Farmall MD ignition cut-out on Diesel

Hattrick · Dec 13, 2012

I have my MD running on gas and now have the needed Diesel filter parts to see if she will go on Diesel. I was reading on the older MD's with a mag that when you switched to diesel it shut down the mag. Mine has a distributor and I just have mine hot wired at this point so need to know if the Distributor power would be removed when on Diesel and if so how this happens.

Thanks

Arnold Layne · Dec 13, 2012

I think it is, seems like my 450 had a switch in the front end of the intake manifold that went bad, I wired around it so the ignition switch controlled it all the time.

Hattrick · Dec 13, 2012

I have seen mutliple videos where they start an MD and cut it over to diesel but I do not recall any of them doing anything with the ignition switch but I might be wrong. It seems like there needs to be a switch off somehow.

n9lhm · Dec 13, 2012

The later battery ignition models had a two-terminal intake manifold that completed the ignition circuit when in gasoline mode. The older ones for use with the magneto just had one terminal and grounded it when in diesel mode. You need to get a later model intake manifold.

sflem849 · Dec 13, 2012

(quoted from post at 09:12:36 12/13/12) I have seen mutliple videos where they start an MD and cut it over to diesel but I do not recall any of them doing anything with the ignition switch but I might be wrong. It seems like there needs to be a switch off somehow.

You never did. It was part of the switchover linkage on the carb side. It did it all automatically.

The last guy to post was pretty much correct. Mag grounded out and coil broke circuit. I guess I said pretty much because he said you needed to get a new intake manifold...we don't know that for sure. You just said you avoided that area to make sure it wouldn't create a problem.

Hattrick · Dec 13, 2012

I will have to look at mine when I get home as it was the original with the tractor and mine is a 1953. The case/ih site shows a switch on the end of the intake like you say. I do not think I have one of those but I think there is a switch on the tube coming from the air intake canister that also has a tube type connection from the diesel side. With mine being a 1953 I would think that it would be the later one.

Dalrymple · Dec 13, 2012

n9lhm has it right. Here's a picture of a distributor equipped model with the switch bypassed (both wires connected to same post). Notice the post with no wire behind the post with two wires. Normally, the wire from the ignition switch would connect to one post and the wire to the coil connects to the other. When switching from gas to diesel, the mechanism inside the manifold breaks the circuit. Otherwise the plugs would continue to fire even when running on diesel.

As stated by someone else, models with a mag only have one post, which simply grounds out the ignition when on diesel.

Hattrick · Dec 14, 2012

So it looked like my intake manifold had a single lug coming from the switch. I took it apart and sure enough that is it. Maybe my tractor was at one time converted from a MAG to DIST. Can I use what I have and just ground out the distributor?

Dalrymple · Dec 14, 2012

No, you can't ground the wire from the ignition switch to the distributor on a battery ignition. It'll short out. You can install a simple toggle switch in that wire and turn it off after switching to diesel, back on before switching back to gas. That's the simple solution.

Or maybe someone has the parts you need to convert your manifold to the proper operation.

sflem849 · Dec 14, 2012

(quoted from post at 14:01:23 12/14/12) No, you can't ground the wire from the ignition switch to the distributor on a battery ignition. It'll short out. You can install a simple toggle switch in that wire and turn it off after switching to diesel, back on before switching back to gas. That's the simple solution.

Or maybe someone has the parts you need to convert your manifold to the proper operation.

Yeah, what he said.

I think I remember some talk about an ignition switch on this tractor. That would also be fine.

Dalrymple · Dec 15, 2012

(quoted from post at 19:20:04 12/14/12)
Yeah, what he said.

I think I remember some talk about an ignition switch on this tractor. That would also be fine.

The tractor already has an ignition switch, and you can simply turn that off after switching to diesel. I'm not sure what else is affected when you do that though. The amp gauge only? All battery charging? Lights?

If the generator continues to charge the battery with the switch turned off, there's maybe a very simple solution.

sflem849 · Dec 15, 2012

(quoted from post at 05:43:49 12/15/12)

(quoted from post at 19:20:04 12/14/12)
Yeah, what he said.

I think I remember some talk about an ignition switch on this tractor. That would also be fine.

Click to expand...

The tractor already has an ignition switch, and you can simply turn that off after switching to diesel. I'm not sure what else is affected when you do that though. The amp gauge only? All battery charging? Lights?

If the generator continues to charge the battery with the switch turned off, there's maybe a very simple solution.

Good call. I would take the multimeter out and that would answer the question in a hurry. I would guess it keeps charging etc.

Farmall MD ignition cut-out on Diesel

Hattrick

Member

Arnold Layne

Member

Hattrick

Member

n9lhm

Member

sflem849

Well-known Member

Hattrick

Member

Dalrymple

Member

Hattrick

Member

Dalrymple

Member

sflem849

Well-known Member

Dalrymple

Member

sflem849

Well-known Member

Similar threads