HOOD ASSEM. 8P4657 - Caterpillar

Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts.When working on an engine that is running, avoid contact with hot parts and rotating parts.
If the exhaust is not equipped with a back pressure tap, the following procedure may be use in order to install a pressure tap. Refer to Truck Engine News, SEBD6729, "Measuring Exhaust Back Pressure" for measuring the back pressure at a proper test location.Use the differential pressure gauge of the 1U-5470 Engine Pressure Group or the 198-4240 Pressure Indicator Tool Gp in order to measure back pressure from the exhaust. Use the following procedure in order to measure back pressure from the exhaust:High Idle Plugging Test
Note: Do not try to burn out a plugged muffler. The muffler can become severely overheated. This will cause other system components to fail.
Inspect the system components for any noticeable damage that would cause a restriction.
Connect the pressure port of the differential pressure gauge to test location. Refer to Truck Engine News, SEBD6729, "Measuring Exhaust Back Pressure" for measuring the back pressure at a proper test location.
Leave the vacuum port of the differential pressure gauge open to the atmosphere.
Start the engine. Run the engine in the no-load condition at high idle until the engine reaches normal operating temperature.
Record the value.
Multiply the value from Step 5 by 1.8.
Compare the result from Step 6 to the value that follows. Back pressure from the exhaust must not be more than the following amount: Maximum back pressure for engines with a standard muffler ... 10.0 kPa (40 inch of H2O)Maximum back pressure for engines with a catalytic converter/muffler ... 12.4 kPa (50 inch of H2O)If the maximum back pressure is within the allowable limits, refer to Troubleshooting, "Low/Power/Poor or No Response to Throttle".If the back pressure exceeds 12.4 kPa (50 inch of H2O), replace the muffler.
Illustration 3 g01403351
Exhaust system (typical example)
(1) Turbocharger
(5) Test location
(6) Muffler
(7) Exhaust piping Full Load Test
Note: Do not try to burn out a plugged muffler. The muffler can become severely overheated. This will cause other system components to fail.
Check the arrangement number of the engine and verify that all components are correct. Note: Run the vehicle on a dyno up to 30 minutes in order to reach operating temperature. Monitor all of the engine components for any signs of overheating.
Measure the back pressure at a full load and full speed.
Record the results.
The back pressure for the catalytic converter/muffler is at 12.4 kPa (50 inch of H2O).
Replace any components that have been proven damaged. Exhaust Back Pressure for Diesel Particulate Filters (If Equipped)
High Idle Plugging Test
Illustration 4 g01403354
diesel particulate filter (typical example)
(8) Inlet section
(9) Catalyst section
(10) Filter section
(11) Outlet section
(12) Test location
(13) Tee fitting
(14) Copper tubing
(15) Thermocouple Note: Limit the idle time of the engine to 20 minutes. If large quantities of soot are accumulated in the diesel particulate filter,