucked out as much fluid as possible and refilled it to the full line. Test-drove it.... problem was still there.

I crawled under the front of the bus (where the brake pedal linkage is) and had a friend pump the brake pedal while I squirted every pivot point with liquid wrench..... Problem was still there.

I'm thinking maybe it's a problem with that electric motor. Anyone have these on their buses? Does anyone know what its called? Are the hard to replace, if need be?

I stopped at a bus/motor home repair garage & the guy said it acts like a failsafe, if your brakes go out it will somehow allow you to stop. I would have left it there but it's $80 to have them look at it.

Any Ideas?

[hoser]

Think the cold weather has anything to do with it?

Water in the fluid is frozen?

Can you bleed the system?

[Griff]

Originally Posted by macgyver

Try bleeding your brakes... get some fresh fluid into those lines. Old fluid is bad...

Always start with the wheel furthest from the master cyl and work your way closer. Be careful not to suck air back into the lines again or you have to start all over again... (Been there, done that... It SUCKS)

Good luck.

-Mac

Words of wisdom to be sure!
While it wasn't a school bus (it was a 1986 Pontiac Parisienne Safari station wagon), it had electro-hydraulic brakes just like you are describing. I experienced a similar problem with it that indeed turned out to be the electromotor. A new one would had to have been special ordered for just over $300.00 (back in 1996) and was not affordable to me.
The solution was to go to a scrap yard and take a power brake booster system off a junked vehicle (of similar model) and replace my electro-hydraulic system. I got the booster, master cylinder, master cylinder plunger shaft & brake pedal (my old brake pedal & shaft were not compatible with the booster system) and the vacuum line that goes from the engine to the booster all for $75.00. It only took about 4 hours to complete including removing the parts from the scrap yard vehicle and my vehicle, rebuilding the master cylinder, and installing the works in my vehicle. Worked like a champ (until the engine blew 2 years later). I also used the one-man brake bleeding kit I got from JC Whitney years ago and performed the sequence Macgyver correctly posted.
If someone is knowledgeable on this system on a bus, perhaps you could recommend a suitable "donor" vehicle he could convert his system to.

[phillbus914]

I will try to bleed the system before the trip to Texas, but it was freezing rain & Hailing out today, hopefully the weather clears up sometime before the trip.

I don’t know if the cold weather has anything to do with it since it wasn’t below freezing yesterday when I drove it.

I also should have mentioned that the brake pedal does come up almost all the way but stops about 1" from the top. It’s like it getting jammed or something, almost like the linkage is binding. In my bus you sit in front of the front wheels so there is a lot of linkage from the brake pedal back to the master cylinder. Actually the master cylinder is accessible from inside the bus, it sits under the drivers seat.

[phillbus914]

Yes I can pull the pedal up with my foot when taking off from a stop. Once the pedal is up its fine... untill the next stop.

[Steve]

Put a new spring on that thing!

[lapeer20m]

Properly working brakes are overrated!

She might not stop, but after tightening the govenor springs she sure does go!


Just kidding about the brakes by the way......brakes on a skoolie are extremely important.

[phillbus914]

Originally Posted by Steve

Put a new spring on that thing!

Any idea where this spring is? I think I could add one on the linkage under the brake pedal since the pedal goes straight down through the floor, and then back under the drivers seat. This sounds like a great idea.... I think I might try that sometime when its not 5* out maybe on the way to Texas next month.

For a min there today I also had a sticky throttle; Jason (lapeer20m) came out today and we adjusted the governor springs which required adjusting the throttle linkage.... during one of the several test drives BOTH the brake pedal and throttle were not returning to rest positions. Luckily we er uhh I mean Jason fixed the throttle problem. Now my bus runs about 64-65mph on flat ground… much better than 57mph, but that’s another post.