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TOHATSU M70C Manual
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TOHATSU M70C Manual

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M70C
Disassembling & Reassembling procedure
TOHATSU Corporation Japan
Service Div.

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Summary of Contents for TOHATSU M70C

  • Page 1 M70C Disassembling & Reassembling procedure TOHATSU Corporation Japan Service Div.
  • Page 2 □M70C Open Packing ～ PDI <Open Packing of carton box ~ PDI> Open the packing Check the carton box breakage and damage surface of the packing before open the carton box. Check the contents Open the carton box and check the contents...
  • Page 3 PDI (abbreviation of elivery nspection) Check and confirm about following items, using Pre-Delivery Inspection Check Sheet. PDI sheet is as next page. CHECK BEFORE OPERATION CHECK DURING OPERATION CUSTOMER DELIVERY CHECK LIST [The procedure before PDI work] It hangs to the stand an outboard motor using a hoist, then tighten transom bolts (It is careful when carrying out hooking of the outboard motor.) Install Tiller handle.
  • Page 4 It becomes the delivery to a customer after all operation checked. *Necessity of the PDI The outboard motors of Tohatsu are produced in a factory and confirm each adjustment by driving before shipment. Temperature or the humidity is different globally by a country and an area. The check before shipping an outboard motor is necessary for these different places.
  • Page 5 TOHATSU OUTBOARD MOTOR Pre-Delivery Inspection Check List 2 and 4-Stroke Models Trained personnel should check that the unit has been pre-delivered in accordance with the relevant Tohatsu Outboard Manual. The following points must be confirmed at pre-delivery and during the water test.
  • Page 6 □M70C Maintenance section Engine <Disassembly> Remove each terminal of harness from the power head. CDI unit harness Charge coil harness Ignition coil harness Lanyard stop switch harness Each ground wire Carburetor and throttle linkage connections Shift linkage connection Throttle and advance arm connection...
  • Page 7 Fuel hose to fuel filter (In side) Pilot hose connection After removing each connection, remove an apron and engine attachment bolts. Remove carburetors and inlet manifold. Loose flywheel nut using special tool (Flywheel Puller kit 3C7-72211-1) Remove flywheel from crankshaft using special tool (Flywheel Puller). Remove oil re-circulation hose.
  • Page 8 Check the balance of crankshaft. Crank shaft Deflection Limit: 0.05mm Inspection of power head cooling water passage Remove thermostat cover and thermostat. Remove cylinder head cover and exhaust cover. Check corrosion and remove clogs and debris from cooling water passage. Check thermostat, replace if the thermostat valve is open even a little at ambient temperature.
  • Page 9 Engine <Assembling> Assembling engine reverse of their disassemble steps. Size x Q'ty 1 st 2 nd Cylinder head M8 x 14 1.2-1.5kg.m 3.0-3.5kg.m Cylinder head cover M6 x 17 0.47-0.64kg.m Exhaust cover M6 x 14 0.4-0.6kg.m 0.8-1.0kg.m Intake manihold 0.4-0.6kg.m 0.8-1.0kg.m Air silencer 0.27-0.36kg.m...
  • Page 10 Check the position of lower main bearing located bottom of crankshaft. Put certainly crankshaft thrust washer in the cylinder grooves. (2) Apply sealing gasket to crank case Degrease crank case and cylinder mating faces. Apply sealing gasket (LOCTITE 518) to crankcase’s mating surface.
  • Page 11 (3) Check the connection of oil re-circulation hose. (4) Check the position of each linkage such as original position. Choke linkage connection Throttle and advance arm connection Shift linkage connection Carburetor and throttle linkage connection (5) Check the harness connection such as original position Each grand wire Lanyard stop switch harness Ignition coil harness...
  • Page 12 Bracket <Disassembly> Tilt up the outboard motor. Remove the shift lever shaft from bottom cowl. Remove the spring pin of shaft rod joint using spring pin tool. Remove the lower unit installation bolts, and pull lower unit ass’y. Remove the engine gasket and lower motor cover.
  • Page 13 Remove the upper mount rubber instauration bolts. Remove the lower mount rubber cap and lower mount rubber installation bolts. Remove the ground wire bolt. Tilt down drive shaft housing. Remove the ground wire as shown. Remove the engine base and drive shaft housing.
  • Page 14 Bracket <Assembling> When assemble drive shaft housing parts, reverse the disassembling procedure. Tightening torque as follows: Size x Q'ty 1 st Engine mount bolt 1.9-2.1kg.m Bracket nut 2.4-2.6kg.m Mount rubber(upper) 4.0-5.0kg.m Mount rubber(lower) 3.5-4.5kg.m 2.4-2.6kg.m Gear case mount bolt 3.8-4.2kg.m *Notes Put in the dowel pin and assemble.
  • Page 15 Drain the gear oil. Tilt up the outboard motor. Remove the spring pin of shaft rod joint using spring pin tool (369-72217-0). (Lower unit can be separated without removing of the gearshift shaft) Remove the lower unit installation bolts, and separate the lower unit ass’y from the driveshaft housing.
  • Page 16 When pulling out propeller shaft housing, remove clutch push rod steel ball together with the housing ass’y as shown. Remove the water pump housing, impeller and impeller key. Fix gear case on a vise with propeller shaft housing opening upper makes for easy work. Remove the bevel gear nut using special tools (Bevel gear nut wrench (353-72231-0) and socket (345-72232-0)).
  • Page 17 *About necessity of the backlash measurement management The recent outboard motor tends it to be upsized. The gear in the lower unit transmits the big output to a propeller only by the primary gear reduction of bevel gear. The load to depend on each gear becomes a considerably much bigger. In addition, the gear case is used in the water.
  • Page 18 1. Assemble the drive shaft spring, the guide drive shaft spring, the drive shaft, A gear, B gear, and propeller shaft housing to the case. In this case, attach the same shim. Tighten each bolt and nut as specified torque. (Apply Three bond 1342 to the thread after degreasing.) Size 1 st...
  • Page 19 4. Turn the driveshaft 6 times by pulling the driveshaft to the top side. This means for stable thrust taper roller bearing contact. 5. Attach backlash measuring tool clamp to the driveshaft. 6. Measure the backlash 4 points by each 90 degree. Proper backlash A-B : 0.24-0.48mm Proper backlash B-C :...
  • Page 20 7. Reassembling procedure after your result is within the proper backlash. 8. If your result is out of specification, disassemble again and add or less a shim and assemble and measure the backlash. When you measure the backlash, tighten the nut with specification torque.
  • Page 21 The tooth contact is ideally 60 % of the tooth contact center from out end of the tooth as shown without a load to the gears. This contact will be moved to the outside by 30% on full load condition which is normal movement. Full load No load 10 .Measure backlash of C gear...
  • Page 22 Lower unit <Assembling> When assembling lower unit, reverse the disassembling procedure. Tightening torque as follows: Size 1 st Bevel gear nut 4.0-6.0kg.m 2.4-2.6kg.m Gear case mount bolt 3.8-4.2kg.m *Note (1) Don’t reuse removed shift rod spring pin, replace with new one. (2) When assemble gear case to driveshaft housing, install firstly the bolts as shown B and then install another bolts.
  • Page 23 Removal and installation of needle roller bearing in propeller shaft housing. 1) Removal of needle roller bearing (1) Attach retainer (3B7-72903-0) to shaft groove II. Insert shaft to propeller shaft housing from same way. (2) Install bearing puller guide (3B7-72727-0), bearing puller plate (3B7-72725-0), washer and nut as following picture.
  • Page 24 Removal and installation of needle roller bearing in gear case 1) Removal of needle roller bearing (1) Insert a shaft (3B7-72702-0) to gear case from A direction. Attach retainer (353-72703-0) to grooves IV of the shaft (3B7-72702-0) from propeller shaft side B.
  • Page 25 Removal and installation of taper roller bearing outer race in gear case 2) Remove A gear bearing outer race. (1) Set bearing puller to gear case as picture. Tighten the nut by spanner, and remove the outer race. (Put the craw of puller in the groove in the back of outer race, Hook claw on the outer race to fix it.) 2) Install A gear bearing outer race (1) Fix the gear case on a vice with its propeller shaft opening facing upside as shown.
  • Page 26 <Adjustment before firing> Engine Throttle linkage connection PS pre- setting <Adjustment in running> Check each link adjustment Carburetor synchronizing PS adjustment Idling adjustment Trolling adjustment and check Check WOT (for test propeller) and/or boat running test Standard bolt and nut torque as follows: 0.13-0.18kg.m 0.27-0.36kg.m 0.47-0.64kg.m...
  • Page 27 Standard Inspection data Engine Measurement point Specification(M70C) Piston diameter 12mm from the bottom of piston skart 73.94-73.96mm Piston clearance Clearance between piston and sleeve 0.04-0.08mm Piston ring Top ring clearance 0.22-0.37mm Second ring clearance 0.22-0.37mm Crankshaft Waggle the core within 0.05mm...
  • Page 30 M70C Disassembling & Reassembling procedure 2007 by TOHATSU Corporation, Japan. Edition, Sept 2007 All rights reserved. Any reprinting or unauthorized use is expressly prohibited without the written permission of TOHATSU Corporation, Japan.