Usage:
D11N ( 74Z ),
776B ( 6JC ) Tractors;
777B ( 4YC ),
785 ( 8GB ),
789 ( 9ZC ) Trucks
Reference: Service Magazine; June 20, 1988; Page 1; "Troubleshooting Automatic Ether Starting Aid" on D11N, 776B Tractors and 777B, 785, 789 Trucks.
The purpose of this article is to emphasize some important points about cold weather operation of the 3500 Family of Engines in the above machines. Cold starting presents the most severe rough combustion conditions. Rough combustion can result in piston scuffing. The following items help minimize rough combustion.
1. Set fuel injector timing to provide the smoothest possible combustion as well as minimize peak cylinder pressure. See the specification in "Additional Prewinter Checks."
2. The automatic ether starting aid system meters ether into the cold engine when cranking. See the reference article for a complete system description and operating information.
Check the ether system on a regular basis to insure it is functional and to be sure the ether bottles contain ether. The rate of ether consumption will vary depending upon the number of starts and the ambient temperature. It is suggested that the check be done at each oil change (or weekly if the machine is frequently started) until a more specific maintenance schedule can be determined. Check to be sure the correct coolant temperature switch (part number 7X5988) is installed.
NOTE: The correct fuel injector timing and the use of the ether starting system are equally important in the prevention of cold start piston scuffing. If one is implemented without the other, piston scuffing may not be avoided.
3. Change the engine crankcase oil to a winter viscosity or a multi-grade oil. The piston warms up faster than the cylinder liner, the engine coolant, and the engine oil. Therefore, the piston-to-liner clearance will be at a minimum just after a cold start. If a heaver oil such as 30W is used, there may not be sufficient oil flow through the piston cooling jets to cool the piston. This may result in piston scuffing.
Correct Cold Starting Procedure Using Automatic Ether Starting Aid System
Use the following procedure to cold start an engine when the ambient temperature is below 10°C (55°F).
1. Start the engine (following the procedure given in the Operation And Maintenance Manual) with the ether starting aid switch in the "automatic" position.
2. Once the engine has started, move the ether starting aid switch to the "manual" position and hold it there for twenty seconds. After this time the engine should be firing evenly and not exhausting white smoke (unburned fuel). If white smoke still appears, move the ether starting aid switch to the "manual" position and hold it there until the exhaust clears.
3. Allow the engine to warm up at low idle for approximately five minutes before operating the machine.
Additional Prewinter Checks
1. Check the fuel injector timing dimension on the engine specification information plate. Make sure is stamped correctly. The correct injector timing dimension follows.
2. Make sure that the engine specification information plate is permanently attached to the cylinder block.
3. Check valve lash settings, fuel injector timing, and rack synchronization. Adjust as required.
4. Check the fuel ratio control setting (load level limit) and adjust if necessary. See the procedure in the Service Manual. The correct setting is 2.00 mm (.079").