Will 720D pony starter fit 70D?

DrCharles · Oct 16, 2017

My 70 Diesel starting controls have been modified by previous owners. It now has the two-lever system from a 720D and the stubby starter pedal from a late 70D to mechanically engage the pony starter motor. (The parts catalog shows it was originally supposed to have had the single-lever system and no pedal, since my S/N is in the low 20,000 range and the pedal wasn't used until #26,870).

I like the two-lever system, but the pedal is difficult to engage because it's in an awkward location and requires a good push to physically engage the starter pinion with the pony flywheel. The 720D used a starter with a Bendix drive, so no separate engagement lever is needed, just a push button on the panel to power the starter solenoid.

If I find a 720D pony starter, will it mechanically bolt up? The button wiring is trivial.

thanks
Charles

johndeeregreg · Oct 16, 2017

i have no experience with the 70 diesel but i would think you can make that swap. some one that knows for sure should come along

Blksmok · Oct 17, 2017

Depending on the s/n of your 70D you may have clearance problems between the starter mounted solenoid and the back of the dash/shift box console. I've relocated the solenoid to the inside of the battery box to solve this problem of some of my 70D's. You can use the cigarette lighter hole in the dash panel for mounting the momentary push button.

DrCharles · Oct 17, 2017

Relocating the solenoid is no problem... thanks for the tip. What is the interference on the early 70D - the starter linkage, or something else? I have now bought a good used 720D starter (1107155), so I guess I will find out eventually

Of all the "features" of my 70D, I think that starter pedal is the worst!

Meanwhile, at least on my tractor, the red indicator lamp is connected directly to the IGN position on the switch, so whenever the pony ignition is live, the red light is on. The later model diesels seem to have an oil pressure switch in series with the light - is that switch plumbed to the pony oil pressure or to the main engine? I assume that the red light is supposed to come on to remind you to shut off the pony after the main engine starts, so that would imply it's fed from the diesel? Or is it intended as a warning that the oil pressure is low... again, which engine?
Thanks.

Dan in Ohio · Oct 18, 2017

Charles,
On the 720D that light is tied to a simple (inexpensive) pressure switch that is plumbed into the side of the pony block. That plug is very hard to reach while the pony (cranking engine) is in place and there is no guarantee it will come out easily with the engine removed. A few of my tractors have the automatic fuel shut off plumbed into that pressure switch as well. FIT was the one who installed the pressure switch as a means to "Save them Pony Coils". This is a value added option for those of us that have ever left the ignition turned on inadvertently. There has been discussion here and in print on this topic, some on here has been removed.

Blksmok · Oct 18, 2017

Check Ebay...I have a listing on there for all the parts you need to put the "oil pressure switch" system on a 70D. The parts came from a 730D pony engine.

DrCharles · Oct 18, 2017

Thanks... I actually have the auto shutoff and pressure switch. They came with my tractor (the pony was put back together and on the tractor with only one piston and rod inside to make it look complete for auction! I bought the tractor from the guy who'd been "taken"). Since I always remember to shut the pony fuel off, it's just one more thing to break down. Also a potential path through a leaky diaphragm to put gas in the oil). So I'm still waffling about whether to install it. Not concerned with originality

DrCharles · Oct 18, 2017

Thanks Dan. I was playing "what was I thinking" with long-gone Deere engineers from the 50's

Like I said, mine is hooked up without the pressure switch so the light is on any time the ignition is on. A few minutes more wear on the bulb filament but then it's a constant reminder...

I am planning to take the hood off soon anyway (the carb, fuel valve and air cleaner all need attention). Is it still hard to reach the plug with the hood removed?

Dan in Ohio · Oct 18, 2017

It will certainly be easier with the hood removed although my last attempt at removing that little plug was unsuccessful even after loosening the pony and lifting it up to do some trans/clutch work. Did not spend too much time on it, just thought while I was there I would fix that, just could not get the right tool on it or was short on patience that day.

Will 720D pony starter fit 70D?

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