Howdy Folks 
Just bought my first Caterpillar, D2 5U1731.  “Ran when parked”.  First task will be to try and get it running, so I can load it on a trailer.  I’ve been watching the D2 startup you tube I stumbled across in the forum.  Great video that sets me up for success!  I’ll take any advice I can get too!  Hopefully it’s in as good of shape as I’ve convinced myself.

Looks like a pretty solid tractor. If both motors are free and turn cleaning the starting motor carburetor and magneto would be a good place to start

  Howdy again,
I got into my first in-depth look at the D2 today. Wife came along and helped me out, and she seems to approve of it which is always good! Fortunately we brought the EZ-up, forecast was for rain and it came true.
Couple things concern me: Gear shifter is froze up. In neutral, but not budging any direction. I gave it a few real light taps,, but didn’t want to get too rough with it. Oil on tranny dipstick looked good, but there was some rust on the dipstick. I didn’t have a socket to open the drainplug, so will need to find a massive hex tor those. Recommendations? Should I soak the shifter and try to pull it off?
Also, engines are both free, but the main engine would turn when I pulled the pony motor over. I could hold the main engine with a 2x4 in the fan & belt, and the pony would still turn over fine, but otherwise the main would turn too. Is this just friction at the starter clutch, or is something wrong?

The gas tank was a mess, so I brought it home and have already started cleaning it up. The gas fuel lines were a hack job with rubber hose, bypassing the original second shutoff valve. I brought the valve home too, and have discovered the filter in there too.

Good news: I pulled the top off the carburetor, and the float bowl looked great. Also it has good spark, so I’m going with that for now.

Main engine looks good, glad she turns over. Water pump seemed to weep a little after I turned her over a few times, but antifreeze is visible in the radiator. I need to check for water in the crankcase and tranny, so need to get those plugs loose. Good oil level in the injector pump, and oil looked normal but dirty.

I’ll take any advice I can get. I’m a mechanical type guy, but this is my first CAT. And I’ve gotta tell ya I’m really excited about it! Can’t wait to get her running and bring her home!

Hey Potato looks like a pretty sound machine to begin with.
Any idea how long it has been since it last ran?
The shifter problem may be simple or complicated. Is the rubber boot over the shifter intact or split and leaking water. If so try some penetrating oil in the boot and let it soak for a few days. Problem may be here or could be internal.
Main and pony engaged means the pony and starter pinion and clutch are engaged. Not sure on the D2 if there is a small hole to see the pinion and the release. May need to remove the pony to get the pinion out to work on it.
Look for a set of manuals for the machine. They are most helpful for repairs and identifying parts. Some other will chime in here.
Several videos on YouTube by squatch253 many on the Cat D2

Good luck!

Welcome aboard! Sounds like things may hopefully be fixable enough to get it running and onto a trailer. If not... at least it's stuck in neutral and not in gear!

Good morning and Thanks Gang!
It's been sitting for "5-6 years". Which of course could mean more. And it's rained like crazy the past couple winters. The rubber boot is at least there on the shifter. But chances are it's cracked. I'll get some Kroil in there to soak. And I'll double check, but I'm pretty sure I tried the shifter with the clutch lever all the way forward. I'll pull the cover and check the operation. Sure appreciate the advice.
Also I found the posts on making a drain plug socket from a bolt. Excellent.
One of the things I've read about is excessive end-play on the pony motor. This one has a little bit, not as bad as some of the video's I've seen but beyond spec I'm pretty sure. What is the risk running the motor like this?
Circling back to the starter pinion... is there a way to release that while the machine is at rest. If I remember correctly it automatically releases when the diesel engine fires up, and then has to be re-engaged at the next start up. Do you engage it before starting the pony motor, or after the pony is running?

Thanks again everybody.

Hello new guy, I think the D2 looks good. I know the drain plug wrench is easy & cheap to make as previously mentioned. The Caterpillar inverted hex plugs have a tapered hex and a shop-built wrench only contacts only a fraction of the inverted hex. That still works but the proper wrench is still available from Caterpillar P/N is 212-8146. 
It's nice to have just for the bragging rights! lol
Craig

 

Welcome, "Potato"! Looks like fun D2 time. I think I see a U series with a toolbar dozer, very similar to one that I had rescued a few years ago. Any knowledge of why the machine has been parked so many years? Do you have a way/place to work on it out of the open? Does your clutch lever move freely? I have come across some that have the pivot shaft rusted and froze tight, etc.
You will get many hours of enjoyment fiddling with your new catch, as well as play time on the seat. Enjoy and keep us posted please. JM