Farmall MD, SMD, SMDTA, 400 and 450 change to direct start?

Question for the forum:

Could the gas start diesels be turned into direct start diesels with a bigger/more powerful starter and a 12 volts system?

I'm assuming that it would start hard without any glow plugs, but I think you could rig an intake air heater (maybe).

The real question, what would this do to the head? Would the lack of warming up on gas hurt the head?

There is no good way to do it. I have pull started my MD when I had a bad condenser in the Ignition.
Dragging it several hundred feet with it spinning much faster than a starter would do it, makes me a believer in its original system. It is not a very high compression diesel, and without glow plugs, or an intake heater equal to at least twice that found on the Continental 350D, it would not start.
It would not affect the engine head cracking issue if warmed up easily, and cooled down for 3 to 4 minutes.
Again, I believe they are one of the easiest starting diesels in below zero weather because they start on low compression gas. (you can crank start them! Jim

it's got 17.45 to 1 which is about the same as my
cummins diesel a little higher you would think a 450
would crank right on up with a powerful starter. a
cummins starter might be right for it

A few thoughts:

1 - A cold IHC gas-start diesel will fire if it's spun up fast enough. Key is to get the RPM's up into the mid/high end of the governed range. A suitably powerful starter to spin the engine to 1,200 RPM or higher could work. But it would have to be a BIG honkin' starter. And it would of course would need an equally big bank of batteries to feed. Probably not practical. (Incidentally the original MD thru 450 starter/electrical system is 12 volt...)

2 - A manifold heater could probably be rigged. But to be effective it would require the heating elements be located as close a possible to the intake valves. Ie. a pair of heaters, one at the end of each manifold runner. Again it would be complicated, expensive and require additional battery capacity to supply.

3 - Heating/cracking of the head should NOT be an issue when direct starting, so long as the engine was allowed to warm up a few minutes after starting. Reason: there's LESS heat absorbed into the head when idling unloaded on diesel than when running on gas. Ie. the engine will be warmed up more gently when started directly on diesel.

---

Bottom line: Direct starting could probably be accomplished. But it would be expensive, and probably no more reliable than the original "start on gas" system.

Thanks for the replies.

I'm not currently planning to do this, I'm just thinking out loud so to speak and wondering if anyone else has thought the same thing.

I was thinking that if someone need to cold start the engine and it was in the shed/barn. You could probably use a 220 volt motor, possibly hooked up to the pto??? to turn the motor up to speed and only use the battery start once it is already warmed up.

The air intake could also be plug in to 110 volt or whatever instead of running off the battery.

Again just thinking outloud and looking for some feedback on whether it would work or not.

My TD6 would fire right up on diesel if the temperature was about 70 or higher. Also had no problem starting if it had been running within about a half hour when the temps were above zero. It had the original type starter and battery.

They won't start if a common coolant block heater is used?

The point of glow plugs or intake heater is to get the air/fuel charge warm enough to combust at a low RPM.

Block heater just doesn't cut it as far as that goes.

It is a precombustion chamber engine, low pressure injection nozzles and it requires a lot of heat in pre cup area to fire up. A glow plug in each cup like 282 would work but would require better cranking speed for good starts. Some refer to the energy cell type systems other engines used (the continental in the 350 uses that) and say they start direct so why won't these pre cup engines . Well, there is a lot of difference from pre cup to energy cell. Once a pre cup engine gets going and warmed it has great turbulence created which is not so during cranking speeds. Also, notice the light construction of block, crankshafts etc on 282 etc and even diesels used in auto years ago. Reason, pre cup engines don't have the violent combustion directly on the piston , rod and crank like the open chamber engines do. The original M D style engine was way over built down below in comparison. Also, engine was originally designed so it could be started by hand crank, reason for design of starting on gasoline.

i got a b450 diesel that is supposed to start with glow plugs havent tried to start it yet ,just got tractor, been sitting for years got muddobbers in exhaust and probably engine etc.

The newer grid heater's that diesels use would work I would think. You would just have to fab it into your intake some place. Like the one on my 6.7 cummins, the thing starts like a gas engine even in sub zero temps.

That's what I was thinking, to use a grid heater in the intake. There has to be a reason why truck engines are moving away from glow plugs. If I had the time and $$$ I might try to rig something up, but too many other projects and not enough time.

Like I said, the reason they went away from glow plugs is they are direct injection( open chamber) engines weather they use mechanical injection pumps , cam operated or electrial controlled. High pressure, multi hole injection nozzles injected directly into bowl on piston. Whole different animal.

Thanks mkirsch,

That explains lots.

One thing I have to wonder...

The D361/D407, and D414/D436/D466 series engines are direct start with no "energy cells," no "glow plugs," and no "grid heaters."

Granted, they don't start that great in the cold without block heat, but that's all they need... Just simple block heat.

How do these 30-40 year old engines manage to start, run, and survive when modern diesels need glow plugs and grid heaters?