11086T Mercruiser EXHAUST ELBOW ASSEMBLY (PORT)

Visual Inspection
Inspect the following parts:
Air lines
Hoses
Gasket joints
Pressurized air can cause personal injury. When pressurized air is used for cleaning, wear a protective face shield, protective clothing, and protective shoes.
Ensure that the constant torque hose clamps are tightened to the correct torque. Check the welded joints for cracks. Ensure that the brackets are in good condition and ensure that the brackets are tight. Use compressed air to clean any debris or any dust from the aftercooler core assembly. Inspect the core fins for the following conditions:
Damage
Debris
CorrosionUse a stainless steel brush to remove any corrosion. Ensure that you use soap and water.Note: When parts of the aftercooler system are repaired, perform a leak test in order to confirm that the repair has been successful.Inlet Manifold Pressure
Normal inlet manifold pressure with high exhaust temperature can be caused by blockage of the fins of the aftercooler core. Clean the fins of the aftercooler core. Refer to "Visual Inspection" for the cleaning procedure.Low inlet manifold pressure and high exhaust manifold temperature can be caused by any of the following conditions:Plugged air cleaner - Clean the air cleaner or replace the air cleaner, as required. Refer to the Operation and Maintenance Manual, "Engine Air Cleaner Element (Dual Element) - Inspect/Clean/Replace".Blockage in the air lines - Blockage in the air lines between the air cleaner and the turbocharger must be removed.Aftercooler core leakage - Visually inspect the aftercooler core in order to identify coolant leakage from the core. Refer to "Aftercooler Core Leakage" topic for the testing procedure.Inlet manifold leak - An inlet manifold leak can be caused by the following conditions: loose fittings and plugs, missing fittings and plugs, damaged fittings and plugs and leaking inlet manifold gasket.Measuring the Air Temperature and Air Pressure Across the Aftercooler
Remove all air leaks from the system to prevent engine damage. In some operating conditions, the engine can pull a manifold vacuum for short periods of time. A leak in the aftercooler or air lines can let dirt and other foreign material into the engine and cause rapid wear and/or damage to engine parts.
Illustration 1 g02646399
Test locations for the aftercooler temperature and pressure measurements (left side engine view)
(1) Port for measurements at outlet of the turbocharger compressor
(2) Ports for measurements at the inlet of the intake manifold (aftercooler air outlet)Perform measurements for pressure and temperature at the locations that are shown Illustration 1. Perform the measurements while the engine is under a normal mode operation. Record the test results in the following Table:
Table 2
Aftercooler Temperature and Pressure Measurements
Parameter 100% Load 75% Load 50% Load
"Compressor Out Pressure" (Inches Hg (ABS))
"Inlet Manifold Pressure" (Inches Hg (ABS))
"Compressor Out Temperature" (°F)
"Aftercooler Air Outlet Temperature" (°F) Compare the results of the test to values that are given in Technical Marketing Information (TMI). Look for similar results. If a large change in the temperature or the pressure differential is noticed, there may be a problem in the aftercooler circuit.If a large change for the pressure differential is discovered, check the air inlet system and the aftercooler circuit for restriction. Perform any necessary repairs. Refer to the topic "Inlet Manifold Pressure" for details that are related to troubleshooting the inlet air system.If a large change for the temperature differential is discovered, check the SCAC cooling system for a problem. Ensure that the aftercooler core is not restricted. If a restriction in the aftercooler core is suspected, refer to the topic "Measuring the Coolant Pressure Across the Aftercooler Core" for details.If a leak in the aftercooler core is suspected, refer to the topic "Aftercooler Core Leakage" for details.Measuring the Coolant Pressure Across the Aftercooler Core
Illustration 2 g06316135
Ports for measurement of the aftercooler coolant pressure (right side engine view)
(3) Outlet port for the aftercooler coolant
(4) Inlet port for the aftercooler coolantPerform measurements for the coolant pressure across the aftercooler core at the locations that are shown Illustration 1. Perform the measurements while the engine is under a normal mode operation.Compare your results to the following specifications that are for a new aftercooler core:These specifications were obtained under the following test conditions:Water flow in the SCAC system ... 79.5 L/min (21 US gpm)Specification for the water temperature at the inlet of the aftercooler core ... 54° to 75°C (129° to 134°F)Note: Ensure that consideration is given for the test conditions during the test.The following specification is for the pressure drop across the aftercooler core:Water pressure differential ... 9.6 kPa (1.4 psi)If the pressure drop across the core is out of specification, clean or replace the aftercooler core.Aftercooler Core Leakage
Typically, a leak from the coolant circuit of the aftercooler core can be found by performing a visual inspection of the core. Perform the following procedure:
Remove the aftercooler cover assembly in order to gain access to the aftercooler core.
Disconnect the coolant lines from the inlet and outlet side of the aftercooler core.
Remove the core from the engine.
Perform a visual inspection of the aftercooler core. Look for a buildup of calcium and scale at the site of the leak. Perform the necessary repairs.If the leak cannot be found through a visual inspection of the core, perform the following procedure: