Not running, new to me MT372

[CausticUrbanCoast]

Sorry to ask the default question; new or new and fully charged? (Some places are not great on maintaining batteries).

 

[Lawson Farms]

I didn't load test it when I installed it, but i did check it with volt meter at 12.6 volts. I also had a charger hooked up while i was cranking and cranking so i wouldn't wear it down.

 

[CausticUrbanCoast]

Hmm.

My suggestion while you wait for your battery to charge would be to check your injector nozzles.

That they started flowing is a good sign! May save you from trying to find a rebuild kit. You could have had some luck and they cleared themselves out.

 

[Ilikeurtractor]

One of the best devices for troubleshooting electrical on vehicles is a DC amp clamp which are cheap enough now that everybody should have one just like a standard multi-meter or one that has a DC clamp integrated into it. Glow plugs typically pull around 10A each at 10VDC. You can wire them to a dedicated switch but the risk of burning them up increases since going through the indicator drops a couple volts off and the glow plugs designed for your engine are rated for around 10 VDC, not 12. The reason for this is because the glow plugs should have power to them while the engine is cranking and because of the power draw during starting the system voltage usually drops to around 10VDC.

Remember if you're going to spray anything combustible into the intake of a diesel you really should disconnect the glow plugs or other intake type heating devices as they can and usually will ignite the mixture upon contact and independently of piston position. My experience with the 2-cylinder Mitsubishi's is they don't play well with any type of starting aids sprayed into the intake even if the glow plugs are disabled. These engines are capable of starting in cold weather (down to even 0 deg F) with only glow plugs and the electrical system in good condition including a high capacity electrical supply (i.e. full battery + jumped from another vehicle if needed) so having to use starting fluids means the engine is suffering from other problems which usually is loss of cylinder containment (low compression) due to poor ring sealing in the cylinder.

I have yet to see a pump that required a "rebuild" for these engines to run. My pool of knowledge is from about a dozen or so of these engines in various stages of condition over the past decade.

 

[CausticUrbanCoast]

Interesting.

My Mitsubishi does not activate the glow plugs while starting, my wiring diagrams do not indicate it should be either. Feature of the larger tractors maybe?

Correct to your comment, injector rebuilds are typically only needed when nothing flows. This means either a diaphragm or part of the can is not functioning properly. It is not common on a regularly used tractor, but on one sitting for a while it does happen.

That he now has fuel moving is a good sign it will not need one.

It seems like the new battery might still be too low, or it is possible the injector nozzles are not all clear.

 

[Ilikeurtractor]

My Mitsubishi does not activate the glow plugs while starting, my wiring diagrams do not indicate it should be either. Feature of the larger tractors maybe?

No. Glow plugs should be active on all diesels during cranking, especially the smaller ones. My Satoh S373D wiring diagram does not indicate the glow plugs are active when the starter is engaged but it is wired that way on the tractor and I believe the wiring to be original factory wiring. So a discrepancy in the schematic exists. Sometimes if it's cold enough I'll turn the switch back to the glow plug position quickly after it starts (after glow) to maintain combustion until the chamber areas warm up enough to sustain combustion which usually is only a few seconds of run time. On smaller displacement engines with swirl chamber designs (and this becomes more of a problem as the number of cylinders increases for the same displacement) the metal surface area of the combustion area is relatively high compared to the combustion volume so the problem of heat loss into the metal is greater and results in more difficulty in starting.

 

[Lawson Farms]

So last night I did get it to finally crank. Before I did that I pulled the glow plugs to test them. I did have continuity, but really low resistance. What I've read is that i should have less than 1 ohm of resistance. My meter leads are about 0.6. Testing the plugs showed between 0.6 and 0.7.

I then hooked a small alligator clip from the negative post of the batter to the nut on the g.p. i then touched the top of the plug to the positive terminal to see if the end would glow. I only held it long enough to put off a small bit of smoke cause i didn't want to burn through the small wire that had the alligator clip in it.

I did all this after seeing that my dash indicator would no longer glow red.

I reinstalled the GPs and wires, and cranked till I finally had fuel dripping at the injectors and now black smoke out of the exhaust. Since the indicator didn't glow red for the GPs, I tried to jumper them from the battery. So I used one separate wire from the +battery lead to the top of each plug. These were probably 20 or 22ga wires with small alligator clips. I would attach them and start counting, then start to crank the engine and pull them off manually. I did finally get it to crank, but burned the wires off the alligator clips in the process of about 25 seconds of pre heating. I only let it run for less than 60 seconds because the radiator is empty. After that I attached all the air intake equipment and tried to start again. It would not start, but I had no glow plugs. And then I tested volts to the plugs, and it was only 2 or 3 volts.

So my next step I guess I'd to either fix the glow plug circuit, or just rig a quick switch for the GPs until I can tackle the "why is the radiator empty" problem. I don't know if it's thermostat or water pump or just previous owner issues.

 

[CausticUrbanCoast]

You are getting closer, sounds like your ignition switch may not be functioning properly. Perhaps the contacts are oxidized too much.

The wires from the plugs to the ignition switch are pretty straight forward to test continuity.

My tractor would have to run for a few minutes before I can shut it off and restart without using the glow circuit again.

I will say that seems a very long time to energize your glow plugs. Not sure where the rule of 10 came to me on glow plugs (it was definitely when I was a kid), but it goes: 10 seconds glow and then try to start, if it does not take 10 seconds more glow and it will start.

Has never failed when things are working and it's a reasonable temperature out. Not sure if it is just old farmers trying to prolong glowplug life, or where the 10 second thing came from.

 

[CausticUrbanCoast]

There is this interesting comment from Mitsubishi on their glow circuit.

I have yet to figure out which wires are the heat and timer wires on mine- either that or they are missing.

 

[Lawson Farms]

[I finally got it cranked and running. Water pump Is leaking, so that's my next task.




QUOTE=CausticUrbanCoast;5410930]There is this interesting comment from Mitsubishi on their glow circuit.

I have yet to figure out which wires are the heat and timer wires on mine- either that or they are missing. View attachment 602235[/QUOTE]