Hydralic Brake alarm

cdemaris · 04-17-2010, 07:50 PM

Bought a 1998 Bluebird 63 passenger bus that I am going to convert. I am preparing to paint but I have a problem with the hydralic brake alarm going off. Shut the vehicle off restart and it stops. The mechanic at the school system I bought it from said the brakes are fine just a bad sensor. I may have been to trusting. Has anyone else had this problem and did it cost much to repair?

jkindt · 04-17-2010, 08:10 PM

What chassis is your Bluebird on? Is it Ford, GM, etc.... I have a Bluebird on a Ford chassis and I just went through the whole brake system so I have a fairly good understanding of Ford's hydraulic system. Hope I can help.

cdemaris · 04-17-2010, 09:22 PM

I don't know I will have to look tomorrow and let you know thanks for the offer.

cdemaris · 04-18-2010, 10:55 AM

In Iowa it is illegal to have the "RV" school bus yellow. I have to store it in a storage lot. I have to drive it back and forth to work on it in my drive way. I am doing a basic paint job with brush, roller to get legal. I am new to all this so I may be doing things the wrong way.

Here are some pics of my brake system. One is looking down over the front wheel.

The alarm is going off constantly now as I drive but not at idle. The chassis is International? The manufacturers label is covered in grime and I can't read it. The fluids seem to be OK and I can't see any leeks. The Mech did say it was a bad sensor. The brakes work fine and I don't detect any mushyness or lack of response.

jkindt · 04-18-2010, 11:08 AM

Quote:

Originally Posted by cdemaris

In Iowa it is illegal to have the "RV" school bus yellow. I have to store it in a storage lot. I have to drive it back and forth to work on it in my drive way. I am doing a basic paint job with brush, roller to get legal. I am new to all this so I may be doing things the wrong way.

I wouldn't call it the wrong way. There is no right way.

I don't blame you for painting first, I got my bus and the first priority became paint. Not that it is illegal to leave it here in Alberta, but I want the paint to help dispell the stigma that occurs with school bus conversions. I have found that more and more people are becoming accepting of conversions than in the past. There has only been one person that has made a negative comment, more often than not people are coming over to congratulate me on taking on such a big project and watching daily to see the transformation. Once the outside is done, then I can do the part that no one sees.

As for your brakes, if you have no leaks, and you have brakes, try changing the sensor. The mechanic may be correct.

cdemaris · 04-18-2010, 12:01 PM

jkindt

Do you know what sensor I need to replace? You said you were pretty knowledgable about these brakes.

ErrabundusBus · 04-18-2010, 06:25 PM

My brake alarm decided to go on during a trip down to Alabama a couple of weeks ago. After making sure there were no brake fluid leaks, I pulled the fuse to stop the beeping. The light goes on though. When I start the bus, everything is fine, but if I use the brakes a few times(like coming up to a stop sign) the beeper goes on. Also, if I am turning the steering wheel hard it'll go on. Steering and brake fluid are full BTW. The sensor in my master cylinder(like the one in your picture) has been busted off almost since I got the bus a couple of years ago. My alarm only decided to go on recently.

I also would like to know what the problem is!

jkindt · 04-18-2010, 06:51 PM

If the problem is the sensor, it is most likely this sensor. This is the one that senses pressure in the system and they have been known to wear out or just quit working. I am not sure how much they are worth or exactly how to test them, but if you can get it running without the alarm, then unplug this sensor, the alarm should go off again. I may have that backwards, but like I said, I am not sure exactly how to test it but that is your sensor right there...

cdemaris · 04-19-2010, 05:52 PM

Well I went through and followed all the lines I could trace electrical and fluid. I wiggled, pushed, pulled and looked at them pretty closely. Now the alarm doesn't go off and everything is working great. The problem is I don't know what I wiggled to fix it. I think I will get a new sensor this weekend (the one that you circled).

Redbear · 04-21-2010, 07:46 PM

Quote:

Originally Posted by cdemaris

. . .The alarm is going off constantly now as I drive but not at idle. . . .

Have you considered it might have been a vacuum leak, and the buzzer warning of low vacuum for the brake booster? You should have a vacuum storage tank that will provide boost when you are on the throttle, but maybe the vacuum was escaping before you wiggled things?

ErrabundusBus · 04-24-2010, 09:45 PM

Quote:

Have you considered it might have been a vacuum leak, and the buzzer warning of low vacuum for the brake booster? You should have a vacuum storage tank that will provide boost when you are on the throttle, but maybe the vacuum was escaping before you wiggled things?

Looks like he has hydraulic boosted brakes from the power steering pump.

Have you replaced that sensor yet? I replaced mine today....no more alarm. It cost $9.00 from the local International shop.

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