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09/18/2018 09:54 PM

MCI 9 and Model 12

What to look for on MCI-9, MCI 12
and MCI 102 model Buses

Even though these coaches are  famous for  its
monocoque chassis with all the stainless steel and aluminum.
They also have had some corrosion issues too...

MC 9 -  1978 to 1987  
(Also assembled by TMC)
MC12 - 1990 to 2005....*MC12-  2006  to continued
*Second production run of the MCI 12 was for
Greyhound and Special buyers only... i.e. Prisons, Govt. etc

Do It Your Selfer's...
Check out our
"What Do I Do Now!" Page, it's suggested budgets



On this page :                           Free Copy of MCI 9 Operators or Maintenance  Manual

Front End Area
Power Assisted VS Full Power Steering
Passenger Windows will leak
Luggage Bays
Drivers Side Inspection door
Windshield Rubber
Windshield Wiper Arms and Post
Fuel Door
Battery Door
Battery Box-Vanner 12 /24 Equalizer

Letter Board Area
Marker Lights
Rear End Section
Blower Box Area
Radiator Louvers
Engine compartment
Older 8V71 Detroit Engine
VS     6V92 Detroit Engine
What is a standard DDEC II Engine?


Rear Suspension Air Box Frame
Radius Rod Bushings
What is a dry climate bus?
Air Bag Plating
Door hinges
Rusted older MCI 8
Turn signal lenses

Head Light 24volt /12volts
Door Seals

Click here to go to
MCI 12volt  Head Lights with 24 Volts


Need help???


First timers!!!!....
One of the most scariest, most trying and traumatic events in your life will be Marriage, Child Birth,
 and buying your first Bus.

A little about a 
Passenger Bus known as MCI 9 and it's  identical twin MCI 12.  
The most popular buses in the U.S. with over 75% of the New and Used Bus market is MCI .
MCI's are the highest rated passenger Bus's in: Service, Longevity, Maintenance and in Resale Value .
The MCI 9 was manufactured to last over 3 million miles when other Buses were built to go approximately
1 million miles. The MC9 was built from 1978 until 1987.
In 1984 they introduced the MCI 96 A-3, then in 1985 the MCI 102 A-3

However later Greyhound wanted their old trusted  MCI 9 back.  So MCI started building the same bus again,
but this time they called it the MCI 12.  Built specifically for Greyhound and other Government applications.
This coach was built from 1990 until 1997 with some special applications up to 2006 for certain Government contracts. 
So there are plenty of these MCI 9's and MCI 12's out there with more to come and service parts for another 20 years .
This is why the MCI 9-12 makes one of the best used Bus conversions in the industry

For more info on MCIŽ  Specifications
See below

For those of you who may not know,....
On this style monocoque chassis you only have a front suspension and a rear suspension ..
The middle of the coach is nothing more then a Stainless Steel flat box bottom with stringers and a
 Corrugated aluminum floor to form the luggage bays. This is all stainless steel and aluminum construction...

MCI 9 and MCI Model 12's
Are you familiar with a MCI 9-12  Body /Chassis?....
Get a  copy of a MCI 9 Operators Manual Free
                                                         Back to Menu Top

Free MCI 9 Operators and Maintenance Manuals  



While they are famous for lasting many miles, they too, do have some spots that should be examined for corrosion.
Below are a list of things you may want to look at when  considering a MCI 9, MCI 12, and MCI 102 Bus .
Click on the links below to bring you to that subject
Front End Area
Power Assisted VS Full Power Steering
Passenger Windows will leak
Luggage Bays
Drivers Side Inspection door
Windshield Rubber
Windshield Wiper Arms and Post
Fuel Door
Battery Door
Battery Box-Vanner 12 /24 Equalizer
Letter Board Area
Marker Lights
Rear End Section
Blower Box Area
Radiator Louvers
Engine compartment
Older 8V71 Detroit Engine
VS     6V92 Detroit Engine
What is a standard DDEC II Engine?
Rear Suspension Air Box Frame
Radius Rod Bushings
What is a dry climate bus?
Air Bag Plating
Door hinges
Rusted older MCI 8
Turn signal lenses
Door Seals

MCI 12volt  Head Lights with 24 volt


 Radiators should be the first thing to check ...


   Interior radiator

Check out the radiators..

Winter Road salt is very  harmful and can damage your bus..

If this Bus was exposed to salt spray at any length of time the aluminum fins will start to deterate.
The best way to check your bus is to take your camera, hold it up against the screen over the radiator. Take a picture of the lower bottom 5" of the outside of the radiator.

If it turns out there is some corrosion on the outside fins there will be about 5-10 times more then that on the inside of the radiator. Not to mention the Blower compartment pulling that salt spray into that area and blowing it down on top of the engine.

 If this area is heavily damaged, be careful.

If this bus was exposed to alot of salt spray there will be other damage all over the coach.

Here is a bus we sold and it happens to be in very good condition, but you can see pictures we put up to show items of concern.

1989 MCI 102 C-3 Bus


Front End Area,                                                                                                                  Back to Menu Top
Behind the front bumper is the spare tire area, look in the ceiling of this compartment, check around the drivers foot controls i.e.: brake pedal throttle pedal and other switches. Open electrical circuit box beneath driver window, check for leaks or deterioration. Below this electrical panel door open the service door in front of the left front tire .

See if this coach has power assist or integral steering         
                                 Back to Menu Top
From the 1950's to 1979 and some up to 1983 MCI's  had  power assisted steering .." This you do not want ..."
Power assisted  steering can easily be detected. Open the service door in front of your left front tire. Beneath the drivers window, if the steering gear box has a hydraulic piston attached to the pitmen arm you will see this hydraulic piston. This hydraulic Piston means you are looking at the power assisted model ..
You don't want that at all ..The standard, full integral steering has been available as a standard with MCI buses since 1980 and is just like what you have in your automobile, you definitely want the more modern steering system I would pass on that bus or allow $2,000. for an upgrade .

Beneath the Drivers Side Window,                                                           Back to Menu Top
Here is your 12/24 Volt circuit breaker panel, make sure there is no water damage in that compartment.

In the drivers compartment, make sure the  gauges don't have water damage.
On the left of driver you will have switches. Make sure they work smoothly, check for looseness or electrical short damage .
MCI 12 shown  (note the different style steering wheel, same as the newer 102 's)

Check the windshield rubber,                                                                                         
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MCI 12 shown  (note the square headlights)                                                           
You should not have black or clear silicone smothered all over the rubber seals, that's a sign they had leak problems.

Windshield  Wiper Arms, Check the main post                                              
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Check out  Electric Windshield wiper replacement kits too!
MCI 12 
On the outside of the lower windshield you have windshield wiper arms.
Check the main drive post it can turn left or right in a wiping action but it should not wobble or pull in or out.  If it does you have excessive wear, you will have a problem down the road. To convert everything to up to electric would run about $1,000.00 .

There is a Fuel Door behind your right front wheel
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Lift this stainless steel door (see images below) it should be straight and undamaged.
Make sure you don't see any damage or corrosion .

To the left of that door is your Battery Door,                                                     
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MCI 12 Shown                         
MCI Model 12 shown. Release handle in middle of door
MCI 9 release at bottom of door
Make sure you don't see any damage from a Short, fire, or corrosion.

Vanner Equalizer,                                                                                                                     
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Above the batteries in the same compartment is a  24v / 12v Equalizer / Converter
These Buses  have 2- 8D Bus batteries, make sure all your terminal ends are clean and they don't have heat or corrosion damage.

Below is an example of a Vanner Battery equalizer connected to a pair of 12volt 8D batteries wired in a series to equal 24volt

Battery Door removed                     Battery and Fuel door removed

Close up of a 24v Vanner Battery Equalizer

You want to make sure these wires are in good condition,..

This equalizer / splitter is what gives you 12 volts to run the 12V headlights, cell phone and other 12V accessories. 
The equalizer is what keeps the voltages separate so the batteries will charge equally but yet you still have the
different voltages when needed.
The engine must have at least 24 volt in order to crank,

Bad riveting from Improper
Rubber or stainless steel hinge replacement on battery and fuel door 

  Battery Door,                          Battery Door,

Need help???
Call our free advice hotline..
Call 610-767-8000 

Good Fuel and Battery Doors

MCI 9 Shown, Battery Door, Fuel Door                          Fuel Door                          Battery and Fuel Door   
Take note of the rubber or stainless steel hinge on top of battery and fuel door. It is a common problem for these hinges to have been replaced. But when the installer does not clean excess sealant out from between the skin and hinge, it can cause a problem.
"see image above" When the rivet was drawn down you will get this bumpy look.
If this happens it's almost impossible to repair that bumpy damage.
You will have to replace that skin section to correct this damage.

Above the battery box, look at the
Side passenger Windows, look at the Windows and Window  seals. 
                                      Back to Menu Top
This style of window is very easy to open from the inside. A lot of maintenance people will open them and set a stick out to hold the window open like a canopy. Over the years this has a tendency to expose the seals more often to sunlight. Make sure you look for cracks in the rubber. Over the years these seals eventually start to crack and deteriorate after a lot of use.
This Seal is one of the largest reasons you can get water in your walls and down in the luggage bay.
 ..You  don't want a wet bus !..      See luggage bays and window seals  next ...

After time, The side windows rubber seals dry out                                                                     
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A lot people aren't aware that a bus creates a negative pressure ( vacuum) traveling down the hiway at hiway speeds . Rain and salt spray from the highway will have a tendency to be pulled into the window wall around these dry and cracked rubber seals . When this happens the salt spray will start to soak into the wall beneath the window and sometimes above the window. This wall from the window to the luggage bay is built with mild steel bracing. The aluminum skins on the outside and inside are simply skins over this  steel. If this rubber window seal leaks and salt spray ever gets into these walls and saturates the insulation this wall will rust out.

See if you see any rust marks in the Luggage bays,                                          Back to Menu Top

Although MCI's are famous for their stainless steel chassis. They only build stainless and aluminum in areas where they have had problems with corrosion in the past. For example, the front and rear end of the bus, the under carriage and the surrounding luggage bays would be constructed of stainless and aluminum. But the walls that hold the windows are built of regular steel AND WILL RUST SEE BELOW ...

Luggage Bay Ceiling                                                                         
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    Good                   Good -Stainless Painted   Stainless, no paint, Very good

  Not so Good                Not so good
Look up underneath where the Luggage door piano hinge is attached to the Chassis . This area is all stainless steel and aluminum with steel screws ..If you see any rust from those mild steel screws at all. This means salty water is coming from your upper wall and the windows have been leaking.
Be aware
this means rust in a place that should be dry ..This means your windows have been leaking and the walls have been rusting .Those screws can rust but only if they have been soaking for awhile..  These sample images have been caught just in time but any worse and it would mean you have a serous rust issue upstairs and it could be really bad ..You wont know however unless you open up the walls                                                 

Luggage Bay Door latches                                                            
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At the bottom of the luggage bay compartment. These latches are made of cast iron and will have a tendency to rust. Be aware if you see rust, this tells you its been wet in this area. That's your first warning ..Heed it , start looking how it got wet . That area should always be dry ..continued...
Next look at the area beneath the side windows,                                       
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This is the outside wall we call the letter board area . Make sure there is no sign of water rusting through the pop rivets, due to salt water soaking into the walls from the windows leaking. This means the steel wall is rusting from inside of the Bus.
See if you can find any bubbling  paint around rivets .. This is a sign of corrosion from within too ..

The marker lights on the Roof , Front and Rear Caps .                             
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Sometimes MCI marker lights leak and seep water into the coach. Make sure you check the  front and rear fiberglass cap  rivets and all the marker lights ..see if you see any sign of silicon

Rear  Section                                                                                               Back to Menu Top
This is a description of the rear, Engine Compartment, Blower Box, Radiators  etc.    

The blower box area,                                                                                   Back to Menu Top

When you look at the ceiling in the engine compartment there are 2 clips holding the blower access door. Lift one clip than the other and lift the door at the same time . This is your blower box compartment. Look out towards the radiators from the inside make sure the radiator fins on the inside are cleaned and not corroded, make sure the lower sections of the radiator are still in good condition. Some buses (1978-1980) have mild steel around the turn signals inside the engine compartment, this steel will have rust problems too.

For more images of Blower Box area  
This Squirrel Cage Blower pulls high volumes of air and salt spray through the radiators and blows it down over the engine to the street. The older MCI's used to have a problem with rusting in this area but MCI later from 1980 on  fixed that with stainless steel.
Make sure the right angle gear box controlling the twin blowers is stable, non corroded and does not wobble. . Check your Blower box level plate, this air cylinder will mover the complete gearbox up and down on this plate to keep the belt tight. Make sure it moves right after you crank the engine to tighten itself. There is a 12 psi  air cylinder that keeps pressure on that huge  plate to keep the fan belt tight, make sure it doesn't leak and the belt flops.

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Look for bad belts, corroded copper wiring, any rust spots around the engine, also check on the outside of your radiator. There are louvers in front of the radiator for extreme cold weather and they close automatically. Make sure they are opened by themselves, sometimes people will have a problem with them and will force the louvers to stay open with a stick or something. Also, you want to be aware if the coach has fiberglass scoops attached to the radiators to act as a air scoop. This will tell you they have been experiencing cooling issues. Be careful this bus will probably need new radiators..

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Engines in the engine  Compartment,

Does this bus have the Newer 6V92 -335 HP  or the Older 8V71-  275 HP Detroit Engine ?

When you walk up to the back of the bus, look at the rear doors and back wall.
Look for oil spray, this means you have an oil leak on that engine,
Also look at the alternator, power steering pump, air compressor. Now look on the left side and you will want to look
at your air filter and the filler tube for your automatic transmission make sure that everything is in good shape. To check your transmission fluid its has to be in idle and warm. 
Look at the MCI Operators manual for images of this area .  or Image for this area alone

8V71 Detroit Engine,                                                                                      Back to Menu Top  

Note this Detroit 8V71 V8 has no Turbo or Black computer box

This is a V8 engine with 71 cubic inches per cylinder this is a 2 stroke scavenger intake engine this design requires a super charger or blower to be mounted in the intake manifold. This is the same supercharger  hot Rodders in the 50's were mounting on top of their hot rods. This standard Detroit engine configuration with this V8 produces approximately 275-318 horse power.

However, with bigger injectors, radiators, and a large turbo you can get up to 550 horse power but this is rare .
Mainly used in marine racing                                            

This standard MCI 9 engine is a DDEC II 6V92TA                                Back to Menu Top
(Note: The DDEC black box on top of engine)

Note, This Engine is the Detroit DDEC 6V92TA, it is a  V6...  6 cylinder with a Turbo on top.
This means this is a Detroit Diesel Electronic Control version 2 it is a V6 with 92 cubic inches per cylinder, Turbo Aspirated. Its a 2 stroke scavenger intake design meaning it must have an air compressor or super charger for it to run. This model engine was installed in the MCI 9's from approximately 1980 on to the mid 90's this engine starts at 285-375 horse power. Average HP is 335                                  

With larger injectors, larger radiators, and twin turbo's, this unit can be hopped up to almost 500 horse power ( Marine Racing Only ,...Sorry ) . However the standards are  DDEC II 6V92A with  335 to 355 horse power .
This is what you will see in all MCI 9-12's from 1987 on. The advantage to this newer model is they have computerized injections and timing to create a more efficient engine with DDEC l,ll,lll,lV,V etc. 
The DDEC l  and ll cannot be modified after market, however the DDEC lll & IV and on can  be reprogrammed.

The Rear suspension is called an Air Box frame design.                        Back to Menu Top  

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This means the air bags push air into a large square steel box, this box is attached to the top of your air bags. look at this steel box see if that under coat is still in good shape.
it should look black or dark grey if you see rust or rust marks there should not be much rust anywhere.

Normally you want to buy a dry climate bus                                       Back to Menu Top
meaning the bus did not live in a icy salt spray condition this salt spray has a tendency to rust and corrode bus chassis
Air bag plating, This is where the air bags are capped off                      
Back to Menu Top
and cant allow air to travel in the box frame suspension.
From the 1950's up until the late 1980's Air Box frame  suspension  allowed air to move  up into the Box frame in the chassis. This did offer a very smooth ride the MCI's were famous for but with time they were found to leak. The newer models have been plated from factory.  However plating from the factory also means they have replaced the original air bags too ..
These older bags must be replaced too ..If you don't the Bus will ride like a dump truck . The older bags needed the air box to share the pressure .. so they are a lot harder. The newer air bags are soft and now handle the complete loads without the air box frames..... 

More on  Air Beam Repair or Plating the Air Bags

Radius rod bushings,                Back to Menu Top


More on radius Rods Air Beam Repair or Plating the Air Bags
A radius rod is a heavy 2 inch steel rod that holds the suspension in place so it wont float around .
There are several of these 2 inch rods and they have radius rod bushings. If these bushings wear down the rear end will move around and not track squarely with the bus.

Structural repair to an older MCI 8 before stainless steel                  Back to Menu Top  

Replacing Hinges and replacing  twin doors with a single Salon door      Back to Menu Top

Door Seals  coming soon

Turn signal lenses                                                                                               Back to Menu Top
Front                                Rear 

These lenses can leak with time however you can still buy parts with no problems.

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MCI Specifications

MCI MC-9 - Pre-Owned Coaches MCI 96A3 - Pre-Owned Coaches MCI 102A3 - Pre-Owned Coaches

1973 - 1978

1979 - 1987 plus

MCI 96A3
1985 - 1990

MCI 102A3
1985 - 1991
MCI 102C3 - Pre-Owned Coaches MCI D Series - Pre-Owned Coaches MCI F3500 - Pre-Owned Coaches
MCI 102C3
MCI D Series
1992 - Present
MCI E Series
1997 - Present
MCI F3500  
2000 - 2003
MCI F3500 - Pre-Owned Coaches
MCI G4500
2000 - 2005
MCI J4500
MCI J4500
2009 Conversion Shell
MCI D4505
  MCI J4500

For all MCI specs together go to
Our MCI Specifications page

Need help???
Call our free advice hotline..
Call 610-767-8000    

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