New to me MCI5B and problems I'm having

[Reddog]

Hello all,
  Despite my lack of time to use Thomas, I decided I needed another bus...I know, it's a sickness, but anyway...
  I bought a 72 MCI5B from a very nice lady in Colorado Springs who had used it a a mission bus with her husband and 12 children. The husband had a stroke and the bus had not been used for 3 years. The batteries were down and despite being a nice, nearly completely rust free 5B, no one was going to buy it, so I did. My ever patient and undertanding wife and I went there (about 200 miles away) took some batteries and tools, jumped it off and she fired right up. Everything was fine and off I took for home...now the fun starts.
  This was my first experience shifting one of these rascals and despite my experience in dump trucks, my '41 Dodge Powerwagon and other cantankerous beasts, I never really got on to shifting. Second gear is either worn out from others efforts or the shift linkage is out of adjustment, because you have to hold it in gear and it won't hold gear on descents. Problem #1

Problem #2: I was motoring along great, running good oil pressure and engine temps at about 190. I started climbing Monarch Pass, the last hump home. I was running out of power and faced with an attempt to downshift into second. I slowed and suddenly lost all power. I mean I went from pulling as well as you might expect in third, but losing speed, good oil pressure, no overheat, no smoke (a little from overfueling) to no power. Coasted to the side of the road where there was lots of shoulder right in from of Dotty's Towing. (Man, does it pay to help out ex-missionaries who are having financial troubles due to health issues!)
  No restart...seemed to be the fuel shutoff acting up. Sit on road a while...Will restart and run as long as starter is engaged, but dies as soon as you get off the starter button.  Sit on road a little more. Monkey with rear start switches and fuel shutoff stops acting up. Bus now runs well at idle but will not take fuel, tons of black smoke when foot feed or high idle is attempted, very little RMP gain. (By now about 45 mins has passed and bus has cooled down some too, I don't think it is an electrical issue.?..) Dig around in baggage compartments and find 2 old but good looking fuel filters. What the heck, put on one, restart, same thing...put on the other one, restart, same thing...call friend with Dotty's and ask him to fire up the Kenworth.
  While the KW warms up, we pull the air filters and the hose off of the intake, no squirrel nests. Restart, same good idle, bad smoke, no RPM gain under acceleration. Put it on the hook and leave it idling and tow it home.
  Once here, the bus is still running at idle, but now a fair amount of white smoke is coming out and any attempt to give it fuel is met with TONS of smoke. Parked it and came on to the house.
  So, what has happened and how do I fix it? Seems to be fuel related, but what's going on? Just before the loss of power and dying deal, I was running great all I did was get out of the throttle and it died. No smoke, no clang, bang, thunk or poof. Also, although it is a little moot at this point, is the shifting a linkage issue or am I looking at a tranny with a shot second gear as well?
  Ahh, the adventures of a bus-o-holic...
Doug at 8000'

[Dreamscape]

What engine? If it's an 8v71, check your blower shut down flap. You'll have to reset it by hand if it's been tripped. As you know it takes air and fuel for these beasts.

You can post in your profile all necessary information so you don't have to put it in each time, like you did on your Thomas.

Good Luck!

Paul

[Reddog]

Thanks Paul,
It is a 8V71, I'm new to DD's. Where is this flap and it's associated controls?? Any thoughts on the tranny?

[gumpy]

The batteries were down and despite being a nice, nearly completely rust free 5B, no one was going to buy it, so I did.

Now there's a good reason to buy a bus if I ever heard one!!   

Hi Doug,
Good to see your posts on the board. Seems like I have not seen much from you for awhile. Could me be, though.

Sorry to hear of your problems with your new bus. As mentioned, check the blower flap. It's located in the air horn just above the blower drive. It's held open by a solenoid, and there's usually an emergency shutdown switch on the dash next to the master switch. If you accidentally hit that switch and tripped the flap, it will close and not let air into the engine. You have to crank it back open by hand until the solenoid catches and holds it again. I can't say for sure where you find it on the MC5 because that's a V drive, isn't it? But you should be able to find it just above the blower where the air inlet comes in.

If it's not that, then you may have lost the blower itself.

As for the transmission, I don't know enough about then to assist so can't even hazard a guess. Sorry.

craig

[bevans6]

speaking from experience (the day that I discovered the emergency shut-off flap) it  will not start and will in no way idle if that has engaged, but I guess it could half engage.  White smoke is unburnt fuel, black smoke is burning but too rich, so the common denominator would seem to be no air.  I wonder if the blower has lunched itself if the air filters are clean and nothing blocking the air intake?  How about a critter in the air intake from the rad housing area to the air filters themselves? 

The only thing that holds a Spicer in gear is the spring and ball detents on the shifter fork rail, which is in the cover above the gearbox itself, the dog clutches themselves move freely and there is nothing in the design of the dogs that keeps a gear engaged.  I can imagine  gunk and old lube stiffening up that spring and ball to the point where it is stuck and won't hold the fork in place.  The dogs on second gear engage with the splines on the big straight cut reverse main shaft gear (it acts as the dog clutch for first and second, and also as reverse).  Second gear dogs are only about 1/4" wide and 1/4" long, their nose has a rounded taper aspect to encourage engagement, and it is very possible for that rounded leading edge to wear excessively so that there isn't enough to actually engage properly.

Brian

[Reddog]

Thanks for the good input so far. I'll be at the shop a little later to check the flap, tranny will have to wait until she runs again. Gunk is my first guess and it really help to know what I will be looking for. Doug at 8000'

[harpold700 3]

Check blower driveshaft.

[Dreamscape]

I had the blower shut down flap close on mine going down I-5 from Santa Clarita CA. It was blowing black smoke and very little power. A CHP stopped and said I had 10 min. to get it off the side of the road!

I had pressure washed the engine the day before and evidently I had moved the spring catch just far enough to let go under running conditions. I had no clue at that time, as this was my first DD and my first bus. I found the problem, wired it open and fired it right up. The officer said, "Get it fixed huh, I'll call and cancel the tow". Whew! I sure didn't need that expense. I do not have a solenoid, far as I can tell it never did. I have one, just never put it on!

I got real lucky when I found the problem, could have been a lot worse. Let us know what you find out.

[Busted Knuckle]

Doug,
So far you have ruled out all but the 2 most likely remaining culprits, hopefully it will be the shut down flap. (cheapest and easiest fix!) But it could also be the blower drive as mentioned.

Craig just a note I think that the MC5 is in fact a T drive, but since it is short with no tag axle they use a drop box drive axle like an Eagle.  (but once I thought I was wrong, and it turned out I was mistaken!)
BK 

[bevans6]

BK, in this case you're mistaken, you're not wrong!  5B is a Tee drive, same as all MCI highway buses.  Just less room.

Brian

[wildbob24]

Doug,

The only problem with the blower shaft theory is the fuel pump is driven off the front of the blower. If the blower stops turning, so does the fuel pump and the engine won't run at all.

The emergency shutdown flap is most likely the culprit.

Bob

[Busted Knuckle]

BK, in this case you're mistaken, you're not wrong!  5B is a Tee drive, same as all MCI highway buses.  Just less room.

Brian

Craig just a note I think that the MC5 is in fact a T drive, but since it is short with no tag axle they use a drop box drive axle like an Eagle.  (but once I thought I was wrong, and it turned out I was mistaken!)
BK  

Actually in this case I was neither mistaken nor wrong, but correct! (as usual)
 BK  

[bevans6]

BK, you were of course completely correct about the tee drive, but sadly mistaken about being wrong!

This is actually a clue that it's been too hot too long where I  live....

B

[gumpy]

Craig just a note I think that the MC5 is in fact a T drive, but since it is short with no tag axle they use a drop box drive axle like an Eagle.  (but once I thought I was wrong, and it turned out I was mistaken!)
BK  

I stand corrected (again). For some reason I was thinking Fred's was a V drive, but now that I think about it, I was sitting in it installing his trailer light converter and I could not have done that with a V drive  

[JohnEd]

This NEVER gets old!