hello all,
So my MC9 will not start. I have checked fuel lines and I can't seem to find anything leaking. it cranks and I get the white cloud off death but it wont fire. any thoughts. Ive checked the emergency shut off and still nothing. I had parked the bus closer to the house so I can gut it and put the floor in. but now it's time to move it back. she just wont start. I have tried the block heater and read the troubleshooting posts on here for weeks now. someone please help! :-[ I'm pretty sure it's something small and I have over looked. the tank is about halfway full.
I look forward to hearing from you all..
James
Make sure the block heater actually working. Is the engine warm when you try? Is it spin ING over normally or slow? A decent 8-71 will start in about 1/4 revolution.
You can hear the block heater when it is working I see in your area it is in the 30's they need a little help that cold when they are weak
I left the block heater on (working) for about 6 hours today. it was warm when it made complete rotations. i'm going to try switching out the fuel filters tomorrow.
It needs priming then if the block is warm and the engine is spinning
Suppose to be 65 in your neighbor hood this weekend. I live in Evansville Ind and pass thru on way to Nashville every couple weeks. In Frostproof Fl now for a while. Ck make sure your rear switch is in correct position also if your trying to start from rear make sure front switch is on. Your shut off cyl could be stuck out also--to try it take phillips screw out one side and turn sideways. You can shut off by hand if needed. Fuel is first thought then elect then shut down cyl. Are you military? Bob
Bob,
Yes I am Military. I'm a Former Marine. I figured it was something simple. I want to replace the fuel filters so now i just have to a find a place that has them. good thing there is a truck stop at exit 1. they usually have what I need.
Just a hunch here but does the mighty Detroit sound quite different when it is spinning? How fast is it spinning? It might take two folks to re set that flapper.
Quote from: HB of CJ on February 25, 2016, 05:40:55 PM
Just a hunch here but does the might Detroit sound quite different when it is spinning? How fast is it spinning? It might take two folks to re set that flapper.
Ditto. Flapper. My bet's on the flapper.
Mine wouldn't start a month ago, just wire smoke. I find the fuel shut of valve stuck. I didn't open it up, I just tapped on it with a wrench while cranking it over and it fired right up. I need to open it up and clean it out so it doesn't do that again. Check that....
Eric
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Not much to these engines. Air plus fuel equals bangity bangity.
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In my experience lots of white smoke equals fuel but no air. I had the emergency stop flap on top of the blower self-deploy twice on my natural 8V-71 and had exactly this symptom.
Brian
Generally black smoke is excessive fuel, lack of air. White smoke is plenty of air and lack of fuel. Blue and grey wet smoke are bad! Lol
But that's just my experience.
FWIW
Eric
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I don't for sure if it is the emergency shutoff flap, but I would certainly say that that has to be the first thing to disqualify.
What if he has no emergency stop not all 71 series were equipped with the emergency stop
Yep. later 71 series engines did not have that flapper? DDEC engines? That flapper can cause major problems. Years ago we burned the roofs off of three (3) very expensive homes due to a series of very unfortunate events starting with the first due engine accidentally having that pesky 8V71N flapper ... flap! Yikes! :(
If he does not have a flapper, then it is disqualified. If one is not sure whether they have one or not, this would be an excellent time to learn.
Clarkesville is FT.Campbell=Should be some one in motor pool that could help. Do follow thru with solution as it may help someone else. Bob
Clifford, in 1980 MCI's had the flapper, and a special switch on the dash with a red air-craft style cover you had to lift to operate. Mine still has the switch... ;D
Brian
I am just pulling Lin's chain Brian,I'll dig up the old service bulletin from DD on what year they wanted those removed. Fwiw 92 series had those in some applications.They were always a problem mostly because of maintenance issues
so it started. it was the flapper. i hate and love that thing at the same time. shes running now.
thanks everyone.
When my 8V-71 was turbocharged by Don Fairchild, he removed the flapper since he changed the injectors to 7G75 which are spring loaded. This left a wire and switch not used on the dash that made for the perfect spot for my misters. Good Luck, TomC
Quote from: carneybus on February 27, 2016, 08:29:49 AM
so it started. it was the flapper. i hate and love that thing at the same time. shes running now.
thanks everyone.
I have the hate relationship only, those things are a problem the little seals and shaft gets ware and dirt is sucked into the engine then the latch gets ware and they self deploy all because lack of maintenance, they are a real PITA.I see a lot of those the owners solve the problem with zip ties and bailing wire ???
When I got our bus, he flapper did not work. After learning that is was supposed it work and could be very important, I searched out the wires and put a protected switch on the dash. I really should give it a test since I haven't tried it in quite a long time. Anyway, now that it's there, I question whether I would ever be brave enough to use it. If the engine had gone rogue, I would hope that I could shut it down by cutting off the fuel. Because of that nasty belt on the MCI, I keep a stick around for that purpose. I think that I could only get myself to hit that button if it was a desperate last resort.
QuoteIf the engine had gone rogue, I would hope that I could shut it down by cutting off the fuel.
It is my understanding that traditionally when a diesel goes "rogue" that it is because oil from a blown turbo? In which case shutting off the fuel would not solve the problem. Which brings us back to the flap, or some other means of starving the engine of combustion air.
Please correct me if I'm wrong.
Solardude.
Quote from: solardude on February 27, 2016, 08:32:05 PM... the flap, or some other means of starving the engine of combustion air.
Please correct me if I'm wrong. Solardude.
Not a "correction", SD, but the flap/emergency-shut-off-valve IS the means of starving the engine of combustion air (at least in theory). Look at the archives and you'll read about times when people have had to deploy it and had results like the engine "swallowed" the entire valve (and continued to run away, of course) or the vacuum ruptured the blower seals, etc. When people talk about a love-hate relationship with the flap valve, they're not joking.
You are correct in that one cause of engine run-away is from a serious oil leak upstream of the intake. On these DD two strokes the worrisome issue to Detroit was a sticking injector holding the rack open, causing not an oil run-away but a "stuck throttle" situation which in a bus could be a serious safety issue. They put the kill switch on the dash under a big red safety cover (MCI's at least) so the driver could kill the engine. Don't forget that if an injector sticks open the rack is no longer under control of the governor and so it can really overspeed and cause a lot of damage. Later in the game (sometime after 1980 I guess) they redesigned the control rack tube fingers from a fixed design to a spring-loaded design so that one stuck injector could not hold the rest of the injectors open. At that point they wanted the air flap gone because it was no longer needed for stuck injectors and because to would self-deploy and cause problems. Mine did it twice, causing a no-start only, but if it had done it at speed on a hill I would have been some upset!
Brian
Besides killing a run away engine, the flapper valve is a good one for use when parking the bus for a long time un attended. The flapper can be an effective theft protection. Good Luck, TomC
My 1980 Prevost still has one as well and the red flip up cover over the toggle. Right beside the steering wheel.
Ryan.
I've thought about adding something to stop a runaway engine (mine's blessed/cursed with electronica), and I have an additional toggle switch for directly turning on my Jakes manually - someone suggested that it may be enough to stop a runaway, but it just growls the engine down at idle without actually stalling it. I think a CO2 injection system could be effective: it won't harm anything else, unlike a flapper's collateral damage. Has anyone here got a CO2 setup for this purpose? Is this a silly idea, or is it something worth thinking about?
John
Your mighty Detroit would NEVER run wild? It would not dare! You have a Crown Supercoach? Crowns Forever! :) :) :)
Yes, the choice whether or not to use the flap may just be the hope that it will only do serious damage and avoid complete destruction. That's why a called it a desperate last resort on a true runaway.
Any diesel engine will runaway under the right circumstances
Mine self deployed at 70mph on the interstate. And it sucked about a gallon of oil from the blower into the airbox in the 1/2 mile as I pulled over. If I had thrown the clutch in right away it wouldn't have sucked so much but I first thought out of fuel the way it lost power so I switched to the reserve tank and stayed on it for ten or fifteen seconds before looking in the mirror and seeing black smoke billowing across the highway. I left a straight solid line of oil on the interstate as far as I could see that came from the air box drain. Luckily my seals in the blower were only a few months old and have not yet shown any signs that they were damaged. Biggest problem was it collapsed my intake hose. Its happened a few time on me since. That day I secured it with electrical tape and thought that would keep it up but like a week later the tape got hot and stretched allowing it to deploy. Now it's zip tied. 3751 mounts the plunger vertical and vibration can pop it out of the locked position. I thought my engine was dead by the amount of oil that poured from the airbox. But nope I just let it drain and added a gallon to the engine, wedged the intake hose into a non collapsed position and wrapped it with duct tape and away I went.
Halon might be considered also.
Halon would be a great choice - clean, pure gas, wouldn't harm anything in the engine at all - but manufacture of halon has been banned since 1989.
Brian
I doubt that I will ever do anything to change the flapper system on this engine, but since people are floating ideas on alternate shutdown systems like CO2 and Halon, it brought a question to mind. What would happen if one had a way to divert exhaust into the air intake? Would that shut the engine down without creating other problems?
Lin,
I think what would happen is your bus would then run in perpetual free energy motion!!! You should patent that idea!!!!
I thought that Apple got the patent for perpetual motion along with the one for the rectangle.
I won't mention his name, I know this guy that got a bargain on a starter (25 bucks) some how with the left handed rotation starter he bought for a right handed engine he got his 8v71 started backwards.He called me in a panic mode by the time I got there the 8v71 had the whole neighborhood smoked up and was still chugging a long ,it took a while to get it shut down even with flapper closed.I LMAO he didn't think it was all that funny till a few hours later
That's funny Clifford :)
Blower drive shaft?