I love the smell of Diesel exhaust in the morning P8M4905A #724 she cranked

[mike davis]

 

I have more questions now ,THANKS all for your help

OK after straightening out 50 some odd feet of battery cables and connections and getting the right power to the starter she fired on the third crank. 

But, she did not air up, and I also heard a knocking noise, but it seemed like it came from the air compressor not the engine.  When I started really looking hard I noticed the air throttle piston and rod had been disconnected from its mounting. 

Here's where this really diverges from my TDM.  Is the air pressure regulator the approx. 8in long round cylinder bolted to the side of the air compressor facing the rear?  If so, is the screw with lock nuts the pressure regulator adjustment?  I did unbolt it and noticed a path directly out of the top of the head of the air compressor.  I did not feel any pressure there.  Also, I disconnected the air compressor intake tube from the air cleaners and felt a little pull on the palm of my hand at the air compressor air intake tube I guess it would be.  Both the air compressor and, if I believe I'm right, the regulator have been replaced fairly recently in the running history of this vehicle.  The regulator looks like it's even newer than the air compressor.  There's a picture of all of this on the Yahoo Bus Nuts group photo album "Future Motor Coach operator in training". 

At approx. 1400RPMs on the motor the most the air pressure gauge on the rear engine control panel moved was to 15PSI.  I know on my TDM there was a primary air shut off valve and a 3 way air pressure valve.  The three way worked tank, system or dump.  I take it this system is different.  This is a pump down instead of a pump up system??  Are there any tricks?  Short cuts?  That I could take to bypass the regulator and see if I can get the air compressor to pump air? 

I also saw some corrosion, not horrible, but I did notice some of the electrical relays in the access compartment underneath the drivers feet were rusted through. 

I found 3 air tanks so far.  Small one in the access compartment under the drivers foot.  One above the batteries in the forward battery compartment.  And one in the bay closest to the front on the drivers side.  Are there more?  And could somebody tell me where the blow off cocks are to these tanks.

Mrs. Davis, the widow that owns it and were negotiating with was extremely happy that I got it fired up. 

I did for a second push the transmission selector forward into forward and did hear the transmission for a second attempt to engage.  I believe it's an electrical relay to engage it.  So, I guess it will try to pull?  So if it can just drag itself up off the ground now we just might be getting somewhere. 

Thanks everyone for all your help. 

Mike

[Tenor]

Congratulations Mike!  It's always and adventure starting one that has been sitting for so long.   

As for the air pressure, they are a positive air system.  If I understand right, you did have the governor off and you should have had LOTS of air coming out.  I suspect that the compressor or the drive gear may be toast.  I don't remember if these use a fiber gear, or metal.  Let's hope it's a bad compressor.

As for air tanks, there are the ones you found, and mine had a petcock on the bottom that you just twist open to drain moisture.  Did this bus have the tag axle?  If it did, there is another tank between the frame rails in the rear luggage bay. 

As for corrosion, do you see light pitting, or chunks of Bondo?  If the electrical  in the drivers panel is rusted, expect that the floor is toast up there.  Also, expect that the body around the windows has rotted away.  I attempted to fiberglass mine in and had no luck.  The small window behind the drivers window also had rusted badly.  Easily 30 percent missing, but filled with bondo.  Check carefully!

How did they install the RV style windows and that MCI window on the driver's side?

Even though many of us have given warnings about this bus, you are helping out the widow by giving her and idea of the vehicle's condition and also giving yourself some great experience.  I looked long and hard at an MCI 7 that was just around a corner from a buddy's house.  My buddy had also owned an MCI 7.  I discovered how much they can rust if left outdoors in the dirt for 18 years!  I did later pull a bunch of parts off of it for mine before it went to a scrap yard.  That's another thing to think about - this could be a good parts bus if you find a different 4905.  Have fun!

[roadrunnertex]

air tanks? 
Left tool/steering compartment under drivers seat floor area.
Drain valve located on the bottom of the tank.
2 tanks upper battery compartment drain valves located behind the fuel tank filler door.
A large air tank is located behind the rear aft bulkhead of the 3rd baggage bin. drain at bottom of the tank.
A small odd shape hot air tank down stream from the air compressor discharge line drain on the bottom.
The round thing on the side of the air compressor is the governor.
It might be sticking.
Or the air compressor coupling might have failed.
Hope this helps.
jlv

[mike davis]

Congratulations Mike!  It's always and adventure starting one that has been sitting for so long.   

As for the air pressure, they are a positive air system.  If I understand right, you did have the governor off and you should have had LOTS of air coming out.  I suspect that the compressor or the drive gear may be toast.  I don't remember if these use a fiber gear, or metal.  Let's hope it's a bad compressor.

As for air tanks, there are the ones you found, and mine had a petcock on the bottom that you just twist open to drain moisture.  Did this bus have the tag axle?  If it did, there is another tank between the frame rails in the rear luggage bay. 

As for corrosion, do you see light pitting, or chunks of Bondo?  If the electrical  in the drivers panel is rusted, expect that the floor is toast up there.  Also, expect that the body around the windows has rotted away.  I attempted to fiberglass mine in and had no luck.  The small window behind the drivers window also had rusted badly.  Easily 30 percent missing, but filled with bondo.  Check carefully!

How did they install the RV style windows and that MCI window on the driver's side?

Even though many of us have given warnings about this bus, you are helping out the widow by giving her and idea of the vehicle's condition and also giving yourself some great experience.  I looked long and hard at an MCI 7 that was just around a corner from a buddy's house.  My buddy had also owned an MCI 7.  I discovered how much they can rust if left outdoors in the dirt for 18 years!  I did later pull a bunch of parts off of it for mine before it went to a scrap yard.  That's another thing to think about - this could be a good parts bus if you find a different 4905.  Have fun!

Tenor,
I agree, a lot of people have told me to be extremely cautious about this coach.  One of the things I look at about this one is if I can move this parts bus to Tucson under its own power.  Then, find a PD 4501.  I at least have the 8V71 which it did not smoke very much.  I ran it for probably a half an hour.  Oh, one question off the top of my head.  Is the Radiator cooling fan variable, thermostatically controlled? 

So I guess the next step would be pulling the compressor which is extremely simple.  Can the rebuild kit be bought for $100 or less? 

This particular coach is not the coach of my life's dream.  And since this has started I have probably spent 30 hours looking for another coach that I can afford. 

The particular attributes this one possesses is the ability to work on it where it is for as long as I need to.  It's only two miles from a basic parts store from there.  I might be able to press the deal and we might be able to live in the RV and the coach while we do it.  Which would reduce my gasoline expense alone by $300 a month.  The coach has three roof airs and the RV has one so I think we'd be pretty comfortable.  Plus the Onan diesel generator 14/16? KW is worth what?  $500?  $700? It does have complete usable bathroom and tub.  New fridge, nice new stove, but no oven, just a range top, oh, we've got an oven in the RV.  I know I'm juggling the conversion vs. mechanical but with two small kids, you know. 

So I've come down to this thinking.  Can I make this parts bus move 2300 miles in 6 months?  And, meander around the area there until we find a piece of property to buy and put it on? 

I'm saving 1K by it's location.  As an example, that $4000 one in MI would cost me at least a K to go get by the time I'm done. 

I sure do hope God drops one out of the sky before I go way far in this, but if I can get it to air and feel that it can make the trip if I baby it, I think we'll do this one.  Because, what would I lose?  I could always strip it and junk it after I pull off all the parts for $15-1600.  So, $2500 for the ability to move myself, my family and all our stuff to Tucson and live in it until we get our crap together down there. And with three roof airs I'll go to Tucson in July or August.

I will continue looking tonight for another coach, but this one sure did sound nice and the entire exhaust system is new. 

Any idea what a new or used air compressor for this one would run? 

Thanks again everyone

Mike

[mike davis]

air tanks? 
Left tool/steering compartment under drivers seat floor area.
Drain valve located on the bottom of the tank.
2 tanks upper battery compartment drain valves located behind the fuel tank filler door.
A large air tank is located behind the rear aft bulkhead of the 3rd baggage bin. drain at bottom of the tank.
A small odd shape hot air tank down stream from the air compressor discharge line drain on the bottom.
The round thing on the side of the air compressor is the governor.
It might be sticking.
Or the air compressor coupling might have failed.
Hope this helps.
jlv

jlv

thank you

   I guess I should take off the compressor and look at the coupling On my TDM the air reg was up on the firewall



                       mike   

[Tenor]

Mike,
I really don't know about cost on the compressor.  Mine had been replaced by the previous owner.  Someone else here will know, or contact Luke at US Coach.  He'll have the parts.  Just do a search on this board for his number.  You'll also want to talk with him about the radiator.  You also may see what a local radiator show would be willing to do to patch up this radiator on a temporary basis.  I don't put a lot of faith in this idea, and many others will caution against it.  The generator is a nice addition and is certainly worth some dough. 

As for the fan, mine was a mechanical drive.  Some later ones used a fluid drive.  The housing for the fluid drive looks like there is a Frisbee put in the shaft area.  I think it acted like a torque converter on an automatic tranny. 

Please let us know the condition of the tires, (where visible), the floor above the bays, details on the corrosion.  Take as many pictures (not blurry ones!) and post as many as possible.  It will really help us all out.

Something you may not realize, - I understand that 4501's were a "t-drive" driveline, like in most other buses.  All of the rest of the GMC line used the "v-drive" system and the engines in these two systems run in opposite directions.  You can convert them, but it is almost to the point a complete rebuild.  I hope the Scenicruiser guys pipe in here!

Don't put any money into this vehicle unless the widow is paying!  Get her quotes for parts, but it is up to you whether your time is free to her.  She'd have to pay someone to do this for her.

Back to the genset, make sure it runs and powers up.  Check the air conditioners and all of the 110 stuff.  Give us a report.  It sounds like this is very important to your situation.

Do you have a voltmeter?  You need to check to see if the bus is charging.  Did you check all of the lights yet?

Another thing, can you tell how the bus is insulated?  If it is the original stuff, it's no good, and you'll need all 3 air conditioners working to keep the temps down in Tuscon.  I've never stayed in one other than in Michigan, and with only one working good on a 95 degree day, we were dying!

How does the oil look?

I would make a big checklist using the posts we have made, take it with you the next time you go out there, write down every answer you can come up with, take corresponding pictures, and then let us know what you found out.

Good luck!

[Hartley]

Mike,

Error in the thought pan there...


The engine from the 4905 will not work in the PD4501

The V-drive is a left hand engine, the T-drive 4501 is a Right hand engine...

Also most parts will not be interchangable from completely different coaches...

Dave...

[John Z]

I'm betting the knocking you heard was the compressor. So i would wait to pull it off to check it and the coupling. I would first check out the govenor. Good luck.

[gmbusguy1]

Mike, I do have a couple of used air compressors in stock, If you need a a drive coupling we stock new fiber/composite gears


also if you replace the governor make sure you buy a High Temp D-2, most common are not high temp used on buses

hope this helps


Chris

[mike davis]

Thank you everyone,

My wife has to go to work shortly and she normally types for me, so I am going to have to respond to all the posts in this one.

First, if I pull loose the air Governor the air compressor should just run free, am I correct?  In other words, continually charge the air system?

next, could you all please send me either the cost of a used air compressor and air governor or please tell me if there is a rebuild kit available for the compressor.  I'm a journeyman HVAC tech and I've rebuilt large open carrier water cooled compressors so I think I could get through a rebuild of this air compressor. 

Tenor, I'll do a full systems survey within the next couple of days and take a whole bunch of pictures.  Today I was concentrating on making the motor go around.  Tomorrow I'll go over and start checking out the air compressor and possibly start hooking up shore power or trying to start the gen set.  I kind of think of it financially this way, it'd probably cost me $500 dollars just to survey another coach.  So, my time, I agreed initially with Mrs. Davis that I would handle figuring out what was going on with the coach because she really has no idea and I believe she is an honest and fair woman.  I've already brought up what I was told here about the scrap value, etc. if it was incapable of driving off. 

So my next steps should be to pull off the air governor, see if the compressor runs free.  If not remove the air compressor, check the coupling.  If the coupling is good, then the compressor is dead. 

As per oil, brand new Delo 40W correctly filled.  Looks so golden and pretty.  Damn, I'm addicted to coaches.  I even love the smell of delo on the dipstick when it's new.

The electrical system does charge.  Through the blade switches when the coach was running and all the systems stayed up.  About 3/4 of the lights came on including the rears.  Got turns and flashers also. 

God, what else did I look at today?

The rear engine control panel does need to be reworked, but the one in the first bay behind the battery compartment looked pristine.  Did notice a little bit of corrosion in the wooden floor, but the bay floors were solid enough to hold my heavy butt and not budge.  And I beat them with a tire buddy and it didn't go through, and no big pieces fell off underneath it either so I guess that's a good sign.

Thanks, got to take my wife to work

Mike

[dparker]

mike,

once i had salvaged semi that i purchased as a parts truck - as i was taking it home the air compressor quit compressing -- never figured out why (bought the unit for wheels, transmission), i would go from service stations to service station and blow up the tanks up and drive it till the air went under 60 psi, this got old so - had one of my guys bring out a small air compressor (electric pancake type) bungee corded it and a small generator on the walk plate behind the cab and went to the house -- Now i am sure that this was not DOT approved, would not have passed any inspection, but i got home and did not have a tow bill -- just an idea if you are going on a one way trip -- you already have the genset --

just an idea --

[roadrunnertex]

Remember- Before you remove the air compressor drain the cooling system.
Above and forward of the engine you will notice 2 hand wheels/valves that will shut off the coolant to the coach heater and defroster core.
Be sure you close these 2 valves before draining the engine coolant.
Note there is a drain plug on the lower radiator tank.
you will not have to drain all of the coolant out of the engine just enough to keep the coolant from running out of the supply and return coolant lines to the air compressor.
The air compressor will likely be a Truflo 600 compressor.
Let us know if it's the compressor or the coupling that's bad.
jlv

[mike davis]

mike,

once i had salvaged semi that i purchased as a parts truck - as i was taking it home the air compressor quit compressing -- never figured out why (bought the unit for wheels, transmission), i would go from service stations to service station and blow up the tanks up and drive it till the air went under 60 psi, this got old so - had one of my guys bring out a small air compressor (electric pancake type) bungee corded it and a small generator on the walk plate behind the cab and went to the house -- Now i am sure that this was not DOT approved, would not have passed any inspection, but i got home and did not have a tow bill -- just an idea if you are going on a one way trip -- you already have the genset --

just an idea --

     
dparker


thank you
there is power right there and an male air fitting for an air hose on the air tank above the battery comp. Plug in home compressor to power ,Cupple air line  See if bus raises up and if brakes release

that is my next step Simple

                  thanks

                           mike