UBUC Maintenance Documentation

This club exists to provide for its members facilities, opportunity and training for underwater exploration, science, and sport.

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Engine Service

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Responsible Officers

Procedure Log

Date Member Supplier Cost Comment
2014-11-11 Dmitro Khroma 200.00 Marine engineers fee for overseeing course
2013-11-11 Tim Walsh 150.00 Budget estimate for engine service comes from sum of part costs=150
2013-11-11 Tim Walsh 180.00 Marine engineers fee for overseeing course=180
2012-01-01 Tim Walsh 754.00 Engines serviced by Samspeed neither worked on return wouldn't use Samspeed again


, (2018-04-05), (2018-04-05)

Required Items

Item Attributes In Stores? Replacements to buy
101 Marine Grease
    10mm slot screwd
      24C Marine Grease
      • newvalue = 10.80
      Block of wood
        Boat Spark Plugs
        • NGKPartNo = NGK BR7HS-10
        • gap = 0.9-1.0mm
        • newvalue = 2.85
        • torque = 27Nm
        true 2
        Carb Service Kit
        • MercuryPartNo = 853780A1
        • PartListRef = 24-3
        • TohatsuPartNo = 345-87122-0
        • newvalue = 45.66
        true 1
          Engine Comp Guage
            Engine Degreaser
            • newvalue = 4.99
            Engine Tuner
            • newvalue = 15.00
            Engine muffs
            • newvalue = 10
            Fuel Pump Gasket
            • MercuryPartNo = 27-853702008
            • PartListRef = 5-2
            • TohatsuPartNo = 346-04901-0
            • newvalue = 3.05
            false 1
            Gasket Scraper
              Gear Oil
              • newvalue = 9.5
              • type = API GL-5: SAE#80 to #90
              • volume = 420ml
              true 1
              Gear oil pump
              • newvalue = 22.08
              Marine Grease Gun
                Oil Container
                  Oil vent gasket
                  • MercuryPartNo = 8M0082880
                  • PartListRef = 14-4
                  • TohatsuPartNo = 332-60006-0
                  • newvalue = 2.49
                  • thickness = 1.2mm
                  true 2
                  Prop split pin
                  • MercuryPartNo = 18-8150264
                  • PartListRef = 15-23
                  • TohatsuPartNo = 951503-0325
                  • length = 34mm
                  • newvalue = 2.68
                  • thickness = 2.7mm
                  true 1
                  • diameter = 2.4mm
                  Small adjustable
                  • nutsize = 22mm
                  Small peen Hammer
                    Spark Jump Tester
                    • newvalue = 9.95
                    Spring Pin
                    • MercuryPartNo = 17-952189
                    • PartListRef = 16-19
                    • TohatsuPartNo = 951403-0312
                    • length = 12mm
                    • newvalue = 2.95
                    • thickness = 3mm
                    true 1
                    Starter rope
                    • MercuryPartNo = 50-8126391
                    • PartListRef = 11-1-21
                    • TohatsuPartNo = 345-05013-1
                    • length = 205cm
                    • newvalue = 21.6
                    • thickness = 4mm
                    true 1
                        Thermostat Gasket
                        • MercuryPartNo = 27-853702005
                        • PartListRef = 1-14
                        • TohatsuPartNo = 346-01032-0
                        • newvalue = 5.69
                        true 1
                        Torque Wrench
                          Water Heater
                            Water pump kit
                            • MercuryPartNo = 853792T01
                            • PartListRef = 24-9
                            • TohatsuPartNo = 361-87322-0
                            • newvalue = 64.11
                            true 1
                            • type = unleaded
                              pan or beaker
                                piece of string

                                  Check Tools

                                  Perform the Tool box Insp. as these tools are required during the engine service. Tools Small peen Hammer , multimeter , Gasket Scraper and 10mm slot screwd are also vital.

                                  Pre-Service Tasks

                                  This step involves turning the engine over so it must be connected to a cooling water supply using the Engine muffs to prevent damage to the water pump impeller Keep clear of the prop in case the engine hasn't been drained of fuel and starts. Remove the Boat Spark Plugs and inspect for condition against the Spark Colour Chart ( ) Using the Spark Jump Tester check the spark jump on each HT lead in turn. The spark should jump at least 2cm and its shape should be straight with a violet blue color. A red or curved spark may indicate a coil defect. Using the Engine Comp Guage measure and record the compression of both engine cylinders they should be within 15% of each other. Clean the engine thoroughly using a Engine Degreaser .

                                  Set up

                                  Mount the engine securely on its engine trolley . If the Clamp Pad fall off then replace and tighten onto the ball of the Small peen Hammer to fix. Remove Dead mans handle It is vital that the engine is not accidently started during this operationRemove Motor Cover Engine Manual ( page = 54 , ), Seamanship Manual ( pg = 75 , )

                                  Inspect Anodes

                                  Engine Manual ( page = 54 , ) SELCO ( page = 2-28 , )Inspect Trim Tab Anode and Bracket Anode if they've degraded more than 30% then replace. Using tool multimeter verify an electrical connection between each anode and the engine body.

                                  Grease Propeller Shaft

                                  SELCO ( page = 2-28 , )Remove and discard Prop split pin Using Small adjustable with Block of wood between the propeller and anticavitation plate to stop the propeller turning undo Propeller Nut . Slide parts Propeller Washer and Propeller Stopper from the splines of the Propeller shaft . Remove Propeller . Remove Thrust Hub noting its orientation. Clean and grease the Propeller and Propeller shaft using 24C Marine Grease . Reassemble using Torque Wrench to torque Propeller Nut to its specification.

                                  Verify Thermostate

                                  SELCO ( section = 5-27 , )Undo Bolt . Remove Thermostat Cap and using Gasket Scraper remove and discard Thermostat Gasket . Using a suitable Water Heater the thermostat suspended in a pan or beaker of water suspended on a piece of string clamped in the thermostat valve. Using a Thermometer Verify that Thermostat Opens and drops at the correct temperature. Reassemble using 101 Marine Grease

                                  Check Fuel Pump

                                  Unbolt the Fuel Pump. Replace item Fuel Pump Gasket . Check fuel pump is not leaking

                                  Service carb

                                  SELCO ( section = 3-14 , ) Engine Parts List ( page = 11 , ) SELCO ( section = 3-20 , )Undo the clip disconnect Fuel Pipe . Disconnect the Choke link rod . Remove the 4 Carb Nuts and withdraw the carbetrettor. Undo the Drain Screw to drain fuel from the carb and replace the Drain Screw Seal Undo the 4 Carb bowl screws . Drop the Float Chamber down. Replace the parts in Carb Service Kit . carefully turn the Adjust Screw in (clockwise) counting the turn until it gently reaches its end. Record the number of turns taken and then remove it. Clean and dry all parts with CarbCleaner and reassemble.

                                  Replace Fuel Line

                                  If any of the fule line is old it should be replaced using Fuel Line

                                  Replace Gear Oil

                                  Ensure the engine is upright. Using the 10mm slot screwd Loosen the top vent Oil vent plug . Place an Oil Container under the skeg remove the lower fill Oil vent plug to let the oil drain. Look for any metal particals on the magnet. Check the Gear Oil for water. If significant metal or water is present then the gearbox must be disassembled and inspected. Replace the two Oil vent gasket . Using the Gear oil pump Fill the gearbox with 420ml of Gear Oil from the lower vent plug Engine Manual ( page = 57 , ), then replace the top to hold the oil in through suction then replace lower.

                                  Remove lower leg

                                  SELCO ( section = 7-15 , )Move the engine into forward gear. Using Punch and Small peen Hammer drive out Spring Pin remove the 4 bolts and washers Gear box bolts Pull down on the gearbox and pull the driveshaft and seperate it from the exhaust housing. Guide the gear shift rod and driveshaft out of the exhaust housing.

                                  Replace Water pump

                                  SELCO ( section = 5-17 , )Remove the bolts Water pump bolts replace the parts in the Water pump kit and assemble gaskets and bolts with 101 Marine Grease


                                  SELCO ( section = 2-40 , ) SELCO ( section = 6-5 , ) SELCO ( section = 6-59 , )During combustion carbon is deposited within the combustion chamber there are various ways of removing it, this procedure uses a chemical method. Start the engine up and use a can of Engine Tuner into the carb intake of a running engine.

                                  Replace Starter Cord

                                  Disconnect the Starter Lock Rod . Remove the two Bolts and the Bolt at the back of the starter unit. Lift off the Recoil Starter . Replace the Starter rope SELCO ( section = 10-9 , )

                                  Tune up

                                  Remove and replace the two Boat Spark Plugs checking they have the correct gap before re-installing. SELCO ( section = 2-57 , )With the engine set up and running, check and adjust ignition timing Timing Link Rod . Then adjust the Throttle limit so that the engine idles at 850 RPM SELCO ( section = 2-19 , )measured using a Tacheometer .


                                  Using the Marine Grease Gun lubricate all grease nipples and apply grease to all sliding surfaces