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I have the opportunity to pick up a 70 diesel, I have a 70 gas currently that I'm thinking of selling. The diesel has been sitting for eight years but was moved about two years ago. The current owner knows nothing about it, it came with the property he bought. He said the guy who moved it thought it was in great mechanical condition. It seems to be complete, with power steering and three point. I assume I will need to drain the diesel and gas tanks and possibly clean the pony motor carb in order to try and start this thing. He said the guy that moved it bump started it, which I'm assuming he couldn't get the pony motor going or didn't try. Is there anything else I should do or look for to try and get the motor started? Also, is the diesel just more complicated and harder to work on then the gas model? Any input would be greatly appreciated.
 

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Keep the gas and buy the diesel. Then you’ll have two. :)

Diesels are different to work on. Injector pumps instead of carbs. Two engines with the starting one.

Would be a neat project though.


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I have the opportunity to pick up a 70 diesel, I have a 70 gas currently that I'm thinking of selling. The diesel has been sitting for eight years but was moved about two years ago. The current owner knows nothing about it, it came with the property he bought. He said the guy who moved it thought it was in great mechanical condition. It seems to be complete, with power steering and three point. I assume I will need to drain the diesel and gas tanks and possibly clean the pony motor carb in order to try and start this thing. He said the guy that moved it bump started it, which I'm assuming he couldn't get the pony motor going or didn't try. Is there anything else I should do or look for to try and get the motor started? Also, is the diesel just more complicated and harder to work on then the gas model? Any input would be greatly appreciated.
Here's the starting routine for your JD 70 Diesel:

 

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The 70D is a bit more complicated, but it is also a legendary and powerful two cylinder machine. I'd own one in a heartbeat, especially if I had room or need for one. :good2:

The pony motors can be a PIA. Parts are difficult to find and expensive. Many 70D's were converted to electric start for this very reason. If the pony is in decent shape, keep it. The tractor is considerably more valuable with it and the cool factor goes through the roof.

Get the 70D and don't look back! We'll need lots of pics and videos! :thumbup1gif:
 

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Discussion Starter #6
Thanks for the info. I've been researching the diesel and other than the more complex starting procedure, its pretty much the same as the gas as far as power and weight, but way more fuel efficient. The main reason I'm considering the diesel is for the power steering (as well as the cool factor). I have a Duall Loader on the current 70 and its a total beast to steer. It pretty much takes 3 feet and 4 hands to operate the loader and the tractor. I think I'll make an offer on it, but try and get it fired before I do.
Also, my tractor is 12v negative ground. Would the diesel be the same? I looked at the Tractor Data website and it says all 70's were 6v positive ground - is that correct?
 

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You almost can't go by what is said on the internet these days concerning the electrical systems on the old 2 cylinders. So many were converted. So many were changed, it's hard to be accurate on what yours should have.
 

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OEM was 6V positive ground for starting the pony. Pony is far more reliable starting in cold weather than electric start.


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Here's the starting routine for your JD 70 Diesel:
Not all of the 70's used the same system to start the pony motor, the one I had used the lever forward to start the pony, then all the way back, then forward to engage.

And, yes, 6V positive ground!

I much preferred the electric start 720's we had! GARDEN TRACTORS 043.jpg
 

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I much preferred the electric start 720's we had!
I came close to buying a 720 once. Passed and let a friend buy it. Got to work on it anyway..........:laugh:
 

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I came close to buying a 720 once. Passed and let a friend buy it. Got to work on it anyway..........:laugh:
I grew up on the one in the picture, Dad bought it new (as a leftover) in 1959!
 

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the pony is something all unto itself...they are 4 cylinder, dual coils. ahead of it time in that aspect, but the first time you forget to shut the ignition off after the diesel is running you will learn that you burn up coils quick, and at 70 some bucks, it hurts forgetting. You can put in a pressure relay cut off which saves your coils, the relay makes once you have oil pressure, drops out when you shut it off. One of the things i do with mine are to drive the tractor around using just the pony. The biggest problems on the ponys were they would get started, run wide open for 10-15 seconds, then get shut off, never really get warmed up or to a normal running temperature.

With respect to your statement of trying to get it running before making an offer, if i was the owner i would tell you not a chance, cause if you screw something up who is on the hook for it? a full rebuild on a pony isnt cheap. Usually what happens is a motor isnt stuck, someone goes and starts moving the flywheel then it sits again and gets stuck within a week. All that oil has drained down years ago, so you have dry rings and walls, better off leaving it alone till you KNOW you are going to get it running or at least turn it over enough to make sure things got oiled good again.

If its been sitting a few years there are a few things that will likely need replaced like the water pump, the fuel transfer seal, stuff like that, but if there is no fuel in the oil and the big motor isnt stuck, tin is in nice shape, rubber is good, then make a fair offer, cause these tractors show up a lot more than you think. Does it have live power?

I have a 70 diesel standard that has hydraulics, 3pt, ps, a r/c, an 80, 720 diesel r/c, and an 830, these big diesels are brutal, but not forgivin on the pocketbook.

They are 6v pos grn, but a big truck starter will work, cant remember which one. but i think its only a 10, 11 tooth.

Good luck.
 

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Discussion Starter #13
This particular one has a push button start for the pony. I couldn't try it because the battery was missing and he didn't have a 6v.

The owner told me to feel free to bring a battery, some diesel and gas to see if it starts. He also said I could bump start it if I wanted. Like I said before, he knows nothing about the tractor, just want's it to go to someone who will use it.

I believe it has live power, it's got the same controls as mine (engine driven pto with an engage/disengage lever, and clutch lever).
 

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all the ponies had a push button starter. the rest are mechanical linkages to engage the pony clutch to the big motor flywheel. you can replace the pony with a 12v big truck starter. none the less, if you try and pull start it make DANG sure that the fuel cut off pull cable works or you can get to it to shut it off, other wise you are gonna have to kill air or fuel to it and neither are a lot of fun on the fly hahah
 
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