Cat D4 Part 2

Reassembly
  • Here is the culprit that started it all. The valves had about .020" lash, standard rod and main bearings on a .020" undersize crank. It appeared to have been run in this condition. The cacophony must have been startling to behold. Three of the valves were stuck when I disassembled the engine. It is no wonder it did not run.
  • Here the pony motor displays her violated parts. I had the crank ground to .030" under and installed new .030" under bearings. The cylinders were bored to .030" oversize and fitted with good used pistons and new piston rings. The rods were fitted with new pins and bushings and the big-ends were machined back to round. New valves and good used guides were installed. The cam shaft and gears were in good order.
  • Here the pony motor is being reassembled with proper fitting parts. It should run much quieter than it did when it last ran many years ago. The cost of the overhaul and the time spent waiting for parts for the pony was probably twice that of the diesel which needed only a few replacement parts.
  • The newly rebuilt pony is installed on the rebuilt diesel engine. Installing the pony with the diesel engine on blocks on the floor made it a cake walk compared to the process of removing it when the diesel was still in place in the tractor.
  • A hacked hole in the dash panel must have been cut to access the belt pulley for the electric start of the pony motor. I had cleaned it up considerably with an angle grinder. It looked pretty awful before. I am sure that many HT4 Traxcavators have had this same emergency operation because of the tremendous amount of work it would take to remove the dash panel or to remove the starter assembly just to change the belt.
  • The raised section of the panel provided a form for a section of sheet metal I clamped to it. While heating the sheet, I hammered it down to make a nearly matching section.
  • A couple of 1/4-20 machine screws will attach the cover. Not perfect, but it is only a tractor and it does look much better than the original ragged hole.
  • Amid a mass of chain and cable, the engine is about to be hoisted back into place.
  • The engine is working its way home.
  • Here the engine is seen snuggling back into bed.
  • Sporting all new valves and awaiting the push rods and rocker arm assembly, the head has been torqued to 140 and 70 ft. pounds. Reconditioned injectors are In place. Needing to take some time away from the project, I plugged all openings to keep out the mice out while I was away.
  • This is a view of the pony motor with its accessories installed. It too is rather pretty.
  • The refurbished dash panel, sporting new gauges is installed.
  • For about 20 years 15 gallons of old fuel had incubated a lot of microbes and settled their deposits on the bottom of the fuel tank. Here the emptied seat fuel tank is lifted out to be cleaned.
  • Several tie-down straps were used to secure the seat tank to the wheel of my JD B tractor. About a quart of laundry detergent and 15 gallons of hot water were put into the tank and taken for a half-mile ride. Several subsequent rinses with hot water, with the filler cap removed, dumped out the sludge very nicely.
  • The radiator and hydraulic pump assembly are loaded onto a rack on the back of the tractor. The radiator was given a pressure wash with hot water to clear out a lot of debris. I made this handy rack for the back of the tractor years ago to transport four 55 gallon drums of silage to feed my small herd of beef cattle. I gave up the beef hobby long ago but this rack has proven to be a very handy rig for all sorts of hauling.
  • Following a tip I read about on the forum of the Antique Caterpillar Machinery Owners Club, I fastened a section of inner tube over the tank filler opening with a large hose clamp and inflated it to about an "A" cup. The filter housing, transfer pump and the injectors were all easily purged of air by the fuel in the tank under moderate pressure.
  • My son Scott is driving the Cat out of the shop on pony motor power so we could start the diesel engine outside.
  • Here the diesel makes its first shot at running. After being dormant for 20 years and after a rebuild---and after some false starts she ran beautifully.
  • Here I am with a satisfied grin while taking her out for here first run. The trial run confirmed with a lot of relief that the steering clutches were free and that the brakes were in good working order. Note the still locked-up links in the track.
  • A general clean up with a pressure washer makes the Cat look good even without new paint. Oil pressure problems make it necessary to drop the pan to correct an erratic oil pressure valve. Just when it was looking so close to being finished. At least the heavy grill, belly pans and the hydraulic system had not yet been installed.
  • This is the temporary end of Part 2 which is still under construction. More will be added as progress continues. This Cat project is a fine example of "Project Creep". It all started intending to simply overhaul the pony motor. Work on the pony motor was postponed until after it was determined that the diesel engine was worth fixing. Then there was a rush to locate the pony motor parts to complete the job. Click here to go back to the home page.