C8.7 Marine Engines Caterpillar

Air Inlet and Exhaust System - Inspect

Usage:

C8.7 CS7

Safety Precautions

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Do not operate or work on this engine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility.

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Keep hands clear of fan and belts while engine is running.

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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.

Specifications

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Table 1
Air inlet Vacuum Pressure Specifications
Test location is anywhere on the air inlet pipe between the air filter and the turbocharger
	Maximum Vacuum Pressure
For a used engine air cleaner	5 kPa (20 inch of H₂O)
For a new engine air cleaner	3 kPa (12 inch of H₂O)

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Table 2
Exhaust Outlet Pressure Specifications
Test location is anywhere on the exhaust pipe between the exhaust manifold and the muffler
Maximum pressure is 10 kPa (40 inch of H₂O)

Introduction

This inspection checks the inlet air system for restrictions and checks the exhaust system for excessive back pressure.

Required Tools

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Table 3
Required Tools
Quantity	Part Number	Part Name
1	1U-5470 or 198-4240	Engine Pressure Group or Digital Pressure Indicator

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 Pressure Indicator Tool Gp " for the instructions that are needed to use the 198-4240 Pressure Indicator Tool Gp.

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Illustration 1	g02571852
Tooling (A) 198-4240 Digital Pressure Indicator Gp

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Table 4
Most Recent Required Tools
Tool	Item	Qty	Part No	Description
A				Digital Pressure Indicator Gp
	A1	1	198-4240	Digital Indicator
	A2	1	198-4237	Pressure Sensor Gp (0 to 3,445 kPa (0 to 500 psi))
	A2	1	198-4238 ⁽¹⁾	Pressure Sensor Gp (0 to 34,450 kPa (0 to 5,000 psi))
	A2	1	198-4239	Pressure Sensor Gp (0 to 41,368 kPa (0 to 6,000 psi))
	A2	1	251-9600 ⁽²⁾	Pressure Sensor Gp (0 to 68,900 kPa (0 to 10,000 psi))
	A3	1	198-4236	Adapter Cable As

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^( 1 )	This sensor must be purchased separately and is not included in the 198-4240 Digital Pressure Indicator Gp
^( 2 )	This sensor can only be used on large diameter pressure taps like 6V-3965 Fitting .

Test Preparation

Remove all covers that obscure the air inlet and exhaust systems.

Test Procedures

Air Inlet Restriction

There will be a reduction in the performance of the engine if there is a restriction in the air inlet system or the exhaust system.

Inspect the engine air cleaner inlet and ducting in order to ensure that the passageway is not blocked or collapsed.

Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element.

Check for dirt tracks on the clean side of the engine air cleaner element. If dirt tracks are observed, contaminants are flowing past the engine air cleaner element and/or the seal for the engine air cleaner element.

Use the differential pressure gauge of the 198-4240 Digital Pressure Indicator Gp .
1. Remove air filter change indicator (1) .
1. Connect the vacuum port of the differential pressure gauge to the air filter change indicator port.
1. Leave the pressure port of the differential pressure gauge open to the atmosphere.
1. Start the engine. Run the engine in the no-load condition at high idle.
1. Record the value.
1. Multiply the value from Step 4.e by 1.8.
1. Compare the result from Step 4.f to the appropriate values that follow.

The air flow through a used engine air cleaner may have a 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 ... 5 kPa (20 inch of H₂O)

The air flow through a new engine air cleaner element must not have a restriction of more than the following amount:

Maximum restriction ... 3 kPa (12 inch of H₂O)

Install the air filter change indicator after performing the test.

Exhaust Restriction

Back pressure is the difference in the pressure between the exhaust at the outlet elbow and the atmospheric air.

Use the differential pressure gauge of the 198-4240 Digital Pressure Indicator Gp in order to measure back pressure from the exhaust. Use the following procedure in order to measure back pressure from the exhaust:

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Illustration 3	g03702503
Rear view of the engine (3) Plug

Remove plug (3) from the optional sea water-cooled exhaust riser if equipped.

Connect the pressure port of the differential pressure gauge to the port where plug 3 was removed.
The test location can be located anywhere along the exhaust piping after the turbocharger but before the muffler.