I have an early mid-Seventies CAT D3-79U (Japanese build) that is missing the steering brake/clutch compartment drain plugs.  This is a dry clutch arrangement.  I have the manuals but have not been able to locate the part number for these two plugs that are at the bottom of the beast.  Anyone out there who might be able to help?  Many thanks,  -Tom

We've had this discussion before and the conclusion was: The magnetic drain plugs are part # 8M3837 and the non magnetic are #6B5262.
Both are 1-1/8 x 12tpi and use the same 6K5551 gasket.

Many thanks. As a new member I haven't learned the protocol of the site but will try as time goes on.

The 8M3837 magnetic plug is the correct plug for your machine according to SIS. Apparently there are 5 on the steering clutch case.

Also keep in mind these plugs are sometimes removed to hide a leaking seal issue.

The plugs were some of the missing items when I got the machine. I just replaced all of the recoil group on the left side, and replaced steering clutch group on same. Still haven't found the location of the plug in my parts book (from Jen-Sales). I'm just setting up to do pressure readings for the clutch servos as soon as the adapters arrive. This machine had the bejusus beat out of it with little or no maintenance. Just resealed the 6-way blade cylinders and working on the blade ball mount assembly which was missing the trunnion cap, broken and welded mounting bolts and all. Hoping to find replacement sheet metal covers for the left side which are also missing. Little by little it's coming back to life! Thanks, -Tom

iowahill what is the liquid in the pot to boil the rust off? I have never seen that before, looks like plenty of items to keep you busy on the list of to do.

Shown as item 13 in phantom view in the parts book

That pot of liquid is an electrolysis setup consisting of water, some washing soda and an old school (non electronic) battery charger. There are other methods and videos on YouTube.
 I have used electrolysis with impressive results on many things. I managed to resurrect a D4 2T in the pictures below. All new liners a few rings to replace the broken ones and a valve job on the head, that's it and now she's a runner.

CrawlerAddict 
                   

Certainly makes impressive results and I imagine a lot less time attacking the rust and scale by hand, nice work

It's a solution of washing soda/calcium carbonate or baking soda (Arm & Hammer brand in the detergent aisle of your market) and water.  12-volt battery or charger with negative lead connected to the work, and sacraficial scrap steel or iron somewhere else but not touching the work.  Google "electrolytic rust removal" and there are plenty of links for setup and process.  Here's an excerpt that pretty well sums it up:Electrolysis MaterialsPerform electrolysis in an area with plenty of ventilation since it releases small amounts of hydrogen and oxygen gasses, which could be flammable if they build up.To remove rust using electrolysis, you’ll need:

• Battery Charger: A basic 12-volt car battery charger will do the job.
• Electrolyte: Washing soda (sodium carbonate), such as  Arm & Hammer Washing Soda , is the best electrolyte to add to water to remove rust. It’s sold as a laundry booster, and can be found near laundry detergents in stores — don’t confuse with baking soda (sodium bicarbonate).
• Water: Warm water will dissolve the electrolyte faster, but tap water is fine.
• Cathode Metal: The tool or other metal item you’d like to clean.
• Anode Metal: A scrap piece of iron or steel (not stainless steel). The anode is reusable, but it will be gradually eaten away over time, so don’t use anything important! A piece of steel rebar is inexpensive and works well. Since the side of the item facing the anode will be cleaned faster, you may want to connect multiple anodes together with copper or steel wire or use a piece of sheet steel bent around the item you’re cleaning to make the process more efficient.
• Nonreactive Container: A plastic storage bin or bucket is perfect. It needs to be large enough to hold both the tool and the anode without touching.
• Twine or Plastic Clamps: Used to suspend the tool and anode in the water.

The beauty of the process is that it gets into places such as splined hubs that are near impossible to get into with mechanical means.  Regards,  -Tom