Auto Shutdown on Engine

[FloridaCliff]

On another post there was some talk about disabiling the auto shut down features on a mechanical engine.

I have one and never really thought about it.....

So, just curious what others have done with there Mechanical or Computer controlled engines.

Please vote and comment...

Cliff

[mikelutestanski]

Hello:    Some thoughts on shutting down your engine and the as designed features.
     most manual transmissions had the  auto shutdown features and the additional feature of an override to run button  (switch manually held close ) to enable the driver to get the bus to a safe place or off the road etc..
     With the advent of automatics and auto trannys being installed in buses formerly being manual features had to change because most auto trannys do not like to be run from the wheels because of lubrication issues and maybe other items.   So other types of shutdown procedures had or should be adopted.   One system the Kysor system allows a double alarm such that when the first temp is reached   204 for example the system alarms   then when the next alarm goes off 209 the operator knows he has 30 seconds to run before the engine goes off.  he also has an override switch to keep the engine running but he needs to realize the potential damage to the equipment.
     other systems are in place with various transmissions.. Allison has some computer upshift patterns to protect the tranny in case of overspeeding.     
      Having said all this   I disabled the shutdown of my MCI 7 when the automatic was installed so that I would not have to worry about the bus pushing the tranny.   Now I do pay close attention to the alarms and check the engine temp religiously so that if I believe the temperature is higher than normal  I take defensive action  like  slowing down to get the temperature lower.   
         Generally a bus company would not disable a shutdown because of the variability of the drivers. SO in the final analysis  nothing is risk free so assess the risk and make your choices...   FWIW..
           Happy bussin    mike 

[Don4107]

If I was to eliminate the auto shut down, I would rewire the sensors to set off visual and audible alarms.  Not noticing sudden changes from coolant or oil loss could be $$$$.  Low oil and hi temp switches are pretty cheep and easy to wire up.

Don 4107

[Blacksheep]

Well Cliff, that's a silly question! With all the trouble I have had with electrical issues, YES of course I have disabled the shut down but let me also say that now that my issues are fixed once and for all, I WILL enable the shut down feature just as it was designed! It really is a good safety measure but it CAN be a PIA when something simple sets it off!

BS

[buswarrior]

Some confusion...the tell tales on the dash are a separate issue from the auto-shut down.

Properly working tell tales for the usual, hot engine, low oil pressure, no gen, are a desirable thing.

Having an automatic system that unilaterally decides for you, owner, financier, driver, and chief mechanic, that it is going to shut off RIGHT NOW....

I think we'll all get it pulled over and shut down in our own good time if the alarms go off, but making that choice according to the driving conditions.

Perhaps another vote on who has had an auto shut down, out on the road, at speed and doesn't want that to happen again, might be in order?

happy coaching!
buswarrior

[Blacksheep]

"who has had an auto shut down, out on the road, at speed and doesn't want that to happen again"


Ah YES, That would be ME!   

It ain"t fun either, let me tell you! 

BS

[FloridaCliff]

I had a fuel pressure sensor shut me down one time. actually the wire going to it.

The PO or someone wired it to a nut, ground = good, and it came off.

I was lucky that it was visible.

I plan on keeping the tell tales and a buzzer on them with a switch when I replace all the wires fore-aft.

Cliff

[Stan]

Automatic shutdowns are usually caused by high coolant temperature. When that happens, the temperature continues to rise, resulting in loss of coolant and a long wait before the engine can be restarted. Since day one, MCI offered an over ride switch as an option that could be hit immediately that the shut down occurred so that the driver could take corrective action. If it was a sudden coolant loss, get on the shoulder immediately. If it was just over working the engine on a long grade, drop a gear or two to increase fan speed and it goes back down very quickly. If necessary, get on the shoulder with the engine on high idle to bring the temperature down. The worst condition with an overheating engine is to stop coolant circulation.

My first MCI came with the over ride switch. I added one to both my later buses. Any inconvenience caused by a shutdown when your mind was on something else is quickly resolved with the over ride switch.

BTW: On all buses that I have worked on, the same high temperature switch that shut down the engine is the same switch that turned on the idiot light on the dash. Some engines have an oil pressure switch that turns on the idiot light at a higher pressure than the shutdown switch.

[JackConrad]

    When we re-wired our MC-8, we removed the auto shutdowns. We ADDED separate audible and visual alarms for low oil (Beeper), hot engine (Constant Tone) and low air (OEM Buzzer). We also added a Warning Test switch to test the function of all the warning devices. Momentarily activating this switch is part of our pre-start sequence.  We also have visual alarms for "non stopper" events such as low fuel, low tad axle air, no charge.  Jack

[FloridaCliff]

Jack was nice enough to give me a good look at his set up awhile back.

If you get a chance, take a look.  Very nice job Jack....

I plan on doing something vary similar.

That discussion really confirmed my plan to replace the wiring when I FINALLY get up to the finish in the drivers area.

Besides, in my GMC, that drivers control panel is getting moved above my head....Those of you who have to move your seat to work on these beasts, know what I mean...

Cliff

[Fredward]

I still have my oil and temp auto shut down installed. I watch the temperature gauge constantly and oil pressure gauge occasionally. I guess I could do without the high temp shut down; a buzzer would suffice. But a sudden loss of oil pressure could go unnoticed and it only takes a few seconds to destroy the engine.

Occasionally someone else drives and they may or may not be as vigilent about monitoring systems as I am.

Also on my 8V71 it has temp sensors on both sides and the high temp shutdown is only on the passenger side. I test it periodically by shorting it to the block.

Fred

[NJT 5573]

I can only speak about DDEC. If you disable the auto shutdown you have not changed much as far as your engine is concerned.

Instead of stopping in the middle of the road or RR/XX, DDEC resorts to a level 2 mode that cuts the fuel about 75% and allows the engine to continue running at about 25% power to allow the driver to get off the road, although very slowly. I picked up someones burned through A/C belt and cut the fan drive belt off last summer. With auto shutdown disabeled, first I got a yellow warning lite, 15 seconds later I got an additional red warning lite and the power dropped to almost nothing, just enough to let me get off the road and change the belt.

I would sell my bus before I would drive it with the auto shutdown turned on. The computer more than protects this engine in the secondary mode. Turning off the auto shutdown in no way will allow your engine to continue making useful power if DDEC reads a trouble code.

Turning off the auto shutdown will only allow the driver and not the computer to determine where in relation to traffic, and railroad tracks the bus stops.