6-71 Shutoff not working and engine wouldn't stop.

mung · September 14, 2014, 01:04:57 PM

OK, so I got far enough along with fixing the wiring to try to fire the bus up. And just as I had feared, it started just fine, what it wouldn't do was shut down. I had checked the solenoid before starting it and the switch was activating it, when I turned the stop/run switch on I could hear air releasing from the back. Now I did fix the broken bolt on the shut off plunger and so I think that something must have not gotten linked correctly when I was fixing the bolt, because it doesn't seem like it could have been anything else.

Since I had read on here that using the emergency shut off flapper would blow out the seals on the blower, I just pinched the fuel line and let it run out of fuel. I know it is going to be a PITA to prime it again, but I figured that was the best way to shut her down.

So how do I test the shut down plunger to make sure it is doing what it should do?

Thanks,
Vern

eagle19952 · September 14, 2014, 01:18:21 PM

learn where the shut off lever is on the governor.....then build a hook to employ it...and hang it in your engine bay....

then figure it out.

bevans6 · September 14, 2014, 01:35:59 PM

As said, learn how to put the rack in no-fuel before you start it again. If you're going to work on your stuff, that's the kind of entry level skill you need to have in your kit-bag before you start working on your stuff. Some old 6-71's had, I have learned, a separate air cylinder setup to put the rack in no-fuel on the rear of the head, the governor did not have the engine stop lever. You might have that setup. If it's air controlled, you may need air pressure above around 70 psi for it to work. Pinching the fuel line is a good emergency thought, way better than choking the air supply with the shut down flap which can suck the oil seals in the blower (so the old wives tale goes, but I kind of believe it). Putting a shut-off valve on the fuel line is a good idea but it can run for quite a long time on the fuel in the filters, and you would need to re-prime. You may need to re-prime anyway.

Brian

luvrbus · September 14, 2014, 02:12:11 PM

Your 6-71 have the shut down on the head or on top of the governor ? not real clear is it one of the old electric shut downs or air/electric just so we are all on the same page.

If electric you need power on the solenoid to stop the engine that is why they used a button or momentary switch

mung · September 14, 2014, 02:57:25 PM

I have the air controlled shut off on the right side of the head. The PPO (previous, previous owner) had fabbed up alternator brackets and 2 of them broke causing the bracket to break off the bolt on the right side of the shut off plunger. So, I only took the plunger assembly out far enough to easy out the broken bolt and put it all back together. The only thing I can figure is the fork that moves the fuel rail isn't in the right place now and I guess I need to take the top cover off and make sure it can move the rail.

So would my setup have another shut off on the governer side, which on my bus is on the left side. I can take pictures if need be.

Oh, and I had not planned to get into anything deep on the engine since I am 100% new at diesels. I was just trying to fix a broken bolt.

luvrbus · September 14, 2014, 04:09:35 PM

Photos would be nice but with the shutdown on the head it probably will be a single weight governor no shut off on those,pull the valve cover and check most of the time they won't start if out of place

eagle19952 · September 14, 2014, 04:13:23 PM

yup..pictures please

Edit:
Oh My....I just figured (learned) some of youse guyz have been around a long time....

here's a thought... what if one were to remove the street ell that the air line enters to the air piston/rod to rack and replaced that with a T, then fabbed a cap on the strait, then you would be able to insert manually a push rod into the no fuel position...with the cap off and an appropriate rod or T handled allen wrench type deal.
How the heck else would you shut that down with no air ? No electrics...?
If it were mine I'd be figuring something out...

mung · September 14, 2014, 04:52:37 PM

OK here are pictures of the air plunger thing and the govenator.

Now, don't bash me too much, but I am assuming that if I unscrew the four big handle things on top of the cover that is how I get it off so I can see if the rod for the shut off plunger is actually hitting the right place on the fuel rail?

Again, I am a diesel novice, I have changed out motors and trannies in cars, even fixed a valve that broke and went through a piston, so it isn't like I have never turned a wrench, I just have to learn about these diesels.

HB of CJ · September 14, 2014, 05:22:50 PM

If your mighty Detroit 671 is just idling, then using the emergency shut down should not hurt the engine one tiny bit. It is only when the engine is running wild at high or impossibly high rpm due to getting fuel or oil from somewhere it should not be will the emergency shut down lever possibly blow out the seals, but even then it may not.

However, resetting that emergency shut down flap thing will require two or more people, but usually is not a big deal. The long standing problem, however, may be that the manual ordinary fuel rack shutdown pull lever and the emergency shut down pull lever are side by side and look almost exactly the same. That can be a problem.

HB of CJ (old coot) (PEM me if 'ya wanna for an interesting story on this) How fast can a runaway rev? When do the valves float? Yikes! Very exciting for sure.

mung · September 14, 2014, 05:29:30 PM

My emergency shutdown isn't hard to reset, I tried it to see how it worked (not running though). I also know that the solenoid that works it from inside does not work so that is another thing to fix. That is on the intake to the blower and has a spring loaded cam that if you lift the solenoid plunger, it will drop down and close off the air. To reset, you just lift the plunger and lift the handle back to normal position, drop the plunger down and it holds it in place.

I don't think I have the manual shutdown on this motor. It is a 1953 so it is every early. Had a rebuild not many miles ago, so it does run very good.

bevans6 · September 14, 2014, 05:33:04 PM

my advice at this point is take the valve cover off and see what makes the injectors work, see the rack, watch what happens when you put it in no-fuel and start to enjoy the whole mechanical governator thing...

You'll see the injectors, and each one has a small toothed rack that is moved back and forth by the main fuel rail and it's little arms. Running the rack is adjusting all the little arms so they actuate the individual injector racks identically. When the injector racks are all the way towards the injector bodies they are in full fuel (no teeth showing on the little rack). When the injector racks are all the way back from the injector bodies they are in no-fuel. You'll see it pretty easy, it's not that much rocket science... You'll see the engine stop mechanism, how it pushes on the rack to move the injectors to the no-fuel position and what you need to do to make it happen.

Brian

eagle19952 · September 14, 2014, 05:34:56 PM

Confusion is bubbling here....I am asking about the engine/fuel shut down ie;rack no fuel position.
I assumed that this old beast had an atypical govenenor...it does not...

IS THIS WHAT YOU HAVE:.....or supposed to have....

gumpy · September 14, 2014, 05:45:25 PM

Umm, maybe I missed this, because I went through the replies pretty quickly, but by chance, was your coach already aired up when you started it? Because if it wasn't,
it's not going to shut off till you get air in the system.

Maybe it's working correctly.

mung · September 14, 2014, 05:52:28 PM

I believe that is exactly what I have. The air cylinder (number 5) had the right side bolt broken off at the head. I pulled the left side bolt and move the cylinder enough to get the drill onto the right side bolt to drill it and get the easy out in there and get the broken threads out, then bolted it back into place. The only thing I can figure is during that process, the push rod (number 4) came off of the injector control tube lever (number 2). So I think I need to take the cover off and make sure that in the bolted in position that the fork on the rod is pushing on the control tube lever.

That said, it would be nice to have a backup way of shutting her down besides either popping the intake flapper or cutting the fuel supply. Is there a way to modify this to have that backup?

Also what is the best priming setup for this motor, since I am going to have to do a big prime now. A fitting hooked up to the secondary filter's bleed valve with a pump and a hose that runs back to the tank? That is what my engineering brain wants to think would work, the pump would have to be a self priming pump or...if I put a boat priming bulb in line with it, that would allow me to suck the fuel through the pump, a glass filter would let me know when I had fuel flowing.

mung · September 14, 2014, 05:59:02 PM

Grumpy, it wasn't aired up before I started, but trust me, I kept trying it for the full half hour it took to get her to run out of fuel. The low air light (and my buzzer box that I built) were not on, bags were fully up, everything on the airside was running like it should, but it would not shut down. If I flipped the stop/run switch to off, nothing, when I flipped it back on, I heard air releasing from the back. I had good pressure, about 120 at the max. The only thing that makes sense is that the push rod is dislodged.

Silly me for thinking that there would be something engineered into the system to make sure that the rod would line up again. It sounds like it is not and the only way to reconnect it, is to take the cover off and make sure it is where it should be.