930106-0500 Tohatsu NUT

Measurement Of Pressure In Inlet Manifold
Table 1
Tools Needed    
Part Number    Part Description    Qty    
1U-5470     Engine Pressure Group     1    The efficiency of an engine can be checked by making a comparison. Compare the pressure in the inlet cover and the information in the Technical Marketing Information (TMI).This test is used when there is a decrease of horsepower from the engine, yet there is no actual sign of a problem with the engine.The correct pressure for the inlet manifold is also given in the Technical Marketing Information (TMI), "Fuel Setting and Related Information". These standards are established under the following conditions:
96 kPa (29 inches of Hg) dry barometric pressure
29°C (85°F) outside air temperature
35 API rated fuelAny change from these conditions can change the pressure in the inlet manifold. The outside air may have a higher temperature and a lower barometric pressure than the values that are given above. This will cause a lower inlet manifold pressure measurement than the pressure in the TMI. Outside air that has both a lower temperature and a higher barometric pressure will cause a higher inlet manifold pressure measurement.A difference in fuel density will change horsepower (stall speed) and boost. If the fuel is rated above 35 API, the pressure in the inlet manifold can be less than the pressure that appears in the TMI. If the fuel is rated below 35 API, the pressure in the inlet manifold can be more than the pressure that appears in the TMI. BE SURE THAT THE AIR INLET OR THE EXHAUST DOES NOT HAVE A RESTRICTION WHEN YOU ARE MAKING A CHECK OF THE PRESSURE.
Illustration 1 g00557590
Pressure Test Locations (A) Plugs
Illustration 2 g00295554
1U-5470 Engine Pressure Group The 1U-5470 Engine Pressure Group can be used to check the pressure in the inlet manifold.The 1U-5470 Engine Pressure Group has a gauge that indicates pressure inside the inlet manifold. Refer to Special Instructions, SEHS8907 which is included with the engine pressure group for complete instructions.Measurement Of Exhaust Temperature
Table 2
Tools Needed    
Part Number    Part Description    Qty    
1U-8865     Infrared Thermometer     1    When the engine runs at low idle, the temperature of an exhaust manifold port can indicate the condition of a unit injector.A low temperature indicates that no fuel is flowing to the cylinder. An inoperative unit injector pump could cause this low temperature.A very high temperature can indicate that too much fuel is flowing to the cylinder. A malfunctioning unit injector could cause this very high temperature. Use the 1U-8865 Infrared Thermometer to check this exhaust temperature. You can find operating instructions and maintenance instructions inside the Operator's Manual, NEHS0510, "1U-8865 Infrared Thermometer".Air-to-Air Aftercooled Systems
Table 3
Tools Needed    
Part Number    Part Description    Qty    
FT-1984     Air-to-Air Aftercooler Testing Group     1    
FT-1438     Dynamometer Testing Aftercooler     1    Visual Inspection
Inspect the following components of the air-to-air aftercooler system:
all lines
all hoses
all gasket jointsMake sure that the constant torque hose clamps are tightened to the correct torque. Check the truck manufacturer's specifications for the correct torque. Check the welded joints for any cracks. Check the brackets for correct positioning. Also, make sure that these brackets are in good condition. Use compressed air to clean any debris or any dust from the aftercooler core assembly. Inspect the aftercooler core assembly's fins for the following conditions:
damage
debris
salt corrosionUse a stainless steel brush to remove any corrosion. Make sure that you use soap and water.
Pressurized air can cause personal injury. When pressurized air is used for cleaning, wear a protective face shield, protective clothing, and protective shoes.
Note: When air-to-air aftercooler parts are repaired and air-to-air aftercooler parts are replaced, a leak test should be completed. Do not use winter fronts and shutters with aftercooler systems. Winter fronts can only be used on certain truck models. The jacket water pumps on these models will overheat before the air temperature of the inlet manifold becomes excessive. These truck models use special alarms or other indicators. These instruments warn the operator about an engine overheating. Check with the manufacturer about the use of both winter fronts and shutters.Air System Restriction
Periodically, take pressure measurements at the turbocharger outlet and at the inlet manifold. The air lines and the cooler core must be inspected for internal restriction under both of the following conditions:
The air flow is at a maximum level.
The total of the air pressure drop of the charged system has exceeded the following value: 13.5 kPa (4 Inches Hg)If a restriction is discovered, proceed with the f