'89 MCI Won't Start

[MCI-89]

Hi,

I've been converting an 89 MCI 102c3, and just a few weeks ago it wouldn't start. Won't even try. The weird part is that I started it and moved it back and forth a week or so before.

When I got the bus the ignition didn't work up front, so I start it using a button in the rear.

Here's what I've tried:

-Making sure it's in neutral, and shifting around neutral a bit.
-New 'start' button in rear of bus.
-Made sure the 'ENG. RUN' switch was on
-Made sure batteries were charged

I'm wondering if anybody has advice on where to go from here.

The batteries are connected to a Voltmaster Model 60 - 50A battery equalizer. I've been trying to figure out what each post should read on the multimeter, and how to measure correctly, just to rule that out.

Any advice on how to narrow down the focus would be greatly appreciated, thanks.

[Crown_Guy]

Too many things to say. You're mostly in the wrong forum to get real information on any MCI Coach. Try the Bus Conversion Magazine site they are folks that convert coaches and can give you much more authoritative answers. I'm a guy whose been driving commercially Crowns and Coaches for 55 years and straddle that divide between school buses (Crowns really) and any coach you can name. The folks here are not generally Coach guys and don't have much to offer. You need a wider forum with more experienced participants who actually own and deal with their coaches themselves.

You should stop what you're doing by using a rear start "button" and find out what the REAL issue is with the failure to start normally from the front at the drivers dash. MCI's all have a switch on the rear mechanics control panel that allows it to be started from the rear while being worked on, and then switched back to normal front start. There can be several reasons to fail to start and you need to deliberately and methodically find and validate that each one is working correctly before moving to the next. For instance there's a switch on the rear panel that disables the starter while being worked on. This along with the "front/rear start" and maybe even the front "engine/run" switches have to be all set correctly for it all to work the way it should.

If there have been "modifications" through the years by those ever clever so-called mechanics interested only in getting the thing out of the shop and back on the road could be causing you all kinds of headaches, and all of this is undocumented and up to you to track it down, figure out what's happening and resolve it back to the normal function as designed. I've seen many horror shows caused by this kind of slapdash crap by mechanics that have usually caused way more trouble than they ever solved.

Very very first thing is to describe exactly what engine and transmission you have in it and any history of failures. It makes an amazing difference to know if the engine is a pure mechanical Detroit Diesel 2-stoke like a 6V-92 or and 8V-71 for instance. As a 1989 I'd guess it's a 6V-92 with an Allison HT-740 4-spd automatic transmission since that was the common as grass engine/trans in use by most everyone at the time.

It could just as easily be a 6V-92/Allison with an all electronic controlled DDEC computer running the engine and transmission combo. You really need to find out and start researching your MCI owners maintenance manual for the Coach as well as getting a complete engine manual and Allison transmission manual too. If you don't have these in your hands you really don't know where to start or how to proceed to find and correct the problems. They will tell you what's normal and give you leads on where to look for your failures. Get those manuals ASAP.

It's also possible that you may have a Detroit Diesel Series 60 4-stroke engine and Allison transmission combo. This was just coming into service at that time and took over with time from the venerable 2-stokes. The Series 60 is a completely computer controlled engine and never had any mechanical only variants. The Series 60 is for my money just about the most perfect and awesome engine and anyone with one is dealing with the best of the best.

I'm not even going to try to trouble shoot your issue here without MUCH more info on what you're running. I would encourage you to check out the

https://www.busconversionmagazine.com/forum for help.

Also if you really want to discuss and get some tips email me direct and I'll give you my phone # and we can talk with a better higher speed data transfer rate than using this method. Oh, and where are you located, little things like this can help. mikemcc2k@yahoo.com

[MCI-89]

Thanks, I will get more specific info together this week and update the post. I guess I was looking for more of a general troubleshooting list of things to look at when you get no crank, no start. I get that each type of vehicle is different, though.

[Iceni John]

As Mike said, if you want help you need at the very least to give us some info first. We're not mindreaders! My Crown has exactly the same engine/transmission/driveshaft/etc as many MC9s of the same era, so if I know more about your bus I may be able to help, perhaps. At the very least you need to spend some time (OK, a lot of time...) exploring your bus and all its myriad systems, familiarizing yourself with all its functions. Look on eBay for any and all MC9 printed info such as MCI manuals, Greyhound drivers' and mechanics' handbooks and guides, Detroit and Allison info (but it's all long out of current availablity from those sources), etc etc. If there are any local bus operators who have or used to have MC9s, ingratiate yourself with them and start absorbing as much wisdom and knowledge as you can, especially from the old-timers. The Blue Bird Wanderlodge Owners' Group has a vast online library of info to download, much of which may be relevant to your bus. Bus & RV Parts has a Jan.89 MC9 Operator's Manual to download. What you need to know is out there. And lastly but definitely not leastly, ask the resident gurus on the BCM and BNO forums, but don't waste their time with vagaries and ambiguities: they're cranky old farts!

Good luck.
John

[ewo1]

Originally Posted by MCI-89

Hi,

I've been converting an 89 MCI 102c3,
.......

The batteries are connected to a Voltmaster Model 60 - 50A battery equalizer. I've been trying to figure out what each post should read on the multimeter, and how to measure correctly, just to rule that out.

Any advice on how to narrow down the focus would be greatly appreciated, thanks.

Here is the owner manual for your battery equalizer...

[MCI-89]

Ok, I've been working on this issue and made some progress.

Here's info on the bus:

1989 MCI 102c3
6v92 MUI
Allison HT740

It has a 39MT Starter, and after doing a bit of troubleshooting, decided to replace the solenoid and relay attached to it. I also cleaned and made sure several connections were solid.

When I bought the bus 'front start' didn't work, and the procedure to start I was shown was to push in a relay on the outside of the bus below the driver's window, then push a momentary switch wired to the starter. That would start the bus.

Funny part is, I went to go do this after replacing the starter parts, and when I pushed in that relay below the driver's window, the bus started! The switch was not engaged in the rear of the bus, and the weirder part is that the 3-switch panel in the rear of the bus had one switch set to FRONT START and another to ENG OFF?!

I shut the bus off and tried to replicate it. Wouldn't work. I tried the usual procedure to start, wouldn't work.

I'm now thoroughly confused, but also feel like I may be getting closer. If anybody has any thoughts on what I could try next, I would appreciate any insights. Thanks!

[Tejon7]

TL;DR: Find a wiring diagram for your bus and save years of your life tracking down electrical problems.

I had a similar gremlin for the first 4 years we had our bus. She would eventually start, but only after holding in the ignition button for a long time while the starter stuttered. It seemed like a bad connection somewhere. After cleaning all connections, I gradually replaced starter solenoid, some corroded ring terminals and wire sections, starter switches (driver's and engine compartment), main breaker, and all my engine compartment switches in hopes of finding a solution.

Just a few months ago, I was lucky enough to stumble across a wiring diagram for my bus. I found a relay that was apparently installed in all Crown buses for many years, but wasn't actually necessary with my bus's particular specs. I had tested that relay before and found it to be working, but figured I'd remove it and see if that changed anything. Voila! Finally fixed.

I have to imagine that somebody on one of the coach conversion forums that Crown_Guy and Iceni John mentioned has a PDF 89 MCI wiring diagram. See if you can find one - it might save you a lot of time.

[MCI-89]

Here is a video

outlining what the starting procedure was.

[MCI-89]

I think I'm making some progress, but have a couple questions if anybody can answer them:

-The bus has a 39MT Delco Remy starter. The starter has a sticker that says 12v on it. Yet I'm pushing 24v into it. I'm guessing this is just something I'm misunderstanding, but is that ok?

-In the same vein, I found what I believe to be the wire for the ignition switch. It reads 24v. I believe I am supposed to connect it to the top post on the magnetic switch relay connected to the starter/starter solenoid. Should it be a straight 24v going into it? I'm just confused because the relay and solenoid both have connections to the main battery post on the starter, which is 24v, too.

Basically, I want to find out if I just connect 24v to the ignition switch terminal on the relay, is that ok and should the bus start? I'm kind of scared to do it, don't want to break anything.

I'm very inexperienced w/mechanic work and am learning as I go. Every large truck/bus/rv mechanic within 100 miles has said 'no way' to looking at it. They said it's a can of worms and only work on newer engines. I've tried getting on the coach bus forums, but haven't heard back from the admins for approval yet.

I also just got a scanned copy of the manual from the previous owner.

Any thoughts would be welcome!

[MCI-89]

Originally Posted by MCI-89

I think I'm making some progress, but have a couple questions if anybody can answer them:

-The bus has a 39MT Delco Remy starter. The starter has a sticker that says 12v on it. Yet I'm pushing 24v into it. I'm guessing this is just something I'm misunderstanding, but is that ok?

-In the same vein, I found what I believe to be the wire for the ignition switch. It reads 24v. I believe I am supposed to connect it to the top post on the magnetic switch relay connected to the starter/starter solenoid. Should it be a straight 24v going into it? I'm just confused because the relay and solenoid both have connections to the main battery post on the starter, which is 24v, too.

Basically, I want to find out if I just connect 24v to the ignition switch terminal on the relay, is that ok and should the bus start? I'm kind of scared to do it, don't want to break anything.

I'm very inexperienced w/mechanic work and am learning as I go. Every large truck/bus/rv mechanic within 100 miles has said 'no way' to looking at it. They said it's a can of worms and only work on newer engines. I've tried getting on the coach bus forums, but haven't heard back from the admins for approval yet.

Any thoughts would be welcome!

Also: I spoke with the previous owner, and he gave me a scanned copy of the maintenance manual, so I now have that.

[Iceni John]

Originally Posted by MCI-89

-The bus has a 39MT Delco Remy starter. The starter has a sticker that says 12v on it. Yet I'm pushing 24v into it. I'm guessing this is just something I'm misunderstanding, but is that ok?

I assume the starter motor is not original - it probably had a 42MT originally. If so, why do you have a 12V starter on a 24V bus? Or have the start batteries been rewired in parallel so the starter now gets only 12V? Does that starter spin very quickly, and/or does it get very hot after starting the engine? No starter motor and solenoid will last long if it's getting twice its rated voltage.

John

[MCI-89]

Originally Posted by Iceni John

I assume the starter motor is not original - it probably had a 42MT originally. If so, why do you have a 12V starter on a 24V bus? Or have the start batteries been rewired in parallel so the starter now gets only 12V? Does that starter spin very quickly, and/or does it get very hot after starting the engine? No starter motor and solenoid will last long if it's getting twice its rated voltage.

John

It is not the original, this one has a 2020 date on it. It came in the bus when I bought it. I get 24v to it, so nothing has been modified. Last night when trying to start it, the relay got really hot and the bay smelled really bad. As of this afternoon, I believe the starter is dead. I did a bench test w/12v, couldn't get it to spin.

The urgency behind all of this, is I need to temporarily move the bus before the weekend. The owner's of the property are having a party and need it out of the way. AAA will tow it, but there are no truck or bus mechanics that will look at it.

So I'm looking at starters to get rush delivered in the next couple days. The question is, can I replace it w/another 12v 39MT or is that not right? The previous owner seemed like he knew a bit about buses, and it was starting fine for the last year (for periodic moves up and down the driveway).

I am unsure of what replacement to get if I don't get the same one that is in there now. The manual has a couple options, but doesn't specify:

42MT/7G-1-39
40MT/7G-1-1
50MT/7G-1-38 (for 8v92) engine

[Tejon7]

39MT is a perfectly fine replacement for the original starter... IF you get the correct voltage. I'm guessing the bus got away with an incorrect 12v model for a while because it wasn't started often and if that motor is anything like mine, it only needs a suggestion of turning over for it to catch and run. I've been waiting for a good deal on a 39MT as a backup for my 42MT(12v, in my case).

The mechanic side of the big truck service places might not deal with you, but the parts department should be happy to sell you a new starter. Just make sure its 24v this time and the bendix/pinion gear is correct for your 92 series. I've had good luck with 'diesel pro power' ordering online, but I don't know if they'd be able to ship to you before this weekend.

Oh, and those other starters your manual mentions would obviously be ok too, I'm just assuming they'll be harder to find these days.

[MCI-89]

Originally Posted by Tejon7

39MT is a perfectly fine replacement for the original starter... IF you get the correct voltage. I'm guessing the bus got away with an incorrect 12v model for a while because it wasn't started often and if that motor is anything like mine, it only needs a suggestion of turning over for it to catch and run. I've been waiting for a good deal on a 39MT as a backup for my 42MT(12v, in my case).

The mechanic side of the big truck service places might not deal with you, but the parts department should be happy to sell you a new starter. Just make sure its 24v this time and the bendix/pinion gear is correct for your 92 series. I've had good luck with 'diesel pro power' ordering online, but I don't know if they'd be able to ship to you before this weekend.

Oh, and those other starters your manual mentions would obviously be ok too, I'm just assuming they'll be harder to find these days.

Thanks, this is really helpful! I was looking at this starter. 24v, affordable and can get it quick. Would something like this work?

[Tejon7]

Unfortunately I'm not the best person to answer that. I believe that particular starter won't work because the specs say it's for a Cummins, which I believe (again, not sure) has a different shape/number of teeth on the bendix. Look for something similar that's application list includes your Detroit 92 series and you'll be good to go.

...Unless they made left hand and right hand rotation 92 series engines, which is WAY out of my pay grade.

[ewo1]

Originally Posted by MCI-89

Ok, I've been working on this issue and made some progress.

Here's info on the bus:

1989 MCI 102c3
6v92 MUI
Allison HT740

I found this manual.. I hope it is useful to you & your bus....
It's only 757 pages of info...

Section 7 of the manual deals with electrical stuff / starter....

Detroit Diesel V92 Service manual 1988

[MCI-89]

Originally Posted by ewo1

I found this manual.. I hope it is useful to you & your bus....
It's only 757 pages of info...

Section 7 of the manual deals with electrical stuff / starter....

Detroit Diesel V92 Service manual 1988

Thank you!

I'm in a time crunch and am going to bite the bullet and by a 39MT Delco Remy 24V Starter. My logic is the bus has been running on a 39MT Delco 12v, and the specs are the same between the two, except the voltage.

Rush ordering and will hopefully install and test on Wednesday. If it works, I can get back to the other underlying issues!

[Tejon7]

Page 6 of the manual Ewo1 posted shows how you can find out if your engine spins clockwise or counterclockwise. Make sure you get a starter that goes the right way!

[Crown_Guy]

All buses with engines straight in are right hand engines. The only exceptions were the GMC sideways mounted V-drive Detroits which were all left-handed engines. All buses today, MCI, Prevost, VanHools, Setra, Volvo, etc. whatever, are all the same. Standard Right Hand, same as all truck engines, mounted flywheel first and running down the road assbackwards....

Every single Detroit Diesel 2-stroke engine no matter the size or model was capable of running in either direction, Clockwise (R.H), or Counterclockwise (L.H.). This was a basic design feature for the entire 2-stroke engine line since they were originally designed to be used in naval and marine installations where each engine directly drove a propeller and turned a different direction. Parts commonality was a huge feature since the engines were identical except for a couple internal parts to accommodate the different rotational direction. Very ingenious design really.

As long as you order parts for an MCI installation it should by default be correct and likely a Right Hand engine. This is as viewed when looking at the flywheel end of the engine. Right Hand means clockwise looking at the flywheel. Read your engine books carefully to confirm and also check out the MCI manuals to confirm and make yourself aware of the installation and nomenclature. Right Handed engines are also what's used in most all trucks as well.

As I said the ONLY left handed engines were the old sideways mounted GMC buses as a patented feature of the GMC product line. None are made today.

And by all means make sure you get the proper 24V Starter. That's critical. And then go through all your wiring and components to make sure all the relays and other active components are still 24V. That's a pure 24V vehicle and the only place where 12V was designed in will be the headlights. All the other lights and active components will be 24V.

[ewo1]

For those of you with Detroits....

So I ran into this webpage that has many links to download Detroit manuals.
Never used this source before but I did click on some of the manuals and the downloads work...free....