12115 3 Mercruiser DECAL, ROCKER COVER (3.0L)

If no oil pressure is indicated, STOP the engine. The engine will be damaged from operating without oil pressure.
Engine oil pressure - This gauge indicates the pressure of the engine oil. This pressure will be highest after a cold engine is started. The pressure will decrease as the engine warms up. The pressure will increase when the engine rpm is increased. The pressure will stabilize when the engine rpm and temperature are stable.If the load is stabilized but the engine oil pressure fluctuates, perform the following procedure:
Remove the load.
Reduce the engine speed to low idle rpm.
Check the oil level. Maintain the oil level between the "ADD" and "FULL" marks on the "LOW IDLE" side of the oil level gauge (dipstick).
Inspect the lubrication system for leaks.
Engine Oil Temperature - This gauge indicates that the engine oil temperature after the oil has passed through the oil cooler.Engine oil performs several functions: keeping the engine clean, preventing rust and corrosion, acting as a coolant and reducing friction and wear. The oil cooler transfers heat from the oil to the engine jacket water. Oil temperature that is higher than normal indicates a problem with the lubrication system and/or the cooling system. Excessive oil temperature can adversely affect the cylinder heads, cylinder liners, pistons, and crankshaft bearings.
Jacket water coolant temperature - This gauge indicates the temperature of the engine coolant at the outlet for the jacket water. The temperature may vary according to the load. Do not allow the temperature to exceed the boiling temperature of the pressurized cooling system.The sensor for jacket water coolant temperature must be submerged for the correct detection of the temperature. If the engine is operating above the normal temperature range, perform the following procedure:
Reduce the load and/or the engine rpm.
Inspect the cooling system for leaks.
Determine if the engine must be shutdown immediately or if the engine can be cooled by reducing the load and/or rpm.
System voltage - This gauge indicates the voltage of the electrical system. Normally, the system has 24 V.
Fuel pressure - This gauge indicates fuel pressure to the fuel injection pump from the fuel filter. A decrease in fuel pressure usually indicates a dirty fuel filter or a plugged fuel filter. As the fuel filter becomes plugged, there will be a noticeable reduction in the engine performance.
Exhaust temperature - This gauge indicates the exhaust temperature at the exhaust inlets to the turbochargers. The two exhaust temperatures may vary slightly because of variations of the sensitivity of the two thermocouples. The "LH/RH" switch on the instrument panel is used for toggling between the left side and the right side exhaust temperature.The exhaust temperatures at the exhaust inlets to the turbochargers provide a good indication of engine performance. For engines with dry exhaust manifolds, the temperatures are representative of the actual temperatures of the valves. Monitor this parameter frequently.If the recommendations for the engine installation, the rating, and engine maintenance are followed, most engines will operate at normal or below the normal limit.
Severe damage to the engine can result if the exhaust temperature at the inlet to the turbocharger exceeds the extreme limit.
Table 1
Temperature Limits for the Exhaust Inlet to the Turbocharger
Rating (1) Normal Limit Extreme Limit
A, B, C 650 °C (1202 °F) 680° C (1256° F)
(1) For the rating definitions, see this Operation and Maintenance Manual, "Engine Rating Definitions".Pyrometer - The pyrometer displays the temperature of the exhaust for the exhaust port of each individual cylinder.The exhaust port temperatures are a good indication of the condition of the cylinders. The displayed temperature is slightly lower than the actual temperature in the cylinder because of the constant flow of exhaust gas past the thermocouple. For engines with dry exhaust manifolds, the exhaust port temperatures are lower than the temperatures at the inlet to the turbochargers.Guttering of valves can be diagnosed with the exhaust port temperature. The ability to diagnose this problem may help to prevent more damage that could cause further downtime with a higher repair cost.During normal operation at rated load, the temperature of the hottest cylinder and the coldest cylinder may be different. The difference may vary by 38°C to 52°C or 68°F to 94°F.Be alert if an exhaust port temperature varies by more than 50°C or 90°F from the average temperature of all the cylinders.Note: If a cylinder exhaust port temperature varies by more than 50° C (122° F), continue to monitor the cylinder temperatures but troubleshooting is not required. If the cylinder temperature increases to 100° C (212° F), cylinder troubleshooting should begin. Refer to Troubleshooting , M0065598 for more information.Perform corrective measures if an exhaust port temperature varies by more than 100°C or 180°F from the average temperature of all the cylinders.The exhaust stack temperature is not a suitable substitute for the exhaust temperature at the inlet to the turbocharger. However, a comparison of the two temperatures can help to assess the performance of the turbocha