Use clean diesel fuel for washing the parts. Disassemble one nozzle at a time to prevent mixing of mating parts. Exercise care to prevent damage to nozzle parts. Inspect and clean all parts as they are disassembled. Carbon may be scraped from the outside of the nozzle, but be careful not to mar the edges of the holes (orifices). When cleaning fluid is used to clean the nozzle parts, dip the parts in diesel fuel immediately after cleaning. This will prevent moisture from the hands from marring the highly polished surfaces.

Reaming tools and special drills are provided for cleaning spray nozzle holes. No drills other than those recommended by the manufacturer should be used. The drills are hand-operated, using a cleaning needle that is held in place by a small chuck, called a pin vise (fig. 5-45). In performing reaming operations, remove only the foreign matter; be particularly careful not to burr the metal.

WARNING

Diesel fuel is a hazardous material. Avoid prolonged skin contact and wear goggles. Keep fire and flame away. Dispose of waste material and cleaning rags as hazardous waste. For more information, see OPNAVINST 4110.2, Hazardous Material Control and Management.

Q31. When should water be drained from the fuel system?

Q32. What is the first requirement when disassembling an injector for cleaning?

GENERAL TROUBLESHOOTING

LEARNING OBJECTIVE: Describe general troubleshooting techniques used in the maintenance of a diesel fuel system.

Figure 5-45. - Cleaning injector spray nozzle holes.

When troubleshooting a diesel engine, keep in mind that problems associated with one make and type of engine (two-stroke versus four-stroke) may not occur exactly in the same way as in another. Specifically, particular features of one four-stroke-cycle engine may not appear on another due the type of fuel system used and optional features on that engine. Follow the basic troubleshooting steps listed below before rolling up your sleeves and trying to pinpoint a problem area.

1. Obtain as much information from the operator as possible concerning the complaint.

2. Analyze the problem in detail first, beginning with the smallest and simplest things.

3. Relate the problem symptoms to the basic engine systems and components.

4. Consider any recent maintenance or repair job that might tie into the problem.

5. Always double-check and think about the problem before disassembling anything.

6. Solve the problem by checking the easiest and simplest things first.

7. If possible, use the special tools and diagnostic equipment at your disposal to verify acomplaint and pinpoint the general area.

8. Determine the cause(s) of the problem and carry out the repair.

9. Operate the engine and road test the vehicle to confirm that the problem is corrected.

EXHAUST SMOKE COLOR

One of the easiest methods to use when troubleshooting an engine for a performance complaint is to monitor the color of the smoke coming from the exhaust stack visually. There are four basic colors that may exit from the exhaust system at any time during engine operation - white, black, gray, or blue. The color of the smoke tips you off to just what and where the problem might lie.

White smoke is generally most noticeable at engine start-up, particularly during cold conditions. As the combustion and cylinder temperatures increase during the first few minutes of engine operation the white smoke should start to disappear which indicates the engine is sound. However, if the white smoke 5-52