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captainkf
New Member
Canada
9 Posts |
 Posted - 10/04/2007 : 9:10:52 PM
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Hello all, New to the forum. I have an 85 gmc c60 56pax bluebird bus. I had a bunch of brake work done last year and then the bus sat (near the ocean for a bit) then drove across canada, then to bc in the winter. I washed off as much as possible off the wheels then let the bus sit for 5 months. When I went to move it I noticed the brake resevoir cap missing. Everything looked ok, but I learned later that my rear brakes and front passenger (rear drum, front disc) brakes were not engaging. The fluid is topped up though. So, is it possible that moisture or air in the lines may be causing this? Can it be sorted with bleeding? I've never bled the lines on this vehicle, how difficult is it? Or could it be that calipers are siezed? Or more that I don't know about?
If it is more than just a bleeding issue, how much is this going to end up costing? Any thoughts?
Thanks, I look forward to hearing from you.
-Richard |
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Brad Barker
Administrator
USA
874 Posts |
Posted - 10/07/2007 : 8:12:19 PM
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| Did you run the buses after washing them off? If not the brakes might have rusted in place. I make it a practice to always make sure my brakes are warmed up before parking even overnight. This dries them out to prevent rust from forming. Moisture could have gotten into the system especially if the reservoir cap is missing. I recommend pulling the wheels and doing a visual on the hardware first. Make sure drums are in place and tight if you pulled them for inspection prior to bleeding. If you have a power bleeder start bleeding at the wheel that is farthest from the reservoir first. If you do not have a power bleeder it will take a while doing it manually. You will need someone to help you with a strong leg. A lot of pumping of the brake pedal is needed. With the engine off, pump the brake pedal until a firm pedal is felt, hold pressure on it, then open the bleeder screw at the wheel farthest from the reservoir. When the pedal stops descending hold it there until the bleeder screw can be closed. Repeat the process several times for each wheel. Holding light pressure over the bleeder screw oriface will tell you when air escapes. Wear safety glasses and keep the reservoir full at all times. If the pumper lets up on the pedal before you close the screw air will be sucked into the system and you will have to start all over again. If this does not remedy the problem you may have to disassemble components. If you are getting good clean fluid at all four wheels and the brakes still do not apply then the calipers and wheel cylinders or shoes may be seized. |
Brad A. Barker |
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captainkf
New Member
Canada
9 Posts |
Posted - 10/08/2007 : 09:28:44 AM
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Thanks Brad, I really appreciate the step by step advice. Do you have a recomendation for a power bleeder? Does it have to be extra large for commercial vehicles? I live in a small community so I will look into getting something shipped.
-Richard |
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Brad Barker
Administrator
USA
874 Posts |
Posted - 10/08/2007 : 11:37:09 AM
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| Mine is a bleeder ball from Wagner Brake Corp. It hold about a gallon of fluid and has several attachments for different types of reservoirs. Easy to use. There are several brands out on the market. I do not have a model or part number. |
Brad A. Barker |
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captainkf
New Member
Canada
9 Posts |
Posted - 10/09/2007 : 08:46:58 AM
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Thanks for your help.
-Richard |
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thomasguy
Active Member
Canada
21 Posts |
Posted - 10/09/2007 : 11:05:18 AM
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Hi Richard,
I agree with Brad, a power bleeder is the best way to go but you can get by bleeding the system with help. If you're brake system is a hydra-boost model then you have the power assist from the emergency electric motor [works anytime since it has a direct 12V feed]
We've had caliper problems even without high moisture, the high heat effects them as well. Removing wheels should be done without question and shouldn't take more than a day [depends who's doing the work] you may need wheel seals and depending on shop rate and what is found once the brakes are exposed, no one can tell you until you reach that point.
Just from experience and working at a GM dealer I always replaced wheel cylinders without question. Hydraulic brakes are extremely unpredictable so the extra cost is well worth it.
You had a complete brake job done already so you shouldn't have to replace a lot of parts, just a good lube on the mechanical end.
here's a link I found on Google for some bleeders
http://www.nextag.com/pressure-brake-bleeder/search-html
John |
School Bus Maintenance & Repairs.
http://schoolbusmechanic.blogspot.com |
Edited by - thomasguy on 10/09/2007 12:10:03 PM |
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captainkf
New Member
Canada
9 Posts |
Posted - 10/10/2007 : 8:40:48 PM
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When I took it to a local shop they said they were going to use replacement units that replaced the whole brake assembly. Does anyone have info on this? When I take off the wheels, should I be able to see the drums activate when the brake pedal is depressed? I assume they are just a larger version than I would find on a "regular" car. Are wheel seals pricey? If bleeding does not do the trick, should I buy caliper's for the front? What do I get for the drums? I know these may seem like obvious questions, but I just want to know what I am getting into before I start. I can't just drop into a garage because the bus is unisured. So I get to do all the mechanical, yay:)
-Richard |
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baptistbusman
Advanced Member
USA
301 Posts |
Posted - 10/11/2007 : 08:37:06 AM
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when you said the brakes are not engaging, does the pedal basically go all the way to the floor with no pressure at all?
Yes, you can see the wheel cylinders activate with the pedal depressed. However you will probably have to remove the brake drum to see them, unless you can see inside from the back.
Wheel seals are usually around $40 apiece. If your careful, you can get by without replacing them. The actual axel seals, the ones that go on the front, are really cheap, or you can just use some rtv to seal them up.
Is there any fluid in the system at all? I think you should probably start there. open up the bleaders on the rear first, and pump the thing empty. Then refill and bleed again.
A power bleeder is awesome, but if nothing else, get some clear tubing that will fit over the bleeder screw end and put the other end in a containter of brake fluid. That when when you pump the brake, it pumps the air out into the container and pull fluid back up into the lines.
I think though, that a good flushing of the lines and a refill and bleed is the best place to start. It will either fix the problem, or reveal a leak somewhere. |
1 Timothy 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief. |
Edited by - baptistbusman on 10/11/2007 08:39:07 AM |
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misterbill
Advanced Member
United States
306 Posts |
Posted - 10/12/2007 : 07:28:18 AM
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| I would never buy a power bleeder. I probably have to bleed brakes once every five years. Not worth it to me(although I have never priced one). I bled the brakes on my dumptruck a few weeks ago without any help. I replaced my wife with a stick between the seat and the brake pedal. She didn't seem to mind. |
High School Friend-"Hey! How are you! Well, I guess you can't be doing too well, you're driving a school bus." |
Edited by - misterbill on 10/12/2007 07:30:02 AM |
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raytobe
Advanced Member
USA
293 Posts |
Posted - 10/12/2007 : 5:37:27 PM
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| Power bleeders are great addition to the old toolbox imho. Makes flushing the hydraulics a breeze. Not just good for bleeding. The brake fluid in a hydraulic system should be changed on a regular basis, just like changing the oil just not as often. |
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captainkf
New Member
Canada
9 Posts |
Posted - 10/12/2007 : 6:22:11 PM
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Again, thanks so much for all the help! I might take a crack at it next week. We'll see how much I'm working.
The brake pedal does not go to the floor and the front brake(s) are engaging.
I think I will be passing on the power bleeder as they are a bit pricey.
-Richard |
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IBTMech
Top Member
USA
973 Posts |
Posted - 10/13/2007 : 3:31:36 PM
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I have been using a vacuum bleeder in recent years. My old pressure bleeder has been sitting in the corner for 4-5 years now.
Except for the police cruisers, rescue units and public works pickups, everything is air brakes nowdays........ real easy to bleed............ |
If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years. |
Edited by - IBTMech on 10/13/2007 3:32:42 PM |
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misterbill
Advanced Member
United States
306 Posts |
Posted - 10/14/2007 : 04:39:33 AM
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quote:
Originally posted by IBTMech
Except for the police cruisers, rescue units and public works pickups, everything is air brakes nowdays........ real easy to bleed............
Yes, but nearly impossible to get all of the air out of the brake lines. |
High School Friend-"Hey! How are you! Well, I guess you can't be doing too well, you're driving a school bus." |
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captainkf
New Member
Canada
9 Posts |
Posted - 10/17/2007 : 09:03:46 AM
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hey ibtmech, wanna sell it cheap? :)
-Richard |
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Topic |
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brakes not engaging
