I have a chance to buy a D4 that is one of the first made in 1940, serial number 3J1939. It is in running condition and needs some TLC. The owner has a set of steering clutchs to go with it as well as a set of tracks. He tells me the mag isn't working at this time. He has been using it to clean up burnt brush piles. He is asking $4900.00 for it. I was wondering if this is a realistic price.

A 3J is not a D4 but is a D2 and a D4 would be a 7J in that era.

3J is a D2 40" gauge (center to center of the sprockets is 40") On a D2 the track frames pivot on a separate pivot shaft that runs across the tractor in front of the sprockets. A D4 will have the track frames pivoting on a "dead axle" that runs through the final drive bull gear and sprocket shaft.

So which is it? D2 or D4.

Probably the biggest thing on the value is what kind of shape the tracks are in. On the D2 tracks, height of the links of the track is 3.00" new, 100% worn is 2.75".

If the tracks are anywhere near the correct tension, look at the position of the front idler bearing on the track frame. If it's all the way out to the end, the pins and bushings are worn internally to 100%. It would be good to count links, since a link can have been removed to shorten a 100% worn track back to where it can be tensioned to keep it on the machine.

Also look at the bushings of the track links, they should be pretty round ,no pins showing through etc. They could already have been worn on one side and then turned and worn down on the other side as well.

Certainly should not see where the track rollers have been wearing into the sides of the track links and cutting into the bosses where the pins come through. This is a sign that both the tracks and track rollers are 100% worn.

Then look at the sprocket and idler. Teeth should not be pointed on the sprocket.

Can you tell that undercarriage is probably the most important thing determining the value of your prospective purchase?

Then on the steering clutches, if it won't steer properly, and cannot be adjusted to work, you would rather have a D4. The steering clutches can come out the top of the rear compartments of a D4 along with the bevel gear shaft instead of having to take off the track, track frame and final drive to change out each steering clutch on the D2.

Post some pictures of the tracks and measure them up and someone will have a better guestimate of condition for you.

On the engine, it's great it runs. Have you seen it run? Try to be there when it is first cranked on a cold morning. No fair restarting it while warm. This is probably the best quick evaluation of the condition of the main engine I know of. Also does it blow droplets of black "slobber" out the exhaust. That's pretty common, but it is a sign of a worn engine and one that needs to be worked hard and get hot.

Pony motor problems can get expensive if there are serious internal problems, but if it's just the mag, you can get that fixed or replace it. Usually once something isn't being used, it acquires other problems as well as the first one that stopped it, so I would also expect at least to clean the carburetor and fuel tank etc before getting it going properly. Then you may have problems with the pony pinion and clutch that engage the diesel flywheel just because they haven't been being used.

Other equipment adds to the value. Does it have a towing winch, nice dozer with tight joints, angle dozer or straight, hydraulic or cable operated? Brush cage and sweeps? Belly pan?

On the general appearance, how's the sheet metal, radiator fins, front grill engine side panels, seat and floor board pieces? Paint? Don't be swayed by a DUPONT overhaul!

good luck!, There's other tractors if that one doesnt' pan out!

Good luck.

Sorry folks it is a 7J. I haven't seen it yet just talked to the guy on the phone. I am aware of what to look for on the undercarriage as I used to work for a Cat dealer years ago. He says the tin is good, he is telling me there is 60% left in the rails but I would have to see it and as far as the rollers are concerned I am going to guess they are pretty much wore out, or maybe have a little left in them. He has purchased a D6C so want s to get rid of this one. He tells me he is willing to deal. I also would have to see it running.

A lower sale price doesn't always make the deal much better either. The price tag to look at is what you will have in it when it is in servicable condition. If the undercarriage is still worn out after all of your other work is done, you still won't have very much of a value. A crawler bult before 1960 with a like new under carriage is rare. I bought my D4 7U for $1,500 at a farm auction. It had a good under carriage but the steering clutches were stuck, upholstery was gone and many more things needed attention. I did most of my own work and now I have $7,000 into it. I would have been better off spending about $10,000 for a ready to use Cat in the first place. I could have got to use it a lot sooner too. The positive things in this whole story are, "Look at all of the wrench experience that I gained." and I met a lot of nice Caterpillar people too.