Old faithful ain't faithful anymore

fiddlearound · June 16, 2006, 07:50:12 AM

I've owned my MCI 8 with 6V92TA HT 740 for two years and it's always started on the first turn of the key. 'Till yesterday. It turns over but doen'st attempt to fire. Ran the generator and there is plenty of diesel. Checked the run switches in the back. Where should I start to find the trouble? I'm not much of a diesel mechanic and will probably have to get a mechanic over, but I would like to be able to follow what he's doing. Last ran about a month ago. Thanks, guys. Alton

TomC · June 16, 2006, 07:58:15 AM

If it is a mechanical engine, try starting it from the back. On the governor, the are two levers (on the top right of the engine as you face it). One for the throttle pedal and the other for the on/off air solenoid. When you activate the start from the back you should hear a small air release and the run lever on the governor should move into the run position. If not, maybe your electric over air solenoid has quit. You can remove that air piston and the governor lever will spring into run position. You'll then have to go into the back and manually shut off the engine until the solenoid has been repaired. Good Luck, TomC

gumpy · June 16, 2006, 08:01:47 AM

If you have diesel, air, and compression, it should run.

First thing to check is the stop/run switch in the rear. (http://www.gumpydog.com/bus/MC8_WIP/Run_Stop_Switch/run_stop_switch.htm)

If that's ok, my guess is your safety shutdown system is keeping the fuel shutdown solenoid activated. It's located on the top of the engine and is activated by one of the skinner valves on the forward bulkhead.
You can try starting from the rear console, and when you hit the switch, you should be able to see the solenoid back off and allow the fuel rack to open. You may have a bad oil pressure or temp sensor. Easiest way to find that is to disconnect each one at a time to see if it makes a difference.

Of course this is assuming you have air pressure in the bus (which would be pretty good if it's not been started for a month) because the shutdown requires air pressure to operate properly.

Where are you located?

fiddlearound · June 16, 2006, 09:20:07 AM

Thanks, guys for the quick response. I'm sure it's a mechanical motor. My problem with analysis is that the radiator is mounted facing out in the center of the rear. I see hardly any of the things you have mentioned. I will try the rear start and see what happens. Thanks again, Al

Busted Knuckle · June 16, 2006, 09:26:39 AM

Quote from: fiddlearound on June 16, 2006, 09:20:07 AM
Thanks, guys for the quick response. I'm sure it's a mechanical motor. My problem with analysis is that the radiator is mounted facing out in the center of the rear. I see hardly any of the things you have mentioned. I will try the rear start and see what happens. Thanks again, Al

I'm confused here you said you have an MCI 8 then you mention the radiator being in the center of the rear facing out? I ain't seen such. Can you post a picture? I'm having trouble figuring out how this is set up! BK

JackConrad · June 16, 2006, 10:52:10 AM

You said it turns over but does not fire. When cranking, do you see white smoke coming out the exhaust. If you do, I would check the emergency shut down solenoid. If no smoke, it sounds like a no fuel situation. Generator running off same tank means you have fuel in the tank, but does not mean fuel is getting to the injectors. Hope this helps, Jack

fiddlearound · June 17, 2006, 09:18:47 AM

I thought I might get a question about the radiator! I bought this coach already converted and this is how the previous owner plumbed everything. The 15kw Kubota genset is on the driver's side and is plumbed into the big radiator that is centered in the rear. The Webesto is plumbed on the curb side with the generator battery and the diesel and air filters. The electric fans are necessary when running the genny when the engine isn't running. (I also run them when under way to help cool the engine).

The good news is that it starts again. The rear start switch is a three-position toggle switch. Up is FRONT START, middle is OFF, and down is spring loaded REAR START. I tried to start by pushing down--nothing. Realized that I needed to turn the engine batt swith ON. Also decided that I should have the toggle switch on the dash ON. Tried the key switch and it started with one touch just as always. So, the rear switch should be in the OFF position instead of FRONT START? Tried again this morning and it started fine so I guess I had moved to toggle to the FRONT START instead of OFF. Does this sound right? So I guess I caused my own greavance. Thanks so much for the response and I have some more pictures of the engine area if requested. There is access from inside by removing the bed and insulated cover.
Alton Oh yeah, I'm in central Texas Gumpy. Just east of Austin.

Busted Knuckle · June 17, 2006, 01:11:01 PM

Ok Cool it was, well just I ain't seen that done before! Hey if it work we can't knock it! Now about all those coils of copper tubing hanging around ? Last time I saw that many coils of tubing Granddaddy was doing some "uh repairs" on the "Ol' cooker"also known as a still ! BK

gumpy · June 17, 2006, 03:30:15 PM

Glad you got it figured out. Sounds like your rear switch is wired backwards. When the switch is in the up (front) position, you should be able to start it from the front key switch. When it's in the middle (off) you should not be able to start it from the front. It shouldn't crank at all. The lower position is spring loaded and for starting from the rear. When you push it down, it should start and return to the off position. Yes, you need the batteries on and the front switch on.

Common mistake, but maybe exasperated by your particular wiring on that switch.

gus · June 18, 2006, 01:49:45 PM

Agree with gump, otherwise there is no need for the Front position?

GMCs have one spring loaded Start switch in the rear. When it is Off the front Start switch works. Push it up with the front Run switch On and it will start.

There is a separate switch that makes it impossible to start from anywhere, I think it is called the Starter Cutoff Switch.

Apparently MCI has combined these two?

fiddlearound · June 18, 2006, 07:44:59 PM

BK, them there copper tubes are for making bio-vegi-diesel, don't you know!! Shouldn't have to heat it to get it to burn, huh?

I'm wondering if there is something that can corrode in that switch box at the back? This happened again about a year ago, but I had assumed at that time that my brother had moved the switch position. I moved the toggle and it started just like this time. Maybe a fuse or something? Alton