1940 D6 advice

 [attachment=76278]IMG_0998.png[/attachment] [attachment=76278]IMG_0998.png[/attachment]

Congratulations on saving a bit of your history Brant. For your questions:
Pony Motor: Carb getting rebuilt and new spark plugs purchased
What gap should the spark plugs be? - I don't know, someone will, but starting at 025 is probably a good starting point.
Grease gun 50303: Where can I purchase one? Someone may have one to sell used - try posting a Want ad in the For Sale section of this forum. You can also buy an adaptor for your normal grease gun to enable connection to the larger fittings some of these tractors have. You just need to not apply any pressure as the old greasers applied very little pressure as the seal design meant they could be damaged with higher pressures
Engine Oil: Still shows full and good color. Do I need to drain and refill? You should at least take a sample from the drain plug to check for water and other contaminants that may have settled. Drop 8oz out to be confident. Weight and quantity? The original service guide probably recommended 30 weight and if you want to, you can look for non-detergent 30, but you can also use "regular" modern diesel engine oil I think (someone will know if any of the modern additives are harmful to engine components, usually bushings and bearings) - just be prepared to change the oil filters early in case the oil's detergents dislodge accumulated crud in the engine
Engine Oil Filter: I believe its 2A2473, any good places to purchase these? Try your Cat dealer - he may have superseded this part number. Also search this site for aftermarket alternatives
Fuel Filter: I'm not seeing a filter anywhere in the parts book, just the "element" assembly 6B3447, should this be replaced before starting? The element is the filter - it's basically the filtering element that would be inside a modern disposable filter. By all means replace it before starting if you want, but I'd almost be inclined to leave it in to catch the crud that has inevitably settled on the bottom of the tank, and then replace it after catching all that crud. If you can't get fuel pressure, then you probably should change it
Am I missing anything else? All help and advice is much appreciated!

Welcome Brant, just have a quick look inside the fuel and oil filter housings, you may find that the original brass re-usable filters are in there, they were designed to be washed and re-used, if you find more modern disposable filters in there, get the part numbers and go buy some.

Look on Fleabay for a copy of the Operators booklet on the RD6 tractor, and buy it, you should be able to get one cheap, that will have all the good info you need for proper servicing and adjustment of that tractor, like the filters, and carb, magneto, clutches, brakes, etc. I have one running RD6, and a couple of project tractors, and really enjoy driving mine.

Oil pressure is critical before actually letting the engine start, if you have doubts about how good the oil gauge is, get a known working gauge, and plumb it into your oil system.

The later built RD6 were called a D6 by Cat, but when you buy the operators book make sure you get the one for the 3 cylinder diesel RD6/D6, engine and frame serial numbers start with 2H, and not the later 6 cylinder D6 models, starting with 4R/5R or 8U/9U.

I use either straight 30W or 40W engine oil in mine, what ever I have on hand, as others has suggested, check all oil compartments for condensation before starting the tractor and moving it, I like to have a suitable piece of wood to put over the air intake, like a piece of plywood, after removing the mushroom shaped cover first, if the engine runs away you need to move fast, with the minimum chance of screwing up.
Good luck, enjoy the journey
Mike

You want to use a detergent oil, but anything labeled as diesel engine oil will be detergent. My grandfather had one of the first Diesel Cat 35's in 1934. It got worked on by Cat a number of times as it burned oil and the Cat dealer got to use it as a demonstrator it to prospective buyers It was only with a breaking period of varying load at varying RPM, AND THE BRAND NEW DETERGENT OIL that Cat help develop did it stop burning oil.

As I understand it the Cat dealer drove it off the flat car and put coil tine chisel plow or disc plow behind it to show all that would come see it just how much it could pull. Most of the old Cat engines will tend to slobber carbon and oil when left to loaf along with very lite load like parades or just idling in general. So don't encourage this by using a non-detergent oil as well.

As Mike stated no oil filter in the beginning, but they made a kit to update to filters which I believe are still a bypass element rather than full flow. But again guessing they have had another update to turn them into full flow systems. So if the cap to the filter assemble has T handle to unscrew it from the bottom a by pass filter. If it is a hex nut it would be full flow system. Start with 5 gallons of oil for the diesel engine.The picture on the spec sheet shows the oil filter and it has the T handle inducating it is a by pass system on that unit.

the grease fittings are cheapest from your local cat dealer if you have to replace any. alemite and mcnuaght both have adapters for the 7/8 giant button couplers that have a standard zerk fitting on them about 40 buck when i last priced one.

dont forget to cover the exhuasts to keep water and crap out a old spin on oil filter casing works well as the end is domed it sheds water. as the pony exhuasts through the main intake and this can easily rust out and dust your main engine.

neil is correct the plug gap should be 25 thou if the plug leads are sad you need proper copper wire leads with metal ends, not silicone suppression as only copper will work(learnt the hardway. got nice new NGK brand insulated ends from the local motorbike shop and they wouldnt work.)

as for oil get a recomendation from your chosen oil company and run that. we use delo gold 15w40 in our old girl. the final drives use torqueforce 30? it used to be called torque fluid 454 but they changed the name and i cant remember what it was changed to, and havent bought any for a couple yrs as we bought a couple of drums last time as it was on special.

Yes forgot to talk about the grease. I am guessing to late to look around for grandpa's bucket grease gun. Because he sure had one if he really used old Cat's. Just look up Alimite grease fitting and figure out what size is on your tractor. Then use a regular grease gun and buy "corn head grease" in the tubes. The seals on the roller will blow out at a very low pressure so don't use a battery powered grease gun. Just pump carefully and at the least amount of resistance STOP.

It seems your dad and grandpa would of had it greased before storage so maybe just a few pumps so you know there some in the roller would be good for several hours of putting around.

Gearbox and final drives use a heavy grade gear oil, I use 85/140W in all my old Cats, they do not run light weight oils in those compartments.