12210-ZW9-405ZA Honda CYLINDER HEAD (000) *NH8* (Honda Code 6671069). (DARK GRAY)

Table 1
Required Tools    
Part Number     Part Name     Quantity    
1U-5470
or
198-4240     Engine Pressure Group
or
Digital Pressure Indicator     1    
Illustration 1 g00293196
1U-5470 Engine Pressure Group Refer to Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group " for the instructions that are needed to use the 1U-5470 Engine Pressure Group. Refer to Operation Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator " for the instructions that are needed to use the 198-4240 Digital Pressure Indicator .
Check the Air Filter Change Indicator Group on the air inlet for a reading of the restriction.
Inspect the engine air cleaner inlet and ducting in order to ensure that the passageway is not blocked or collapsed.
Check for dirt tracks on the clean side of the engine air cleaner element, the air inlet hose, and the clamps. If dirt tracks are observed, contaminants are flowing past the engine air cleaner element, the seal for the air cleaner, and/or the air inlet hose.
Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element.
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.
Use the differential pressure gauge of the 1U-5470 Engine Pressure Group or the 198-4240 Digital Pressure Indicator .
Illustration 2 g01176673
Air inlet system (typical example) (1) Turbocharger (2) Air Inlet Piping (3) Test location (4) Air cleaner
Connect the vacuum port of the differential pressure gauge to the test location (3). Test location (3) can be located anywhere along air inlet piping (2) after engine air cleaner (4) but before turbocharger (1) .The air flow through a new engine air cleaner element must not have a system restriction of more than the following amount: Maximum restriction ... 3.7 kPa (15 inch of H2O)The air flow through a used engine air cleaner may have an additional restriction. The air flow through a plugged engine air cleaner will be restricted to some magnitude. In either case, the restriction must not be more than the following amount: Maximum restriction ... 6.2 kPa (25 inch of H2O) Maximum restriction for RLG engines ... 7.5 kPa (30.1 inch of H2O)Exhaust Restriction
Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Excessive idling can cause the muffler to plug. A plugged muffler will lead to an increase in exhaust back pressure. Operating the engine in extremely cold conditions may cause the muffler to plug. One indication of a plugged muffler is poor engine response.Exhaust Back Pressure for Mufflers
Back pressure is the difference in the pressure between the exhaust and the atmospheric air.
Table 2
Tools Needed    
Part Number     Part Name     Quantity    
1U-5470
or
198-4240     Engine Pressure Group
or
Digital Pressure Indicator     1    
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 different