75909 Mercury GASKET

Introduction
Do not perform any procedure in this Special Instruction until you read this information and you understand this information.This Special Instruction contains procedures for cleaning the heat exchangers that are listed in Table 1. This instruction also covers the usage of the 248-6745 Bars (service tool) and 162-7120 Pins that are listed in Table 2.
Table 1
Heat Exchangers for the 3500B Marine Engines    
Part Number     Engine Model    
249-1021     3508B
3512B    
245-9841     3516B    
Table 2
Required Service Tools    
Part Number     Description     Qty    
(248-6745)     Bars     2    
(162-7120)     Pin     2    Unless the water system for the heat exchanger is sealed, debris may enter the water. Examples of debris are seaweeds, wood chips, mussels, barnacles, etc. Debris in the water will reduce the efficiency of the heat exchanger. This can result in excessive water temperatures that may require an engine shutdown. Preventing debris from entering the water and/or filtering the water will reduce the need for cleaning.The quality of the water can also affect the performance of the heat exchanger. Buildup such as sediment and scale reduces the heat transfer characteristics of the plates. The pressure differential of fluids that flow through the heat exchanger is increased. Corrosion can occur beneath the buildup. The buildup can result from sources that are organic or inorganic.The combination of these two factors indicate that the heat exchanger requires cleaning:
Inability of the heat exchanger to maintain the desired temperatures
Increased pressure differential of the fluids that flow through the heat exchangerFrequently record these parameters during operation if a concern is present:
Aftercooler inlet water temperature
Inlet manifold air temperature
Jacket water coolant temperature
Pressure differential of the fluids that flow through the heat exchangerCompare the data to previously recorded data. Clean the heat exchanger, if necessary.Ensure that the engine will not operate when this maintenance is performed. Attach a "DO NOT OPERATE" tag or similar warning tag to the controls before performing maintenance or repairs.Draining the Cooling System
Note: Refer to Operation and Maintenance Manual for information on the interval for changing the coolant.
Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Note: If the heat exchanger is hot, wait until the temperature of the heat exchanger is reduced to approximately 40 °C (104 °F) before proceeding.
Prepare a suitable container for the coolant.Note: For complete draining, all of the circuits of the heat exchanger must be ventilated. If the installation does not have vent valves, remove the filler caps from the expansion tanks.
Drain the heat exchanger.Removal and Installation of the Heat Exchanger (If Required)
It is not necessary to remove the heat exchanger in order to clean the plates.Do not remove the heat exchanger unless a complete disassembly of the heat exchanger is desired. Breaking the seals on the rear of the heat exchanger will require a complete disassembly in order to remove collar (6). A complete disassembly is also required in order to replace liner (8). Refer to Illustration 1.
Illustration 1 g01153325
Heat exchanger (1) Tightening bolts (2) Washer (3) Spacer (4) Front frame (5) Spacer (6) Collar (7) Rear plate (8) Liner (9) Washer (10) Bolt
Illustration 2 g01162242
The heat exchanger will require removal if there is a leak at location (A) or at location (B).Removal Procedure
Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. To help prevent possible injury, turn the start switch off when changing fuel filters or water separator elements. Clean up fuel spills immediately.
Before removing the heat exchanger, stop the engine. Ensure that the engine will not start during this procedure.
Shut off the fuel supply valve to the engine.