M923A2 Cold Start

[wbread99]

So played and posted a "diesel cold start" with my A2 the other day and it truly didn't want to go at 2 below. Did with either shots.

Question: do we have a small generator that makes power for 12V dc for the batteries, 120V for the block heater, and hot water to warm up water jackets?

 

[sandcobra164]

2 below makes many things not want to start. I'd imagine a small 3kw generator coupled with a regular battery charger and a block heater would do wonders if left hooked to the truck for about 3 or 4 hours prior to use would do wonders. You can also find 24 volt battery chargers and wire up a Nato Slave adapter to plug right into the passenger side of the cab to the "Slave Port" that would simplify your task. If use a regular battery charger, you would have to lift the seat, disconnect from the truck and wire them in parallel in order to use a regular battery charger. That would be rather time consuming in regular weather and a monumental pain the tail in -2.

 

[74M35A2]

I make small portable hand carry Honda powered gasoline powered 12v and 24v generators. The market has 120v generators covered. There are also diesel fuel fired coolant heaters.

But, your truck should have started. I did an -11F cold start with ether on my A2 and it started well. If your fuel system is air leak free, your batteries are less than 5 years old and test at or above their CCA rating, and your ether system has fluid and is known working properly (it only sprays while cranking, hold button down for 3 seconds and release, repeat if need be), it should not need any of the forementioned external starting aids.

May be lower cost and right direction to modernize the high current system such as starter, alternator, batteries, and update the soft fuel lines and overflow valve in the injection pump if you have not done so yet. Stock alternators are terrible at best, modern gear reduction starters pull 50 amps less current and have higher cold cranking speeds, and the soft fuel lines and overflow valve are known issues to need service after decades of use.

 

[Smckerigan]

It's been cold here in Nebraska, I went out the other day and it was - 10 out and my A2 would crank over good but just to cold out so I used a shot of ether and she fired up.

 

[Tinstar]

Replaced POS original alternator with 100A Delco-Remy bought from SS member 74M35A2.
Batterys are healthier since they are recharged faster and more complete than the original 60A could ever do.

Now after sitting for a few days I turn on battery switch and the needle is just Touching the green zone.
Not in the lower yellow anymore.

Cranked right up when it was -1 the other night.
Took a few seconds for her to clear her throat.


Best thing Ive done is replace the stock alternator.
Of course I didn't have a choice since the original fried itself and the PCB & ABS module.

 

[Nomadic]

I'm new to diesels and sub-zero temps. Why does an engine fail to fire w/out either?

 

[simp5782]

I'm new to diesels and sub-zero temps. Why does an engine fail to fire w/out either?

No glow plugs. It is just easier to spray them with a small burst of ether so they don't struggle.

Sent from my SM-G860P using Tapatalk

 

[Jason O]

I'm new to diesels and sub-zero temps. Why does an engine fail to fire w/out either?

A diesel relies on heat, created during the compression stroke, to ignite the fuel/air mixture injected into the cylinder. In extreme cold temps, there is less heat to begin with in the engine, AND the engine will likely be cranking slower, resulting in less heat being generated during compression, so the fuel may not ignite without some help.

The starting fluid is much more volatile and will ignite at a lower temp/pressure inside the cylinder.

 

[Tinstar]

I'm new to diesels and sub-zero temps. Why does an engine fail to fire w/out either?

Diesels use high compression to create heat for combustion.
Glow plugs, like in the CUCVs, heat up the cylinder chamber and makes this happen easier when extremely cold.
Some Engines, like ones in the M939 series, without GPs use highly volatile Ether to help the diesel combust until the combustion becomes self-sustaining.

Thats why batterys are so important.
The engine has to spin fast enough to get that compressed mix to fire.
Slow crank speed will not start a diesel, unless ether is introduced. Even then not always.

There's s better explanation I'm sure, but that's my understanding of it.

 

[WYomer]

Mine gets hard to start at the 0F mark but a burst of either and a few cranks help get it moving. I just started it at -49F couple weeks ago.....poor girl if I didn't have to take a snowed in neighbor to the hospital I wouldn't have started her.

Honestly she starts its other issues I've found in subzero temps that have worried me more.

 

[Tinstar]

-49.....??!!

You Win

 

[74M35A2]

We test starters all the time at -40F, and one time I put an open top container of diesel 15W-40 oil in the test cell also. After sitting overnight, I turned the container over, and the oil did not even run down the edge of the jar. It completely stayed as a solid block in the container, without even a single drip or run down the edge. Next day I went and put an oil heater in my 8.3, as the pan does already have the port for it. Sorry I don't have the p/n or thread size remembered (ie don't ask). A block heater does not warm pan oil, at all.

 

[WYomer]

-49.....??!!

You Win

Wish I didn't. Found out a few days later during that my neighbor froze to death in his house too. Just recovered his last two horses Sunday, took about 10 people all day to do it.

 

[NEIOWA]

Has been above freezing for 4days. 35F today. M925A0 cranks good but no fire. Put block heater on for a couple hours and fires right up. (2008 M916A3 and 2001 IH DT530 sitting next to her start right up at 15F with not aids). I'm just not so impressed with cold weather starting of the M925.

As I recall when on active duty we just left M923A1 idle all night when below freezing.

 

[wbread99]

Sorry folks, I guess I could have been more clear in the original post. The truck did start, but only with ether shots. Would shoot it, burn through the shot, and repeat. Took after 3rd time.

Here is the part 1 youtube: https://www.youtube.com/watch?v=9BXgS8x1l08 Theres a part two of me in the pissed off, but running truck.

I saw a piece of AGE at one time that provided battery power to the batteries, but also used its engine's hot water to circulate water into the cooling system through some QD fittings. My generator has both 120V and 12 V for the block heater and batteries (individually) but its air cooled.

Just wondered if someone here had built a hand carried or wagon mounted rig that could do the same thing, but capture cooling water to provide hot coolant for the engine. In my head, I envision a small water cooled motorcycle engine driving a 24V alternator on a wagon, providing power for the batteries and hot water for the truck.

You guys going to leave me to build it?

I make small portable hand carry Honda powered gasoline powered 12v and 24v generators. The market has 120v generators covered. There are also diesel fuel fired coolant heaters.

But, your truck should have started. I did an -11F cold start with ether on my A2 and it started well. If your fuel system is air leak free, your batteries are less than 5 years old and test at or above their CCA rating, and your ether system has fluid and is known working properly (it only sprays while cranking, hold button down for 3 seconds and release, repeat if need be), it should not need any of the forementioned external starting aids.

May be lower cost and right direction to modernize the high current system such as starter, alternator, batteries, and update the soft fuel lines and overflow valve in the injection pump if you have not done so yet. Stock alternators are terrible at best, modern gear reduction starters pull 50 amps less current and have higher cold cranking speeds, and the soft fuel lines and overflow valve are known issues to need service after decades of use.

 

[rosco]

There's nothing like a block heater & a heating pad on your oil pan. That's what lends itself to a long dependable life, and you won't need that either. The rule is, pull the dip stick..... Oil should be warm enough to drip off. If you try to do a cold start & it doesn't start, then your batteries will be seriously discharged & are susceptable to freezing & destruction. A fully charged battery won't freeze. Best bet is to do the homework & put in the heaters & keep truck where you can plug it in.

 

[71DeuceAK]

Threads like this always fascinate me, as someone who might have a 250 Cummins powered M923 in Fairbanks in a couple winters. Of course, block heater, heating pad on the oil pan, etc. but hearing people's success or failure stories always intrigues me.

 

[lindsey97]

Diesel flash point: 126 deg F

Diesel autoignition temperature: 493 deg F

The flash point is the lowest temperature at which vapours of a volatile material will ignite, when given an ignition source.

The flash point may sometimes be confused with the autoignition temperature, which is the temperature at which the vapor ignites spontaneously without an ignition source. The fire point is the lowest temperature at which the vapor will keep burning after being ignited and the ignition source removed. The fire point is higher than the flash point, because at the flash point the vapor may be reliably expected to cease burning when the ignition source is removed. Neither flash point nor fire point depends directly on the ignition source temperature, but it may be understood that ignition source temperature will be considerably higher than either the flash or fire point.

In other words, you have to spin the engine fast enough, to smash the air/fuel mixture to cause instability and friction to auto ignite at 493 F. That is a pretty tall order when the fuel in the tank is cold, the whole truck is cold, and your oil is thick as molasses which is harder to pump up, which slows your starter down.

Ether will ignite pretty much at any temperature, and is extremely dangerous. Old school folks with big fuzzy ones use ether to mount tires on rims(seat bead) because of it's rapid expansion rate when incurring temperature changes.

This is why a coolant block heater works so well. Plug it in overnight, and it heats your coolant, which in turn heats up that big iron engine. Heat goes up, and the injectors are in the head, and they have fuel in them. So if this tiny amount of fuel is brought up in temperature from 0 deg F, to say 70 deg F, your truck will start in literally 2 seconds, thus saving wear on your starter, and batteries.

They also make electric blankets for your batteries, and for your on-board air tanks.

Another topic which I have yet to see discussed here when the subject of getting a cold truck started, is the subject of air systems(read brakes) and fuel filters. So let's say you get your truck started and it's 20 deg F outside. Good deal, it's running, you are building air, and for some reason that tiny bit of moisture in your air system, and the water in your fuel filter isn't frozen. So you proceed to drive, brakes are working, and you get up to 60 mph for several miles. Then the water in your brake system freezes, due to a 60 mph wind chill from underneath the truck, and you lose ability to build air and/or apply air to stop. Then what? Or maybe your fuel filter freezes up due to wind chill at 60 mph, leaving you with a 22k lbs. boat anchor in the middle of a state highway.

I have had trucks before I had military trucks, and have had all of the above happen at one time or another. If it's much below 32 deg F, my dump trucks stay home because of safety reasons and inability to safely operate in inclement weather. Maintain your trucks, safety is paramount whether it is a hobby or a livelihood.

 

[porkysplace]

Threads like this always fascinate me, as someone who might have a 250 Cummins powered M923 in Fairbanks in a couple winters. Of course, block heater, heating pad on the oil pan, etc. but hearing people's success or failure stories always intrigues me.

You may also want to look at battery heating pads or blankets.
https://www.hotstart.com/en/home/products/battery-wraps-silicone-pads/

 

[Jbulach]

...I saw a piece of AGE at one time that provided battery power to the batteries, but also used its engine's hot water to circulate water into the cooling system through some QD fittings. My generator has both 120V and 12 V for the block heater and batteries (individually) but its air cooled.

Just wondered if someone here had built a hand carried or wagon mounted rig that could do the same thing, but capture cooling water to provide hot coolant for the engine. In my head, I envision a small water cooled motorcycle engine driving a 24V alternator on a wagon, providing power for the batteries and hot water for the truck.

You guys going to leave me to build it?

You might look into small outboard motors. I think the are water cooled?