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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: WEC4104 on July 22, 2006, 12:42:15 PM



Title: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 22, 2006, 12:42:15 PM
It was Friday evening, and I've got the wife & kids packed up for a weekend away camping. I have only put 1100 miles on a fresh inframe of my 4104's 6-71, and she is absolutely purring. I am cruising westboard on the PA turnpike wearing a big S.E.G.

Everything was going well for the first 30 miles. Then, as I am cruising down a slight grade, I feel I am going pretty fast. I sneak a quick glance at the gauges and see I am doing 70 mph at about 2450 rpms!  I am governed at about 64 / 2200, so I backed completely off the accelerator and still have to brake a bit to lower the rpms. It was a slight downhill grade but certainly not THAT steep.

As I continued on, I discovered that I could run at about 62 mph without even touching the accelerator. Uh-oh.  I jabbed at the pedal a few times wondering if I had a throttle cable hung up.  No difference.  I tried pushing in the clutch briefly, and the rpms immediately shot up.  More uh-oh.

So there I am cruising down the PA turnpike, in thankfully light traffic, pondering my options.  I know from replacing a dashboard light bulb recently that a previous owner had disconnected the EMERG. SHUTDOWN switch on the dash.   Of course, I could just keep driving until I run out of fuel, but remembering that I had just topped of my tanks, I quickly realize that would be somewhere out past Chicago.

I also realize that if I take her out of gear, I stand little chance of ever getting her back in any gear. Likewise, stopping the bus by depressing the clutch is going to take the rpms into the stratosphere, turning my freshly rebuilt 6-71 into scrap metal.  As a test, I depress the clutch again for just an instant. The rate at which the rpms rise makes me quickly rule out the possibility of parking and rushing to the back to block the air intake.

As I continue to cruise west, I keep having flashbacks of the Sandra Bullock movie Speed.

So in a bus traveling at highway speed, which will win out?:  the 6-71 in runaway operation, or the 4104's brakes?  I am not sure I want to discover the answer at some turnpike toll booth.

Up ahead I see signs for a rest area. The off ramp looks flat with a gradual curve, and there are big parking lots for trucks in the back. Quickly, I decide this looks like my best option. I start bleeding off speed using the brakes. I get off at the ramp doing 35 mph, and by the time I am moving through the back parking lot, I am down to 20 (still in 4th gear). I pull into a parking slot and hit the brakes to execute an intentional stall and kill the engine.   Whew! I'm shut down.  Not the nicest thing to do to the engine, but given my options it was the best I could come up with.

I caught my breath, relaxed my "pucker factor", and went back to look in the engine compartment.  There was quite a bit of oil dripping, especially on the radiator side. Some of the wet areas were up pretty high too, although it might have been thrown up there by the fan blades.  I couldn't see any apparent throttle or govenor problems.  The oil level was down quite a bit, but still in the acceptable range on the dipstick.

I am not very knowledgeable about runaway diesels, but I think I have heard that they can happen from the engine running on it's motor oil.   I'll mention that the N60 injectors were all replaced with the engine rebuild.

Fortunately, our family was planning to go to two different places on Saturday, and for the first time in six years, my wife was following in her car. The 4104 has never broken down on us before, and we have never had a car with us before.  :}

So there she sits, in the parking lot of the Rest Area as I await contact with my mechanic. I am hoping I can find a solution that won't require towing. Suggestions from Board members are always welcome, too.  (Aside from "Get the Engine Shutdown switch connected", which is a given.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Mike in GA on July 22, 2006, 02:53:48 PM
Wow! Fascinating situation. Every busnut's nightmare.  Please do tell us how this all works out, since maybe we can learn how to avoid this, etc.  Besy of luck!
Mike in GA


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DuaneMC7 on July 22, 2006, 03:00:10 PM
Wow! Quite a story!  Sorry I have no help to offer, but this is a reminder to us all to have our emergency shut downs in working order.  Good luck and let us know how it works out.

Duane.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: FloridaCliff on July 22, 2006, 03:16:21 PM
Wow, What a story.

And i thought my exhaust leak and fire was scary :o

By the way, great job on keeping your head and doing the right thing.

Having loved ones with you only intensifies the experience,

Please let us know what you find.

Cliff


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 22, 2006, 03:58:17 PM
Ironically, I already had plans to get the EMERG STOP switch operational again, and had begun to start on it.

For several years, I did not realize my switch was non-operational. I was always concerned about the switch location and the fact that it blends in against a bunch of similar toggles. My concern was that it is too easy to hit by mistake. What if I got into a tight city location and, in the middle of a turn, needed to back up a few feet and then pull forward again? It would not be hard to reach for the REVERSE switch and hit the EMERG STOP by mistake. Then I would have to stop in traffic and go back to the engine compartment, reset it and restart, and everything. Of course, it would be raining and at night when I had to do this. 

In browsing the auto parts stores lately, I noticed that toggle switches with flip covers have become popular with the boy-racer crowd.  They take a standard toggle switch and add a hinged cover, like it was a missle launch switch or something. Guess they use them for Nitrous Oxide, or something. I bought one a few weeks ago for my EMERG STOP switch. The color of the cover was bright red, and a little too much for my tastes, but I was able to repaint it the same color as my dash.  I installed it this week, and it blends in nicely with the dash. In the process of installing it I found out that the old switch had not been operational. I think a previous owner had done more than disconnect the dash switch, and I have not had a chance of checking the rest of the circuit to get the newly installed switch working. In any event, I think this will eliminate my fear of accidentally tripping the shutdown. 

Those of you with the dash toggle shutdown switch, I offer that as an easy enhancement.

... Busless for 24 hours and counting.  I'll keep you posted.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DrivingMissLazy on July 22, 2006, 04:29:58 PM
I had the same thing happen on my 4104. I topped a mountain and when I started down the other side, she just kept on going. Fortunately I had my emergency shutdown switch working and got her stopped by the side of the road.

It has been so long that I can not remember how I determined it, but I discovered that my rack was stuck open. I removed the valve cover and found one injector stuck open which was holding the rack open. I just loosened the one injector and the rack immediately returned to the closed position.

I replaced the valve cover and drove her home on five instead six. The only mistake I made was I did not get the valve cover gasket on properly and I had a LOT of oil everywhere when I got home.
Richard


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Casper4104 on July 22, 2006, 07:40:18 PM
Hey WEC, way to keep your cool man, nice job.

My 4104 has a couple of those safety toggles with the flip covers too - the guy that did the conversion put them on the switches that you really REALLY don't want to hit accidentally. (Starter, Reverse, Estop).  They're red for a reason, but I can see your point too.  They're nice, I like 'em.

Let us know how it goes.  I've heard that a slobber tube not draining properly can allow bad stuff to accumulate in a bad spot and that the engine can run away that way.  Something to check? (just repeating hearsay - some real expert chime in here please).

Good luck pal,

Casper


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: bernie on July 22, 2006, 09:30:22 PM
when i drove a truck i bogged the motor and it ran backwards,but it did not runaway
i will check the shutdown on my 4104.thats a scary deal
good luck
      Bernie


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: roadrunnertex on July 23, 2006, 06:43:12 AM
Run away Detroit.
Sounds like it was a exciting time for you.
One of the ways to stop the runaway on any detroit take a wrench and loosen the main fuel supply line.
Another is use a CO/2 fire extingusher spray the CO/2 into the engine air inlet.Please( DO NOT) use a dry powder fire extingusher.
This might be a good time for us folks to check out our emergency shut down system on our coaches.
Folks make sure you do this with the engine not running.
And also make sure that you reset the flaper valve when you finsh your check.
Just a thought on my part.
jlv


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: TomC on July 23, 2006, 06:55:59 AM
A couple of things on runnaways (engines that is).  The newer versions of Detroit injectors-any with a letter in them- have been redesigned so to have spring back to them, so no flapper is necessary.  You won't find emergency flappers on turbo engines.  Also, do not feed the breather tube back into the intake.  With oil mist or a failure the engine will run on oil.  The new '07 engines are going to have closed breather systems where the old road tube is going to dump into an oil separator (another part that will have to be serviced) then into the intake air.  No matter what engine you have, if you have an engine failure- turbo oil seal leak, blower seal leaking, broken or worn rings, etc, any engine runs the risk of running on.  If you have a non turbo'ed engine with a three digit numbered injector, I would keep the emergency shut down in working order.  Like all systems on the bus, they should be in good running condition.  Good Luck, TomC


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: littlehouse on July 23, 2006, 09:55:56 AM
TomC
  How would you stop a runnaway turbo if, lord for bid, it happend. Just want to know because a fuel suttoff switch dose'nt
sound like it would work

Ray with the littlehouse ['77MC8]


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Barn Owl on July 23, 2006, 10:39:15 AM
What would one do if you had an auto and your emergency cutoff was inop in this situation?


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 23, 2006, 11:21:06 AM
Barn:

Took me a minute to figure out you were asking about "auto" as in automatic transmission, (not car). I'm a little slow today.

With an automatic transmission, the question hinges on whether the brakes would be strong enough to hold back the coach as it keeps downshifting. I'm betting there would be no choice other than take it out of gear to get it stopped.

So the best scenario would be if I could get the bus stopped safely in a remote location, get my family quickly off, and run like h***.    From my brief experience, the RPMs rise very quickly with no engine load (just blip your throttle pedal while parked sometime and you'll get the idea).

There are those folks that might recommend breaking out a wrench for disconnecting the fuel line.  They've got bigger stones than mine. I know what my 6-71 sounds like running at it's normal governed max speed.  Tack on an extra 1000 rpm and there is no way I'm going to be standing next to it diddling with a wrench in my hand. Taking the bath mat out of the tub and holding it against the air intake might work. Squirt a fire extinguisher at the intake?  Maybe. (Although mine are dry chemical, not CO2)  So that would come down to a question of "Make a mess out of the engine while risking my own safety" versus "Let the engine destroy itself on it's own"  I honestly don't know which I would choose in the heat of the moment.

Of course, if I had an automatic, it wouldn't take me as long to use up all the fuel in the tank either :}


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DrivingMissLazy on July 23, 2006, 12:15:04 PM
But did he have a runaway engine or just a stuck qccellerator or rack? I do not think he ever took it out of gear long enough to find out. Yes theos babies will sound like a runaway if they go up to the governor but it will really not hurt them.
Richard


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: n4rsn on July 23, 2006, 12:16:22 PM
Looks like you have an injector stuck, like Tomc said.       If you are tryin to do something with it,---- pop the valve cover off, and check the rack. See if it is stuck, or someone has put the cotterpin in the wrong way, and it is sticking in the open position.     Try to move the rack, not forcing it to open and close.   If it is stuck, than you will have to find which injector is stuck, and just take the screws out, and move the little actuator to the side, leaving the screws out.  Make sure there is nothing else restricting the movement of the rack, and put the valve cover back on,  makeing sure it is seated down, and tighten it up.
      Now--  BEFORE YOU START THE ENGINE, PUT THE TRANSMISSION IN 4th GEAR, than statr the engine.   Just in case there is still simething causing the engine to overspeed.

Keep us posted, and I hope this will help a little.
Steve


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: n4rsn on July 23, 2006, 12:20:19 PM
But did he have a runaway engine or just a stuck qccellerator or rack? I do not think he ever took it out of gear long enough to find out. Yes theos babies will sound like a runaway if they go up to the governor but it will really not hurt them.
Richard

He said it went to 2450, and was governed to 21, I think, so I wouldn't take a chance. Check the throtle cable in the rear at the govener, If all is ok, go to the rack next.
Steve


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: NCbob on July 23, 2006, 12:51:12 PM
Fellas, before we start all the panic business about how these Detroit's are subject to runaway...let's calm down and take a good look at not only the evidence of this scenario and the maintenance background of the engine.

Most of these old buses sit for long periods of time doing nothing except for an occasional  startup to keep the owner from feeling guilty.  If they are run, it's generally short trips for about the same purpose.  Engines that are excercised regulary are not susceptable to these types of problems.

Maintenance, the word we hate most for the reason that we're not qualified to run a rack or can't find somone who will do it inexpensively enough to suit our budgets.  Racks and injectors are prone to sticking if not used on a regular basis.  But as Tom pointed out the N or lettered injectors are built slightly different in the the fuel rack of each injector is loaded to go back to the no fuel position.

In this case...Did his engine start consuming it's own oil from the base as an alternative source of fuel?  I think not since he was only down a couple of quarts.

What the other possible source of the problem?  Not too much air for certain.  A stuck rack or one stuck injector which could hold the other 5 in the full fuel position and make the engine uncontrolable in the sense that we normally think of as 'control'.  Would the engine have overspeeded beyond the point of Governor control?  I don't believe we know that yet.

With a Limiting Speed governor the Operator only has control of engine speed at the mid-range. From idle to midrange (low) and from mid-range (High) to No-load RPM the governor is complete control over the engine...unless something is either broken or out of adjustment.  If a cotter pin through the clevis which connects the rack to the Governor operating lever had dropped or vibrated out we could re-construct exactly the same scenario.  But the engine would have gone to full fuel and might have self destructed.
The question really is then...did the governor have control of the engine up to and including No Load RPM?

Obviously the operator was much too busy and concerned about the welfare of his family and the situation at hand to make such a conclusion. Was he headed downhill and thought he observed an overspeed condition beyond no load?

So, logically we will have to adopt a wait and see attitude until a properly trained technician makes a determination as to what happened.

I will repeat a statement I posted some time back.  Detroit Diesel has, for some years recommended the removal of air box dampers.
A properly maintained and adjusted engine will not "run away".  I have removed the air box shut down from my engine so I practice what I preach.  They cause more problems that they ever corrected.

I did not intend for this post to be this long, nor did I intend to represent myself as an "Expert" on Detroit Diesel Engines.  I was trained at Detroit Diesel in Detroit many years ago on both the 53 and the 71 Series.  I've spent almost 30 years running yachts for a living with mostly Detroit Diesels, in pairs, under my feet.  Never, repeat... Never in all those years have I had a problems such as described in this thread.  And I, from time to time, placed a whole lot on the dependability of those engines.  People's lives were the
bottom line...they brought us home every time!

FWIW

Bob


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 23, 2006, 12:54:50 PM
I had my wife play with the throttle pedal while I watched in the back, There didn't seem to be any issue with the cable, linkage or spring return.  I suspect either the fuel injectors / rack, or the engine getting fed a supply of motor oil.

My governor typically limits me to about 2150-2200 rpm.  I saw 2450 driving down the highway on a slight grade.  I used some gentle brake action to get down to 2100 on flat land. As soon as I pressed the clutch in she immediately went over 2400 and I had to quickly let the clutch back out to keep her from climbing further.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: NCbob on July 23, 2006, 01:08:59 PM
"My governor typically limits me to about 2150-2200 rpm.  I saw 2450 driving down the highway on a slight grade.  I used some gentle brake action to get down to 2100 on flat land. As soon as I pressed the clutch in she immediately went over 2400 and I had to quickly let the clutch back out to keep her from climbing further."

"Gentle brake action......."  That tells me that you're one cool headed Dude!  You were in control.  For that I offer a tip o' the hat!

My best guess, if we're allowed them, is that you had one or more injuectors stuck in the full fuel position to the point where the governor no longer had control of the engine....which surprises me.  Because the governor is able to exert one helluva lot of pressure on the rack to control engine speed.  Might I caution you to have, whoever checks you engine, to not only find the problem but to compare very carefully the existing fuel rod from your governor with a new one to see if it is bent, even slightly.

Regardless, you're in for a rack run at best and possibly a governor repair at worst.  Probably wouldn't be a bad idea to pull the hand hole covers and check for any damage to the pistons, rings and liners. 

Stay in control, m'friend...you're a guy to go down the road with. ;)

Bob


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: n4rsn on July 23, 2006, 01:11:27 PM
Bob, I hate to tell you this, but, Here goes.
        As a Detroit Mechanic, Trained by detroit Diesel, in St. Louis, on the 71 series, and the 92 series, I have had 2 seperate 71's to run away, I managed to get 1 stoped, the other broke a blower shaft before it blew its self apart.    Both were caused by a piece of dirt in an injector, jamming the rack in full throtle position.    The one that broke the blower shaft, did not have a working emergancy shut-down.
I would rather reseal my blower, than replace the engine.
Just my 2 cents
Steve


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: NCbob on July 23, 2006, 02:23:37 PM
Clean Fuel, Clean lube oil, Clean coolant and Clean air with periodic maintenance.

I rest my case.

Bob


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 23, 2006, 02:58:58 PM
While this is all speculation until I get a hold of my mechanic tomorrow,  Maybe we can have some fun with this as a real world situation and everybody gets to play armchair mechanic until I find out and report the final cause.

The facts:

In May, I had a fairly extensive (or is that expensive?) inframe completed by a reputable and knowledgeable establishment.  The inframe included replacing the injectors (N60), cylinders/pistons/etc., and I upgraded the head from a 2 valve to a 4 valve. The blower was also replaced.

Since then I have had two 150-200 mile trips, and one week where I put 700 miles on her. No problems.  My only two concerns were the temp gauge has been running cool (155F) and she seems to be leaking as much, if not more, oil since before the rebuild.  Yes, the proper straight 40 wt oil.  During the 700 mile trip I added a gallon too, and there was some, but not as much, coating the engine exterior.

First hint of a problem was the Turnpike incident Friday evening, until then she was doing great, and certainly running better than before the rebuild.

The injectors are definitely N60s (N65 injectors were in it previously, but she was throwing a lot of smoke under a heavy pedal, and I saw no reason to blast Saudi juice out the tailpipe.)

The oil coating the inside of the engine compartment (radiator side) has me concerned.  Based on what I see on the dipstick, I am guessing I am down more than a gallon in the last 100 miles, not just a few quarts.  She was up near full when I started. When I pulled the stick at the rest stop, she was 1/4 of the way up the stick from the low mark toward the full mark. Granted I had not waited a long time for everything to drain back down into the pan.  

While my wife was following me in her car, she said she noticed some smoking and a smell starting at the same time she saw me start to use the brakes on the turnpike straightaways.  You have to understand that asking her to identify the color of the smoke, or what kind of smell it was, would be pretty futile.

Again, I have no doubt that in neutral or with the clutch depressed, she would quickly rev hundreds of rpms above the governor setting of 2150.  ... and I really don't want to find the upper limit.

So what is everybody's guess? Vote early and vote often.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: JackConrad on July 23, 2006, 03:50:34 PM
Ok, here is my guess: Perhaps the smell was your brakes, since you were fighting the engine with them?


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: gus on July 23, 2006, 09:07:36 PM
I doubt if the fire extinguisher idea would work on a 4104 since it has two air intakes.

 I sure wouldn't want to be running around the back from one side to the other with the engine going supersonic.

We had a long discussion about a month ago on the subject of disconnecting the Emerg Shut Off. I think this incident pretty much shows the wisdom of keeping it. There is no way I wll ever disconnect mine and I check it often now. After this, more often!!


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: CraigC on July 23, 2006, 10:06:19 PM
I could not keep the oil level up to the full mark on my last 2 - 671's. They would be 1/2 way between add marks in about 150 miles. If I would leave them 1/2 way down I would not add any more oil for 4,000 miles or more.

When I had a emergency flap value I would check it's operation to see if it worked on a regular basis.

I found it interesting you went years and did not know if it worked. If it is mechanical and you want it to work someday take nothing for granted. Even with regular maintenance it may not work when needed. Just my opinion.

I vote for a stuck injector.

Good luck getting you bus back on the road!!!! Great keeping your head in a unknown  situation.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DrivingMissLazy on July 24, 2006, 04:05:44 AM
I vote for stuck rack caused by a defective injector and I also vote for keeping the damper and checking it often to make sure it works correctly.
Richard


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Casper4104 on July 24, 2006, 06:48:43 AM
Craig - I've had the same experience with my 4104 with 6-71.  Mine likes to sit just below 1/2 way, and anything I add above that level exits the engine in short order.  I'm still wondering if I have the wrong (too long) dipstick.

Ok WEC - it's monday.  Any news?


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 24, 2006, 09:18:52 AM
I was in touch with my mechanic this morning and it is looking like my best option is to have her towed. Checking with my insurance carrier, their roadside coverage includes towing "to the nearest qualified repair facility".  I have indicated that my preferred destination is 60 miles away. So far, they have not said "No", but I need to get this confirmed before I give everybody the green light.

That fact that only some towing companies are permitted to tow on the PA Turnpike adds a twist, and I have been in touch with the Turnpike Commission this morning.

Add to this the fact that there are some special requirements for towing a GMC, and it gets more interesting.  I am requesting an under reach style tow with the air line connected from the tow vehicle, etc.  When I started talking about this they put me in touch directly with the towing company. I explained some of this to the dispatcher, who listened for a while, then indicated she would have somebody contact me. Sounds like maybe the towing will be scheduled for tomorrow.

I've had detailed phone conversations with literally eight different people this morning, and am waiting for call backs.  Sure am glad I'm not sitting on the side of the road somewhere.   

A note on the oil level: Prior to the rebuild, I generally kept the level roughly 2/3 to 3/4 full. Trying to keep it at the full line was a waste, as it would drop from Full to 3/4 in the first 200-250 miles.  After that, useage/loss would tend to slow, and I could easily go another 400-500 miles before she would drop below 1/2. Friday night it took me less than 75 miles to take it down to the 1/4 mark.  I'm not ruling out the possibility of the two items being unrelated.

Stay tuned.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Dallas on July 24, 2006, 09:52:55 AM
At the rate you seem to be consuming oil, it sounds like you may have lost a blower seal along with possibly a stuck rack. Be careful whatever you do.

Dallas


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 24, 2006, 03:28:02 PM
Major gymanistics today with my insurance carrier regarding towing.  Initially they agreed to use one towing company and to take it to my preferred mechanic. We only needed to work out the times.  By the afternoon they did an about face and wanted to use a different towing company and started hunting for a closer repair shop. 

Several conference calls, and discussions with supervisors later, it looks like the second towing company will be taking it to my preferred mechanic.   What is really stupid is the amount of time everybody wasted on this exercise. Using my map program, the distance to my mechanic: 61 miles.  Distance to the mechanic they wanted to use: 57 miles.  Arrrggggh.

Eventually it came down to the fact that my guy would take me right away, the other guy couldn't start work for at least a week. I started inquiring about trip interruption coverages on the policy, and loaner vehicles.  That speeded up the answer I wanted.

Busless 72 hours and counting


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Beatenbo on July 24, 2006, 06:48:34 PM
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 .


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: ceieio on July 24, 2006, 10:52:18 PM
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


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DrivingMissLazy on July 25, 2006, 05:22:44 AM
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 .


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: WEC4104 on July 25, 2006, 11:07:42 AM
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.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DrivingMissLazy on July 25, 2006, 12:31:52 PM
Question for you experts.

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

Richard

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(coach is aired up, rear axle removed, etc.
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Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Beatenbo on July 25, 2006, 02:17:29 PM
Yes pull drive axle


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DavidInWilmNC on July 25, 2006, 02:43:09 PM
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


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: oldmansax on July 25, 2006, 02:47:22 PM
I agree with DavidinWilmNC:  Inquiring minds want to know!! ??? ???
 


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: DrivingMissLazy on July 25, 2006, 02:50:38 PM
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


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: LUKE at US COACH on July 25, 2006, 03:07:11 PM
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



Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: kyle4501 on July 25, 2006, 03:31:48 PM
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.


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Casper4104 on July 27, 2006, 06:05:02 AM
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


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: kyle4501 on July 27, 2006, 09:22:15 AM
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


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: brojcol on July 27, 2006, 11:19:05 AM
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


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: Busted Knuckle on July 27, 2006, 01:10:57 PM
Question for you experts.
Is it really necessary to pull an axle with a manual tranny when towing this bus?
Richard
Quote
(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 ;D

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!


Title: Re: Runaway Detroit 6-71 - Last night's excitement
Post by: ceieio on July 27, 2006, 01:32:07 PM
BK - Good post.. I leared a lot against the day my bus ends up on a hook!

Craig - MC7 Oregon


Title: Re: Runaway Detroit 6-71 - Final Chapter?
Post by: WEC4104 on July 27, 2006, 02:04:40 PM
Well, I am back from my business trip and on the board again.

I also see that Luke was kind enough to post a message with an update on my 4104.  Up until now, I have intentionally avoided mentioning which shop did my 6-71 rebuild.  U.S. Coach has always treated me well (and continues to do so). While we have been discussing and speculating on what might be wrong with my coach, I did not want to name names, out of fairness to them. I have always been pleased with the work they have done for me, and I certainly didn't want any comments misinterpreted to mean otherwise.  Well, now that Luke has posted his update,  and I know what the overall situation is, I can stop referring to him in generic terms.

Luke and I have been in touch a few times via telephone.  My coach arrived at Camp Luke Tuesday afternoon, and they immediately confirmed that I had a stuck fuel injector that kept the rack in a full (or nearly full) open position.  These injectors were fresh rebuilt Detroit Diesel units, and there was certainly no way U.S Coach could have known or anticipated this problem. In fact, it took over 1000 miles of driving for the problem to surface. Parts are on order.

The oil leak problem appears to be coming from the oil cooler, and is unrelated.

I was very concerned when it looked like my insurance was forcing me to have her towed elsewhere. Fortunately, everything worked out, and I was able to get my insurance company (Progressive) to agree to tow her a bit further to Luke.  The help Luke provided in giving the towing company specific instructions on how to tow a 4104 was also valuable.

I look back on the overall situation, and I am absolutely amazed how fortunate I was. Somebody was certainly looking out for me that evening.  Mostly, I am thankful that I was able to "land" her okay with my family and other motorists safe.  People are what is important, and the rest of the stuff is only metal and money.

Folks have complemented me on my coolness, but the fact is I had one big advantage going for me: Time.  When I discovered I had a problem, I was cruising on an interstate in minimal traffic. I realized I didn't have to do anything immediately. I had the luxury of knowing I could keep doing what I was doing for the next 2+ hours, while I pondered my dillema. At one point while I was driving, I even picked up my cell phone and called U.S. Coach.  It was 7:40 on a Friday evening, and I doubted I would reach anyone, but I figured I had nothing to lose.  Sort of my "Regis, I'd like to phone a friend."  Imagine if Luke had been there to answer the phone, I am sure it would have been his most interesting call for that day!

Had my problem been discovered under different circumstances, chances are I would not have had time to think about my options, and I would only have had time to react. I would have probably needed to use the clutch and/or neutral, and would have quickly turned my 6-71 into modern art.

The list of other ways I was fortunate is endless... It was daytime. It was the only time in six years, we have had a second car along with us for the weekend trip. The clouds opened in a major downpour 15 minutes AFTER I left the bus at the rest stop. My towing coverage deemed me just barely within range of Luke's shop.  ... and I could list many more.

Here's hoping that if any of you encounter a "bad" situation like this, you have as many "good" things happen to you.