Runaway Detroit 6-71 - Last night's excitement

[Beatenbo]

A stuck rack would aloww it to rev to govoner be the same as pusing throttle wide open manually. One injector stuck would not allow fuel tp other cyl when rack came back. It would dump too much fuel in just that cyl and would pour the black smoke. My vote is a problem in the govoner box .

[ceieio]

All the oil makes me think something evil happened and the bus was sipping some of its own... blower seal, or broken ring (can the slosh oil into the intake on a 671?).

I hope it is something cheap!  We all have only so many cubic dollars to blow on this hobby, and more bling is more fun than fixing broken stuff, especially fixing it again!

Craig - MC7 Oregon

[DrivingMissLazy]

In the case of the 6-71 I think a rack stuck open allows fuel to all cylinders. In my specific case, I had one injector stuck open that held the rack and all the other injectors open. I believe all the later engines were designed different to keep this from happening.

It was late and dark out so I do not recall for sure what the rpm went to. I immediately hit the shutdown damper and coasted to the side of the road and stopped.

I pulled the valve cover, Loosened the stuck injector, put her back together and returned home on five cylinders. Lots of black smoke after that as i recall. (25 years ago).
I really do not know how many cylinders it was running on when it was stuck open, but I know the engine was running close to governed rpm or above.
Richard

A stuck rack would aloww it to rev to govoner be the same as pusing throttle wide open manually. One injector stuck would not allow fuel tp other cyl when rack came back. It would dump too much fuel in just that cyl and would pour the black smoke. My vote is a problem in the govoner box .

[WEC4104]

Okay, finally got word back from the towing company, and my 4104 is right this moment on the road being towed to my mechanic. They were briefed on the proper towing procedure (coach is aired up, rear axle removed, etc.). I wasn't there to witness this process, but it sounds like they have it under control.

I am also getting ready to leave on a business trip, and will not be checking the board for a day or so. (Some of you are probably thinking that is a good thing.) By Thursday I'm figuring I may have some answers.

[DrivingMissLazy]

Question for you experts.

Is it really necessary to pull an axle with a manual tranny when towing this bus?

Richard

(coach is aired up, rear axle removed, etc.

[/size]

[Beatenbo]

Yes pull drive axle

[DavidInWilmNC]

About pulling axles...  I understand why this is necessary in cars and buses with automatics.  Why is it necessary in a manual transmission bus?  Cars don't need to have axles disconnected; you just put them in neutral.  I don't want to come across as argumentative, but if I ever have to be towed, I'd like to minimize the aggravation without damaging anything!  Thanks.

David

[oldmansax]

I agree with DavidinWilmNC:  Inquiring minds want to know!!
 

[DrivingMissLazy]

Well David at least one other person believes as I do.LOL
I would really like a reason why they should be pulled.
Richard

About pulling axles...  I understand why this is necessary in cars and buses with automatics.  Why is it necessary in a manual transmission bus?  Cars don't need to have axles disconnected; you just put them in neutral.  I don't want to come across as argumentative, but if I ever have to be towed, I'd like to minimize the aggravation without damaging anything!  Thanks.

David

[LUKE at US COACH]

Hi Folks:
Wayne's coach arrived here safely this afternoon.  And yes, it was a frozen injector (from Detroit Diesel) with only 1100 miles on it.  Sometimes S___ Happens.  We spend extra money buying from Detroit Diesel as opposed to an aftermarket supplier, but sometimes still have problamatic parts.

With regard to towing.  I advised the towing company to pull the right rear axle., and run an air line to fill the suspension.  Why??
Just in case they thought they were out of gear but were not!!!  I am quite old fashioned in that I would rather be Safe than Sorry!!!!

Happy & SAFE!! Bussin' to ALL.

LUKE at US COACH

[kyle4501]

RE: Pulling an axle for towing.

These things CAN 'fall' into gear as you are moving them. While not likely, it does happen.

In 1980, the school bus I was driving died & the school district wrecker driver hooked up to it & we both made sure it was in neutral. A mile down the road, as we were leaving a stop light, the tow driver noticed it was sluggish & I heard the bus' engine fan. Yep, it had fallen into gear. It made a mess of the motor & clutch.

Given the choice, I'll take the safe route & pull the axle if I have mine towed. Lots cheaper than a repair bill, but to each his own.

[Casper4104]

I'm still learning here (aren't we all).

Pulling the axle on these old GM's means taking off the 10 bolts on the hub and sliding the axle shaft out right?  Rigging a dust-cover for the open hub.  The big dual wheel set happily idles down the road, and the other side with the axle still in place spins the diff.  If the bus falls back into gear, the diff cluster gears are going to get a workout, but it won't backdrive the engine/trans.

Right?

Casper

[kyle4501]

Pulling the axle .......... If the bus falls back into gear, the diff cluster gears are going to get a workout, but it won't backdrive the engine/trans.

Right?

Casper

Right

[brojcol]

I don't know much buddy, but I know your bus is in the best of hands (Luke at US Coach).  We should all be so lucky to have him so close to a breakdown...

Just my opinion

Jimmy

[Busted Knuckle]

Question for you experts.
Is it really necessary to pull an axle with a manual tranny when towing this bus?
Richard

(coach is aired up, rear axle removed, etc.

[/size]

Don't take this wrong, just because I've been around tow trucks for 30 of my 40 yrs ! I don't claim to be an expert, but have learned a thing or two!
First off the driveline should always be disconnected if the drive wheels are not lifted off the ground! In the old days in cars and pick ups this was not done on a regular basis as it wasn't thought to be a problem, but over time we've learned that the transmission bearings suffer from lack of lubrication because the oil slinger is not turning if the engine is not driving the main shaft!
Cars and small trucks can be towed short distances without disconnecting the driveline but it is not advised and any repitable towing company should refuse to do it for liability issues !
We have always made it a habit to pull the driveshaft on big trucks, however one of our drivers took a shortcut and didn't do it once since he only had to tow a truck 4 miles and it was broke down with an engine failure(supposedly) so he pulled it in with the driveshaft in it and wouldn't ya know the owner of the truck was standing there to witness to transmission smoking and grinding as it was pulled into the bay! (ouch) After a bunch of hassles and a very upset insurance company(ours) and $ 10,000 later the shyster trucking company owner's truck was back on the road (funny thing was the Freightliner dealer found nothing at all with the engine, we were set up from the start and our lazy driver fell for the trap!) ! So always have the driveline disconnected !
I always pull both axles or the driveshaft itself ! Whichever is easiest as a 1/2hr to an Hr of labor can save many $ in an insurance claim whether justified or not!
Another thing to watch for is if the operator decides to take a short cut and only pull the driveshaft lose from one end (hopefully the rearend as I just heard of one being left on the rear-end but disconnected at the trans ouch again many $ in damages!) besure to tell him you've heard from someone who has first hand experience of the tie-up strap failing and doing mega damage to a Monaco Pusher when the driveshaft fell down and tangled with the rear end yoke at 60 MPH tearing out the rear end gears, destroying the transmission, the drive shaft, and taking out airbags, tructural members, and lines & wiring! Again unhappy insurance company and a $ 22,000 dollar check and an unhappy camper 8 wks without his high dollar S & S !!!
If want my non-expert opinion a small amount of time and labor is well worth the lack of heart ache and head ache, also can actually save down time and legal/insurance issues/hassles! FWIT! BK

Oh yeah sometimes the oil slinger is being turned but all the oil is at the rear of the tranny do to the front being raised!