Header image

New to me 1936 Caterpillar RD4, get it running project

m1west

Well-known member
GOLD Site Supporter
Well, I'm done licking my COVID wounds and worked on the old cat some today, I drained the molasses and water mix from the pony gas tank. It got some extra time to work when I was down. First cleaned it thoroughly with water then acetone to get the last bit of water out. Also cleaned the fuel shut off and sediment bowl with acetone to cut some white pasty residue in it likely caused by ethanol fuel that dried. Next go I will check the tank for leaks one more time then paint it, then put the carburetor and magneto back on and the pony is ready to run again. I still have to remove the inspection cover on the main and check things out, clean the oil pickup if necessary then re fill with oil. I have to put about 5 gallons of gear oil in the main gear box add some water to the radiator and it will be ready for a go also. I have some other distractions going on right now like real work and I am also finishing up some work I am doing on my boat. I lost a month with COVID, but at least its not too hot anymore.
 

m1west

Well-known member
GOLD Site Supporter
Today, I put the magneto, carburetor and the linkages on the Pony. Next to check the gas tank for leaks agin then paint it, put the gas tank back on with fuel line, after that it will be time to pull the rope.
 

300 H and H

Bronze Member
GOLD Site Supporter
Interesting..

I was looking for your pony motor exhaust to run through the intake manifold for pre heating the main engine.
My D4400 Gen set has such a set up. I have been told no matter how cold, it the pony lights up, you will get the 4400 running.
Hope the pony fires right up for you! :thumbup:
 

m1west

Well-known member
GOLD Site Supporter
Interesting..

I was looking for your pony motor exhaust to run through the intake manifold for pre heating the main engine.
My D4400 Gen set has such a set up. I have been told no matter how cold, it the pony lights up, you will get the 4400 running.
Hope the pony fires right up for you! :thumbup:
Yes I have not experienced it, but reading says that turning the main under full compression with the water from the pony helping heat things up in moderate temps. I should have to crank it 3-5 minutes do get enough heat for the main to fire when given fuel. That said, when I pull the oil pan inspection cover, I plan to spray some oil on the cylinder walls and pour some down the push rod holes to get some on the cam lobes before trying to fire the main. My machine is an early one, the pony exhaust is not routed through the intake of the main.
 

m1west

Well-known member
GOLD Site Supporter
Today I was going to clean up and paint the pony gas tank. When all cleaned up the bottom was full of pin holes. So I had some 16 ga. stainless drop and started making a new gas tank.
I will have to pick up a 1/4" weld in female for the sediment bulb to screw into and a 1" half coupling for the cap to screw on to and a couple of blind nuts for the mount. The good news is, when someone unearths it 1000 years from now they can identify it by the pony gas tank that will still look new.
 

mla2ofus

Well-known member
GOLD Site Supporter
If you can't find the 1/4" weld in just cut a black coupler in half. Boy, this has turned into a labor of love for you!!
 

m1west

Well-known member
GOLD Site Supporter
Today while was working on the new gas tank, decided to put a little gas down the carburetor on the pony to see if could get it to start. I can see I am going to have to rig up a motor to start the pony until I start the main. The pinion is engaged and there is no way to disengage it until the main fires and the dogs kick it out. Even with the clutch disengaged there is too much drag to start it with a rope. I watched a couple videos where a electric motor was rigged up temporarily to do the trick. I plan to rob the motor from table saw, as it has a very small pulley on it for torque, bolt it to a plate clamped to the fender and let it rip. I got it to make one pop while trying to pull start it for 15 minutes before gave up.
 

mla2ofus

Well-known member
GOLD Site Supporter
You could probably crank it with a 1/2" drill, Just be sure to take the left hand screw out of the chuck so when it starts it'll just spin the chuck off the drill else you'll be lookin' for a new screw and figuring out how to get the broken one out. Ask me how I know this, LOL!! I use this method on small engines so learned this lesson long ago.
 
Top