Pony Motot Rebuild

Since that pipe seems to be stuck in the pony, I am going to attempt engine removal with the pipe intact. Maybe after the whole mess is sitting on the floor I can use the heat & penetrating fluid method mixed with a lot of patience.

I know that you must have dealt with this, Frank. As always, any input from the millions and millions of steadfast Deere fans on this board would be greatly appreciated!!

Luckily my water pipes came right out, just by twisting!

Brandon
My Industrial John Deere website
John Deere Diesels
The LaGrange Engine Club

Give me a shout when you go into the pony transmission. I went through the one on the '70', and while yours is somewhat different in design, I can tell you some reasons for the symptoms you describe.

Frank

It really takes some time with the parts books to determine what is truly common and what is not. But we can get close for conversation purposes only.

The 70-720-730-80-820-830-840 used the same V-4 engine, though there were some internal improvements along the way. That said, you could interchange them and only offend the correct police.

The 70-720-720 used a different pony transmission than that used on the 80-820-830-840, so if you have one to swap with the other, you'd have to swap transmissions as well.

Later ponies had a thermostat in the cooling system, along with a recirculating by-pass tube. That means the manifold and water pump outer housings are a bit different.

Later ponies also received serial numbers.

HTH

Frank-in-Tallahassee
70D // 855 // VAC
[email protected]

• F-I-T's webpage.....ALWAYS under construction....

Also, somebody in Wisconsin(that's where this came from 2 years ago) must have thought of the pony protection ciruit eons ago. This thing has an oil pressure activated switch wired in. I will have to check the wiring to see if it is actually the F-I-T endorsed setup.

I think all the 720's and beyond had thermostats, but they began assigning serial numbers maybe at the black dash changeover.

Your 720 has an oil pressure switch but I believe it's for the lamp, not the coils. It possibly could be used for that, though.

But I think the F-I-T/Clooney circuit is still unique!

Frank

The ends of the water pipes, upper and lower, are just resting in small o-rings. I wouldn't be afraid to apply some judicious heat to the end area. It will probably loosen up with even a bit of propane torch. You're going to replace all that stuff anyway. But you're right in that the pipes are nla, so you wan to be real careful with them.

Frank

I already do love the little fellow or else I wouldn't be dumping money into him! It ran very well with the exception of the blue smoke screen and the water pump seal that just went out and don't forget the plugs fouling on the front head.

Well the little guy is sitting on the garage floor and after at least an hour of scraping "goo" off of him I'm ready for disassembly. Need to study the service manual for a while to make sure that I do everything right. This is my first attempt at a pony and I wouldn't want to ruin any of those tiny parts that are made of unatanium!

I will keep everybody posted on the progress of the "labor of love".

P.S. That darn water pipe still won't budge. Patience, patience, patience!!

Are talking the pipe in the water pump, or into the manifold? Either way, cooking the two pieces together in an electrolysis bath (hook them together with a jumper clip) and in a day or two, they'll wiggle right apart.

Frank

It is the large pipe in the manifold. That sucker seems to be rusted together. I was able to "wiggle" the small one out, but the big one is bad news. The pipe seems pretty solid, so maybe I will venture into the "dark side" of electrolysis. That manifold sure looks like it could use a good rust bath.

The good news is that the heads are off and the bores look very clean. Not even a noticable ridge. One valve looks to not be seating well, but the others look pretty good. I will check everything out and possible go with new valves and especially guides.

By the way, I noticed that the rocker arm pivot rods seem to wear on the underside but nothing on the topside. I think it might be prudent to flip them over when they get reinstalled. Any thoughts would be appreciated.

You know, you might just want to get it pretty warm now that you have it off. I bet it will soften and come on out. Who knows, someone could have used some JB Weld in there, which means it will take heat to soften it anyway. If you find rust and flakes inside the engine block after you remove the sleeves, you might want to try electrolysis on that. On mine, it was absolutely packed in there with rust. I know it cools better now!

Frank