Bad air compressor, big air leaks, no air dryer, axle leak, electrical issue. Water & oil in airtank
2024 ж. 8 Нау.
28 932 Рет қаралды
A failed air compressor wreaks havoc on the entire bus air systems. The electrical systems are a big issue we are just digging into.
The unusually high voltage reading is probably caused by the low pressure buzzer creating this reading on your meter. You can confirm this when the pressure builds-up and the buzzer shuts off; the meter reading should then read 24 volts.
That’s what I came to say. Those old style magnetic buzzers could set up some crazy eddy currents.
Yup, was going to say the same. If his multimeter is set to auto the oscillations created by the buzzer will look like an AC votlage waveform and the meter will auto switch to read the AC. It's a clever safety feature for folks working on AC voltages so you don't accidently have your meter on DC, probe a circuit, see no voltage and grab a wire you thought was safe.
I agree. AC spikes from the buzzer. I’m sure that analog meter would show correct DC voltage. But who hs analog meters these days?😊
Not sure that "eddy currents" applies here but the current cannot be instantaneously brought to zero in an inductor. I'd bet that each of the buzzers is a significant inductor. When they open (causing the buzzing) the voltage in their windings has to spike. I'd guess this is what you're seeing. This is sometimes referred to as inductive flyback. That said, although I've seen the lots of places, I'm not a bus mechanic.
I was thinking the same thing, large counter EMF from the buzzer coil.
Scott, hats off to you for discovering a huge need for bus repairs and building a successful business filling that need. I don't own a bus but still love watching the videos.
I’m still a firm believer that dot needs to do inspections on anything that is this big….
I've been a class A driver for 24 years and I've always felt that anything over a one ton motor home or not should have to go through scales for inspection and have an air brake endorsement for reasons like this. Motor homes are built on truck chassis and most people I've seen over the years don't know anything about air brakes or like spending money on them because they are expensive. Absolutely stupid.
DOT operates under the Commerce Clause of the US Constitution. These busses are now used for private use, DOT has no jurisdiction over traveling in your private automobile. Why give them those powers... If so they could come after your personal car or truck next. Freedom comes with responsibilities, people just need to have accountability for their actions is all.
@@chevrolet402. I agree. I’m a full time rver and have been working in rv resorts for a few years. I do not understand why the owners of the big class A’s with air brakes can drive these rigs without any training or air brake endorsement.
@@patbullard9276 The ones that get me are the old retirees when you pull up next to them on the highway and you can barely see them over the steering wheel 🫣 Nothing against age of course just saying.
@@shrconstruction i see no difference in requiring dot inspections on anything that is built on a medium duty chassis vs annual inspections on passenger cars.
No hair dryer! How barbaric!! The horror! Quick, let’s get a gofundme started.
I I had an older bus, only Scott or his staff would touch it!
Something often overlooked when dealing with flare connections is the angle of the flare. There are two commonly used angles and they are 37° and 45°. Automotive hydraulic brake lines are normally 45° and AN & JIC fittings along with refrigeration lines are 37°. The oil feed for the alternator seems like it would be 37° since it's more common for that type of fitting. A couple of years ago I got so tired of using those old archaic flaring tools that I gathered up all the ones I had and scattered them in the field behind my shop and ordered a brakequip set with both 37° and 45° dies that go up to 1/2". I make a ton of stainless hard lines for brakes lines, air lines and fuel lines. I don't like using copper lines on automotive appliances due to copper cracking from fatigue and they can become easily kinked due to road debris.
I’ve watched your channel with much interest for a while now, yet I don’t remember a segment where you had to deal with electrical issues. My heart sunk when I’m watching you test wires and then look at diagrams. What a nightmare!
I love and hate the fact that you have a lot of MC7s in your videos. Hopefully someday I can get mine to you.
Love these videos, good job once again. ✌️❤️😁
Inductive spike - when the buzzer contacts open, the rapidly collapsing magnetic field generates a brief HV spike (basically like a tiny ignition coil), causing the crazy readings on the meter. I’m surprised there’s not a freewheeling diode (a ‘backwards' diode) often put across the coil of a DC operated relay or solenoid that provides a path for the energy put out when the coil is switched off and the field collapses. It prevents these crazy spikes and reduces contact arcing.
That thing was basically an old-fashioned "door buzzer", which is just a relay with a heavy contact arm. The assumption was that the source was robust enough to handle the back EMF being dumped into it. In those days there weren't silicon diodes. A selenium diode would be physically about the same size as the buzzer, would be fairly fragile, and would have a high enough series resistance to not be too useful. So no diode was the obvious choice. I think the problem is that he is powering this with the Power Probe. It almost certainly has a diode from the 24V source it is supplying to the probe tip. So it will supply *at least* 24V to the tip. If the line it is powering wants to generate more (the buzzer) there is nothing to stop it from doing so. The normal connection thru the 6A breaker would have the whole battery shunting the voltage down to 24V, so the problem wouldn't happen.
@@lwilton Good point - if it were connected directly to the bus' electrical system, the battery would likely act as a clamp and hold the spikes to a much lower level.
I don’t understand how it’s cost effective for you to clean disassemble and rebuild the AD9 at your labor rates when a new one is relatively cheap, it’s like rebuilding a D2 governor you just throw in the scrap heap and put a new one on. I am a fleet mechanic for a highway department in NY. So our stuff is always rusty from road salt so we do not rebuild any of it included brake chambers , and slacks, we use only meritor bonded shoes ,so rust jacking isn’t an issue. Love your channel,and the work you do.
A real bendix 24v ad-9 is $500. A cheap quality clone is $150. But 24v isn’t as easy to get. Waiting a week to get one cost time too or just rebuild it in an hour and also inspect it at the same time
I used similar flare tool and it couldnt do steel line without heat and bought equilevant to eastwood professional brakeline and tubing flare tool and let me say. It was one of the best purchaces i have done.
That air compressor water that accumulates in the tank and filter/water separator in the factories where I used to work I always used to sarcastically refer to as “sweet water”!
That electrical wiring - water etc - makes my head hurt.....lotta hours could go into it.
Hi, when the compressor is passing that much oil the main outlet pipe can also become heavily clogged with carbon due to heat build up in that pipe. Something to be aware of. Cheers.
Have the exact copper line on our alternator crack and break off about 2 years ago. Worst part is it happened while driving in the middle of nowhere and blew all 7 gallons of oil out😬
That sucks
With no support.... it will break again. The entire line has to maintain the same frequency otherwise it will work harden. Can take a very long time to occur... but that phenomenon at play.
Carry a spare line
keep the clips coming
If you can hook up access to your shop air the clean air should remove all the wet contaminants.
Good luck
The high voltage you're seeing is due to a coil somewhere. That is acting like a transformer. Similar to a ignition coil increasing the voltage to a spark plug.
The high voltage your reading is from the buzzer sending back EMF or voltage spikes from the arching of the buzzer contacts it's the same way as a buzz coil works in a model a
Mr. George. We have no 9/16.😊
If i was in a hurry i might have just said 5/8 it is when it threaded in…
Use old fashioned voltmeter for dc measurements. Simpson brand comes to mind.
Or... use a diode...
Mili volts ? Maybe. 🤔 I didn’t see the symbol for MV on you meter but that would be strange to be generating that much voltage there. Good luck.
Back EMF from the buzzer. Definitely volts.
What happened to the nice older man and his huge fleet of busses in Minnesota? I think it was. He loved those busses, me too.
If you’re talking about Bus Old Man Phil, I believe he passed away a while back.
For me ,I would use nylon hose and reroute them tank drains to a readily accessible area just a thought
The pull cords are run to easily accessible locations
can you use a nice new copper line /as short as it is ,
I don’t have any 3/16” copper line
Is it time to get an Ultra sonic cleaner for washing dirty parts?
How big? 3 foot or larger? We deal with really big parts
I swear, some of theseuy everything. Hows your tractor holding up? OK I hope. viewers think you can b@@BusGreaseMonkey
That is hilarious.
Is that bus legal with a cracked windshield?
Is that... blah blah blah...
Interesting-oil cooled generator on that 'ol girl. Thought MCI used belt driven & blast cooled generators on the MC-7 & MC-8 buses-at least the ones I played with as a young man way back in the late 1970's.
It’s a transplant from a fire truck i think.
🙂
I'd go with a new AD9,
It’s good as new now.
😃😃😃👍👍👍
Electrical gremlins ⚡️👹 yuck
You need an meter that reads ture RMS that's design for electronics that's why you are getting all the odd readings
That's literally what he's using lmao. His problem is feedback from an analog buzzer.
cant hear you speak louder. Im wasting my time if I cant hear what your doing ,CYA