Air Leak and Amp Draw (getting to know the bus)

[Bus Busted]

1986 MCI 102A3 W/6v92 manual throttle setup

While waiting to do the heads, I thought I would start on other items. I have found that until the bus reaches 90+PSI both the "Park brake" button and the "Unlock the coach doors" button leak air. I also did a walk around and found 3 cargo door locks leaking to the point you can hear them. They are not leaking at the tube, they are leaking where the shaft slides in and out. Do we rebuild these? Replace? Buy used? Help! (1st picture is of what I call the coach door lock)

Also, while checking the battery cables I found major amp draw (I think), it's over 6 amps with the main switch off and nothing turned on. I went to the door under the drivers side window and unhooked the wire going to the switches (2nd picture). Still over 6 amps. Unhooked the wires to the battery cutoff as two are hooked there and I needed to see which was pulling 6 amps. The larger of the two is pulling 6 amps (3rd picture). Should it be doing this? If not what is the normal amp draw? Is this the one that goes to the starter and if so, what else? (Alt. return?) I am going through the bus and finding things that don't look or sound right and I'm sure I'll need more info soon. Thanks, Jon

[lostagain]

Do you have manuals for your bus? You need the maintenance manual and the parts manual. Indispensable.

JC

[robertglines1]

should be nothing hooked direct to your batt except bat cables.  everything should be hooked after master switch.  MCI guys correct me if my memory has failed me.   Bob

[luvrbus]

If he has a Vanner probably his amp draw people do strange things with those LOL

good luck

[robertglines1]

was a seated revenue coach before he got it.

[Bus Busted]

As far as manuals, I only have the ones from this site   http://busrvparts.com/MCI_Manuals.htm   There was nothing hooked to the battery or the battery shutoff that looked out of place. I will hit it again Friday with better light and see if I can't track this down this large wire/cable better. When I find where it goes I hope to unhook things one at a time until the 6 amp draw goes away. As far as an inverter, it's mostly what Greyhound had in there. There was a radio in the arm rest, but I have removed that so I could start with just the Greyhound mods only. Oh, Any thoughts on the air leaks replace, rebuild, someone want to sell me parts...

[buswarrior]

My bias has always been to replace leaking air components.

My time isn't worth the savings and the risk of failure, in what it takes to find the seals, and disassemble, and break the old original, or have it leak after I'm done.
That outlook may change after I retire and have nothing to do all day but screw with my own screw-ups to pass the time. But for right now, I can't afford to waste that kind of time.
I do not work with these things every day and know what constitutes acceptable core to rebuild and what should be scrapped.

And, more tellingly, the big fleets don't screw around at all, they replace.

MCI and Mohawk are two big name places to get those parts, more research may yield the original vendors.

6 amps is a lot of draw, find that quick, before it kills your batteries.

happy coaching!
buswarrior

[robertglines1]

center picture is that metal cable connector touching your bus bar?  Sometimes those are on shielded cables. short/drain?   bottom pic  wire with yellow wire end attached to batt term?

[Bus Busted]

   Took a break from feeding the mosquitoes and this is how far I got. I tracked the large wire pulling 6 amps to the rear of the bus drivers side (1st picture). Found it going into the side of the rear box via a through bolt (2nd pic). Inside the box this bolt had 3 wires hooked to it, two blk and one red (3rd pic). Tested all three and found the red wire pulling the 6 amps and the two blk pulling almost nothing (4th pic). That red wire (which looks newer than any other wires around it) goes to the terminal block. My next step will be to trace any wire hooked to that block that's pulling 6 amps. I'm just taking this step by step unless someone knows any shortcuts. I'm hoping this will help with anyone else searching the same trouble (large wire amp draw). Anyone seen this red wire before in this spot? Was it an add on? I'll let you know what I find next. Thanks for any help, Jon

P.S. "robertglines1" thanks for looking close. The metal cable connector was not touching the bus bar. Still it looks like it could if the bus rocked a little so I will move it and tape it. The blk wire with the yellow end is the 12volt tap and had very low amp draw.

[Bus Busted]

More info on my trouble, I think I about have it fixed. The red wire went to post "49" in the rear box as already pictured. There are 3 wires on post "49", the newly added red wire and two blk wires. My wiring chart shows one blk wire should go to the POS side of the regulator and the other should go to post "3" of the field relay. So by adding the red jumper they are bypassing the field relay post "3". It looks like the wire going to the regulator is the one pulling 6 amps. I came inside to find out where the regulator was and now know it's on the inside of the 3rd bay, Pass side, up at the top, behind a plate. Went out and found this to be true. Now I need to hook the box wires up and remove the POS regulator wire, put the meter in there and see if it's the regulator pulling 6 amps.

   Also would like to see why they have bypassed the relay. Might be that I don't have a belt on my Alt. Looking at the engine in more detail today, I think this may be a rebuilt. Some parts have dirt buildup and the lack of dirt in some areas make me think this was added and if the old engine had the belt and the new on doesn't then that would explain the bypass. One thing I know is that when the bus is running the batt volts go from 24 to 27 so it is charging, what I don't know is it charging as soon as I hit the switch or is it waiting for the gen light to go out (above 90psi) and then kicking in. My gut says that with the field relay bypassed it's trying to charge as soon as I flip the battery cutoff to the on/up position.

   I have the breakdown of the voltage regulator and if it is pulling 6 amps I should be able to take it apart and see why. Worse case I have to swap out the regulator. I do lab and hosp equipment repair for a living and this kinda work is as bad as that without someone else to send the invoice to !!!

[Mex-Busnut]

I spent several hours on two occasions with a dear friend on the South side of Fort Worth TX over the last ten days. He used to do bus conversions, and I learned a lot. (He no longer does them, because of failing eyesight and poor health.)

One of his great suggestions was to purchase the large battery cutoff switch at the local Camping World. (I think it was around $23.00.) He said buses are famous for coming up with "phantom loads" that will kill your battery, even when you think everything is off.  

They have two versions of this switch: One says "House battery" and the other is "Chassis battery". The house battery one says "Continuous rating 275 amps; Intermittent rating 455 amps; Cranking rating 1,250 amps". It is rated at 48 Volts, and can be wired with cables as thick as 1/0. I only got one for my house batteries, but maybe get other one later.

[Bus Busted]

   Still looking, Found the regulator to be working ok and the 6 amp draw coming from the wire leading to the field post of the alternator. I am still chasing wires at this time and came in for a little lunch. Next I plan to check post "48" in the rear box. The alt wire stops there before heading to the alt (could still be a wire with a bare spot rubbing the frame), then will check where it connects to the alt. While doing a lot of forum searching and general online searching I found this from MCI.

http://www.mcicoach.com/service-support/serinfo/serinfo07K.htm

Highlighted the chart, hit print, print selection, and now have a copy to keep on the bus. Some real good info on the charging system there. This all started with wanting to fix the leaks, both amp and air leaks. As I follow these main wires to their homes I have the good feeling of knowing that other amp draws are of smaller values and seem to be right for the circuit it goes to. Also getting a real good feel for the bus and how other parts look (frame rails, oils leaks, water lines, ect) Heading back out now, hope this story has a happy ending so I can move on to the air leaks.

P.S. Mex-Busnut, I'm sure I will getting one of those soon. I have the main battery shut-off that MCI gave us, but will need the "house" cut-off when I install my second bank of batteries. Price seems right and the need is there.

[Bus Busted]

For those of you with 12/24 volt MCI headlights, you might find this link below helpful

http://www.mcicoach.com/service-support/serinfo/serinfo07G.htm

I found it while looking at MCI HTML, HTM, and PDF pages, so if you like looking at info and recalls that may or may not apply to your MCI bus, you can go to this link.

http://www.mcicoach.com/service-support/serinfo/

First 1/2 page are the PDF files and are mostly FYI, the second 1/2 is the HTM files containing repair and recall info. If this is something the MCI guys already know, sorry for the repeat as I'm still new here and hoping to log posts that if found while searching will help others to an answer. Hope this helps (I know I'll be printing out a few for the "on bus" repair folder), Jon

[Bus Busted]

   I will need to call MCI tech support to be sure, but it looks like a 6-7 amp draw from the field winding of an alt this large might be normal. Did some searching and the field winding is a higher amp item. Plus I tested field Ohms, supply power, and other tests listed in the link from the post above and found the unit to be working fine. This brings us back to the added red wire bypassing the field relay. I feel I need to fix it so that the relay handles turning on that 6amp draw (the way it shows in the wiring diagram). It would look for the engine to be running and up to 90psi before turning on the 6-7amp draw from the field winding, thus not be drawing 6-7amps while the engine is not running.

   Looking at these relays I can understand why they might go bad handling a 6-7amp hit every time you start the bus and get it up to the right PSI. I can see why Greyhound might have bypassed the relay ~ knowing the more the relay is on, the more it moves a hair when the bus hits a bump, and gets pitted every time it snaps on - all of these increase wear X the number of hours ran X the number of buses in your fleet, I get it. I saw how pitted the bypassed relay looked. Still I won't be driving my bus that much and the cost won't be that bad. I'll just carry extra relays and be mindful of bad field relay symptoms. I might also keep that jumped wire around in case of socket failure. So unless I hear otherwise from the MCI techs, this is closed.

Something found while doing my searching, MCI has "Technical Training Webinar's". To check one out follow this link.
http://www.mcicoach.com/service-support/technicalTrainingWebinar/charging011211/charging011211.pdf

To find more click the next link,
http://www.mcicoach.com/service-support/technicalTrainingWebinar/

then click on one of the listed folders, then click on the only PDF file in that sub-folder

Thanks, Jon

[Bus Busted]

Final info.

   Relay, wiring, and mod repaired to look like wiring diagram. Bus amp draw sitting with nothing turned on but the main battery switch = .02amps! Not 6.7amps! Alt doesn't turn on until about 80psi, then the battery voltage goes from 24.3 to 27.5 and it took about 3-4 min to reach 80psi.