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Bus just died...everything David G 8-19-02  
Pulled off of I35 to fuel stop. Making right hand turn, electric panel door under dash heater flopped open and hit floor. Everything died, engine and all electric. 1975 Crown, 6N71 Detroit Diesel, 5 spd. Volt meter dropped below 10 and wiggled when tried different switches. Searched for trouble about 10 min. Found one huge fuse in engine compartment, pulled it out &'s OK. Reinserted the fuse and all OK...everything normal, starts and finish trip home 2hrs.
Any idea what happened or what I should look for? I did encounter a very severe RR crossing several hours earlier ( stopped & started after that ).
I thought diesels did not need any electric to continue running?? What would kill all?
Re: Bus just died...everything Joe 8-19-02  
Dave, there are many things that could cause your problem from a battery all the way up. First check your batteries and all the cables. Check the cable on the starter as well as the grounds. Your engine will run without a battery, but the shutoff is probably air controlled. When the power is cut off from the air solenoid, the air pressure is allowed to shut your engine down. If not it has an electric shutoff and kills the engine when the power is cut.
Re: Bus just died...everything Bob Mohar 8-19-02  
Had similar situation, took long time to locate problem, which was loose connection at solenoid and bad solenoid. Check voltages across solenoids should be <.3 volts, look for loose connections. good luck, mine died rollin down the road in Mexico!
Re: Bus just died...everything Sam Watson 8-19-02  
Seems the main power fuse was jarred loose by the impact of the RR crossing. Diesels have an electrical solenoid valve in the fuel line between the fuel supply and the injector pump, that's how you turn a diesel off; you turn its fuel supply off.
Re: Bus just died...everything Joe 8-19-02  
Sam, his 671 has a control rack that shuts the engine down by moving the control rack beyond the idle position. It is totally manual.
Re: Bus just died...everything David G 8-20-02  
So help me out here guys. How does this manual shut off work? When I turn the key switch off...what happens to cause the engine to quit? Something must happen to shut off air or fuel. Some electrically actuated selonoid? I suppose I could pull the big fuse in the engine compartment while the engine is runnig and see what happens.
Also, there seems to be a switch that ensures that the transmission is in nutral before the starter will engage the engine. Where might that be?
Re: Bus just died...everything Sam Watson 8-20-02  
Maual shut off makes the fact that his engine died at loss of electrical power even more mysterious, eh what?
Re: Bus just died...everything Joe 8-20-02  
Read my first post and it tells about your shut off.
Re: Bus just died...everything David G 8-21-02  
OK, Thanks Joe. I think I understand. If I lose electric power to the key switch ( I lost power to everything ) it is just as if I had turned the switch off. My problem is up stream. Cables & batteries seem OK. This incident coincided with the door holding a bunch of electric stuff flopping open and hitting the floor.
Do you know if there are any circuit breaker type devices that would reset themselves after 10 min or so? Like a thermal protection device?
Re: Bus just died...everything Joe 8-21-02  
There usually is a master breaker on those older busses. It could be tricky to find, but it looks round, about 2 1/2 inches across. Usually these are mounted on the frame close to the batteries. They will self reset when they cool down. You can look near the engine for a set of controls to start and run the engine from the rear. These controls are there for the service person to be able to start the engine without going up front. That is why it has a neutral safety switch. Also there usually is an override for the engine shut down that you may find. This would be located at the top of the governor near the valve cover. Look at the blower and follow the piece that goes up to the head and the shut off will be on top of that.
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