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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Zephod on December 13, 2014, 12:00:32 PM

Title: strange noise
Post by: Zephod on December 13, 2014, 12:00:32 PM
Odd motors: http://youtu.be/SgnaWZoTs68 (http://youtu.be/SgnaWZoTs68)

I put the key in the ignition on my 1995 carpenter international 3800 dt466 and turn one click and get an electrical motor noise. Its not the starter - I haven't turned the key that far. No air brakes either. What's the noise and why do the gauges all max out?
Title: Re: strange noise
Post by: luvrbus on December 13, 2014, 12:10:16 PM
Does that have the Hydro-Brake system or air
Title: Re:
Post by: Purplewillie on December 13, 2014, 12:30:53 PM
I believe Cliford is on it...again!
Brake booster.
Mark
Title: Re: strange noise
Post by: baker4106 on December 13, 2014, 04:29:42 PM
I thought you said air brakes.   Noise is brake booster when engine is not running.   Have three of them at my church.   Brakes should work without engine running.
Title: Re: strange noise
Post by: Zephod on December 13, 2014, 06:10:50 PM
A brake booster? What is its purpose? Why is it running when the handbrake is on?
Title: Re: strange noise
Post by: TomC on December 14, 2014, 10:07:13 AM
Hydraulic brakes on a truck/bus work with the power steering. No engine running, no brake boost. So they have an additional electric motor to power the brake booster when the engine if off. It is only supposed to work if you have your foot on the brake. If it is running all the time, the pressure switch in the unit is bad. Good Luck, TomC
Title: Re: strange noise
Post by: Zephod on December 14, 2014, 03:27:08 PM
Highly likely for a neglected bus. I know it had some bad neglect before I bought it. The back tyres were horrific. Now they're merely terrible after I made the previous owner change them before I bought the bus. I suspect I'd have been better off trying to find somewhere in Augusta to change the tyres and get $1,000 off the price.

I'm going to have to make a list of things that need attention. How does one change a pressure switch or check one? Where do I find it and what does it look like? On that theme, the bus has a governor that just restricts fuel flow. How do I adjust that so that I can keep up with the traffic?
Title: Re: strange noise
Post by: chessie4905 on December 14, 2014, 04:47:18 PM
   Remember that most buses of that type have rear axle ratios of 5:29 to 7:20 to one. The governor is controlling excess engine rpms. If you want more road speed, you'll most likely need to do a rear end ratio change. Block the bus from rolling, jack up the duals on one side, and with trans in neutral and driveshaft brake released, have someone rotate free duals EXACTLY two revolutions while you count the revolutions of the driveshaft after marking it so you can accurately count. Repeat to verify your result and then report the result to us.
Title: Re: strange noise
Post by: baker4106 on December 15, 2014, 04:55:45 PM
Booster noise should always be there when engine is not running but not when engine is running.   If you step on the brakes when engine is not running the noise will get louder.   The video matches all our buses on start up.   Our buses with 444E's will run 65 against the governor.
Title: Re:
Post by: Zephod on December 23, 2014, 01:58:11 PM
Ah... I stomped on the brake and the noise did indeed change. It IS a brake booster. Problem solved.