420 egine reassembly

[millertym2]

I looked at a 420 that has been sittin for a few years.The guy has the piston rods and crank shaft out of it.He said he had oil pressure problems. I am trying to get it from him-but I am wondering how much of a pain the engines can be---especially when the bottom has been sitting open 6 inches off the ground for so long. I have delt with the track and steering part of them but never the engine. Any advise would help.

Thanks,carl.

[Lavoy]

Engine parts are quite plentiful, I guess I would not really worry about it. As long as you are going to do it, do it right and do a complete rebuild, then you will not have to worry.
Lavoy

[millertym2]

Thanks Lavoy, That helps.I wasnt sure if it would be worth it if the engine was junk. Now I just have to work on the old guy to get the 420 from him.

Thanks again!---carl.

[Stan Disbrow]

Hi,

Not to worry. They can come back from being *way* dead with greater ease than sitting and watching TV.

Well, maybe not quite that easy, but pretty darned easy.

Story Time:

This is about a poor, old JD 'M' wheel tractor. Sorry about that (in a crawler forum). :p

A bit of history. My uncle came back from WWII and opened a JD dealership. He had been a milk tester for the county, so he knew all the farmers around. My dad was a machinist, with his own shop, but did a lot of work for his brother, of course. I spent a lot of time in both places as a kid.

Anyway, uncle sells this M to a dairy farmer in 1950. He uses it with a dozer blade to scrape the barn for decades. In 1978, the farmer passes on, and the M is sold - to dummies. They want to use it for snow plowing (oh, we were in upstate NY in those days, which I suppose I ought to mention since my location says NC).

Unfortunately, they, unlike the farmer, leave it outside all the time. Uncovered. With no cover on the stack. You know where this is going......

Yep. Water in #1. Freezes to boot. Won't start. 'How odd, let's jump it with 12 volts'. Nope won't budge.....

Now, you'd think that a light bulb would pop on at this point. But, no. One has to *have* a light bulb to turn on, and these guys were a few filaments short of that. BTW, the guys in question were school mates of mine, so I know *exactly* how dumb they really are. If only they went to get their dad at this point, but they didn't......

So, what now? Yup! Pull start it! With a 4x4 truck. At 30 MPH on the town road. With the tractor in 1st gear. You know, the engine will spin faster in 1st, right?

As I said, a few filaments short of a bulb here. Might be missing the glass envelope as well, now that I think of it. :p

Well, it musta taken a few tries locked up to kill the M. I still have the original rear tires, and there's lots of small chunks missing from the lugs.

So, anyway, the front end casting eventually parts company with itself. Oops. No more front-end. Whang! Onto the oil pan it drops. I won't say what happened to the radiator, only that I'm *really* good with sheet copper, solder and a torch. I wasn't when I started, but I am now. It lives still.

Now, they dragged the thing back, on it's pan, and dumped it behind a shed. For 10 years. Eventually my dad talks their dad out of it. Good thing we had a rollback *and* a pickup truck to haul the bits home.

First thing we did was weld the front casting, then cut some 'jigsaw piece' plates to sandwich the pieces so the weld won't get stressed. Oh, and replace the axle pin with a bolt for a little extra support. That gets the machine up where we can work on it easier.

Other problems? Well, an oil pan full of water. The dipstick is eaten away to the top of the 'add' line. Two frozen-in pistons. Number one is caved in on top. Two bent valve stems. Two bent pushrods. One bent rocker arm shaft. Crank and rods are OK, as the water didn't quite get up that far.

We had to yank both pistons up through the top with a puller. To do that, we had to remove about half of the top of each. They were stuck with rusted oil rings. Fortunately the remains of the rings cleaned up easily, without resorting to the boring bar.

Dad decided that the machine had to run with the parts we had. He wouldn't spend the money until we could run it to see what might be wrong in the transmission, differential and final drives. So he fixed everything. All we put in new were rings.

Yes, that means he fixed the pistons, too. That's not too hard with cast iron as it turns out, if you're a good machinist, as he was. It was meant to be temporary, but we did all this back in 1988, and the poor old thing is *still* like that. Me? I figure, if it ain't broke, I'm not going to fix it. Besides, I get the biggest grin on my face every time it fires up.....

Also as it turns out, the only other fault was a chipped tooth on the right side bull gear in the final drive. I fixed that with some stainless steel weld and a few files to recut the tooth.

Oh, and the hydraulic system had become contaminated when the machine split apart. It took several disassembly, clean, reassembly steps to put that right, but eventually it was made to work right again.

I still use the 'Poor Little M' for light work. I wound up painting it with the new JD green and added the incorrect yellow stripe (make it look like a 420), but what the hell? With those flat-top pistons in there, it has more compression than a 420 anyway, so it deserves the 'go faster stripes'.

Those pistons make the thing pop with a sound unlike any other JD I've ever heard. It's more of a 'crack' than a 'pop. I suppose that's why dad left them in there. He always had a grin when he heard it start up, too.

So, don't be too worried about how far one of these old things can come back. The answer is 'pretty danged far'!

Stan

[millertym2]

Hi stan,
Great story! Its amazing how far we will go to save the unsaveable.
Here's my story.

Growing up my father had a bunch of cool toys for me to play with as soon as I was able reach the pedals.
He had 2 JD b's(1 for parts and the other to skid logs for fire wood)

Two "doodle bugs"For those whom never heard of doodle bugs,they are old trucks made into logging trucks.Maybe its just one of our NY back woods terms. He also had a real tow truck from when ran his own shop.

But my personal favorite is the JD mc with a blade. Just to tear things up.

Well after my father and mother divorced ,It took the wind from his sails I guess you could say. And he let all the equipment go and slowly they all ended up just sitting outside. The only thing that he kept going was the towtruck.

After he passed away in 99,my sisters and I split everything up.One sister just wanted some land.The other sister and bother inlaw wanted the B's And I got to keep the rest. I am saving land for my younger sister till she is ready for it.

I was too busy working and getting my life in order to start fixing things.But my bro-inlaw is a mechanical genious and loves to tinker. He freed up the B that was in better shape than the other.The block was cracked form water sitting in the belly pan and freezing. And naturally the cylinders filled with water and solid rust.He removed the head and used a port-a-power to move the pistons back and forth. But now she's in mint condition.

Here's the crawler part.Two years ago I got my but in gear and started in on the mc. It would'nt steer and the track would roll off very easily.The engine is the only thing that didnt need work. I have rebuilt the steering clutch's on one side(thanks to Lavoy's parts). So now I can limp the old girl around. I have taken pics. Of my project step by step.
But I still have to pin and bush. the tracks,Rebuild the other steering clutch's,fix up the blade arms and get her all dolled up.

Now the 420c with the engine all apart ,is (hopefully) my next project. So now I have a pretty good idea the engines arent that bad to fix.Thanks for the info. I will get my progress on here soon.With christmas coming I keep hinting the 420 would be a GREAT present!!

Thanks again,
Carl.