0306435 JOHNSON SCREW,Cyl.to crankcase

Introduction
This Special Instruction contains procedures that will improve the cold starting capability of 3406E Engines that are used in 621G 623G 627G Wheel Tractor-Scrapers.The original ether system on these machines uses a pulsed flow of ether in order to assist cold starting of the machine. An updated procedure is now available to convert the ether system into a system that uses a continuous flow of ether. The updated ether system allows continuous flow that will improve the cold starting capability of the 3406E Engine.The updated ether starting aid and the adjustments that are performed by the new software will improve the performance of the machine during cold starting.Note: The ether starting aid will be active if the engine oil temperature is below 9 °C (48 °F).Note: Do not press the accelerator pedal while you attempt to start the machine with any of these improvements. If the accelerator pedal is pressed before starting, during starting, or within a few moments after starting, the machine may not start successfully.Do not perform any procedure in this publication or order any parts until you understand the information that is contained in this publication.Safety
Do not attempt to disassemble or assemble this machine until you read and understand the disassembly and assembly instructions. Improper disassembly and assembly procedures could result in injury or death.
Accidental engine starting can cause injury or death to personnel working on the equipment.To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system.Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.
Breathing ether vapors or repeated contact of ether with skin can cause personal injury. Personal injury may occur from failure to adhere to the following procedures.Use ether only in well ventilated areas.Do not smoke while changing ether cylinders.Use ether with care to avoid fires.Do not store replacement ether cylinders in living areas or in the operator's compartment.Do not store ether cylinders in direct sunlight or at temperatures above 49 °C (120 °F).Discard cylinders in a safe place. Do not puncture or burn cylinders.Keep ether cylinders out of the reach of unauthorized personnel.To avoid possible injury, be sure the brakes are applied and all controls are in Hold or Neutral when starting the engine.
Recommended Practices
The battery disconnect switch should be placed in the OFF position when the machine is not being operated. This practice will result in increased life of the battery and improved performance.The ether bottle should be removed if ether will not be required and the temperature will be above 16 °C (60 °F) for an extended period of time. When the ether bottle is removed, replace the cap on the ether valve. Store the ether bottle in a location that is cool and dry.Fluid Recommendations
Ensure that you are using the proper fluids for the environment of the machine. Refer to the following publications:
Operation and Maintenance Manual, SEBU7280, "621 Wheel Tractor Scraper" ALP
Operation and Maintenance Manual, SEBU7281, "623G Wheel Tractor-Scraper"ARW
Operation and Maintenance Manual, SEBU7282, "627G Wheel Tractor-Scraper" AXF
Operation and Maintenance Manual, SEBU7696, "621G Wheel Tractor-Scraper" CEN
Operation and Maintenance Manual, SEBU7511, "623G Wheel Tractor-Scraper" CES
Operation and Maintenance Manual, SEBU7512, "627G Wheel Tractor-Scraper" CEX
Operation and Maintenance Manual, SEBU6250, "Caterpillar Machine Fluids Recommendations"
Operation and Maintenance Manual, SEBU5898, "Cold Weather Recommendations for all Caterpillar Machines"Procedure to Update the Ether System
Table 1
Required Parts    
Part Number     Description     Quantity    
280-2562     Ether Atomizer Gp     1    
3B-6768     Reducer Bushing     1    
239-1134     Ether Starting Valve Gp     1    
230-1434     Fitting As     1    
339-7731     Engine Ratings Electronic Software Gp     1    Procedure
Illustration 1 g01770473
Side view of the inlet manifold for the tractor engine (1) 280-2562 Ether Atomizer Gp (2) 3B-6768 Reducer Bushing (3) Inlet manifold
Illustration 2 g02004400
Top engine view (1) Atomizer (5) Direction of air flow
Disconnect the ether line from the atomizer. Replace the current atomizer with the atomizer (1) and bushing (2). Refer to Illustration 1. Orient the atomizer (1) in order to spray ether against the air flow. Refer to Illustration 2.
Illustration 3 g01771496
(6) 239-1134 Ether Starting Valve Gp
Remove the current valve assembly and the current fitting assembly. These parts will not be reused. Install the ether starting valve group (6) .