Operating an outboard motor requires regular maintenance, and for owners of low-power models such as Tohatsu MFS 5CThe ability to self-defeat is becoming a key skill: properly disassembling the unit allows not only to eliminate malfunctions, but also to extend the life of the engine, preventing costly overhauls in the future. Owners often face the need to access internal components due to water intake, problems with the carburetor or wear of the lower unit part.
The dismantling process requires not only the presence of a special tool, but also a clear understanding of the sequence of actions, since the design of two-stroke and four-stroke models has its nuances. Violation of assembly order This can lead to depressurization of the crankcase or damage to the gaskets, which is critical for water engineering, and in this article we will look at the stages of disassembly in detail, paying attention to the specific points of work with Japanese engineering.
Before starting work, you need to prepare a clean, well-lit workplace, where dust and dirt are excluded. It is critically important to remember or photograph the position of the carburetor adjusting screws before twisting them.Because the factory settings are optimal for the fuel mix, any interference with the fuel system without fixing the initial parameters will require re-tuning the finer to the hearing and tachometer.
Workplace preparation and necessary tool
Quality disassembly is impossible without a properly selected set of tools, which must include both standard and specialized elements. Tohatsu 5bhp You will need caps and carob keys of appropriate sizes, a set of screwdrivers (including cross and slit), as well as end heads with extension cords. Particular attention should be paid to the state of the faces of the tool, so as not to break the thread on the bolts, which could be boiling with time and moisture.
To fix parts and work with the fuel system, a special flywheel remover and a dynamometer key are often required, which will ensure the correct tightening moment when assembled back. Dynamometer key is a mandatory element when working with the cylinder head and lower unit nuts, since the pull can lead to deformation of the metal, and the tightness - to loss of tightness.
⚠️ Warning: Before starting any work, be sure to disconnect the fuel hose and make sure there is no gasoline left in the float chamber to eliminate the risk of fire or ignition of vapors.
The organization of the space also plays an important role: prepare containers for sorting the fasteners, as bolts of different lengths can be used in the same-looking holes. Chaotic folding of parts will lead to a loss of time and possible assembly of the unit using the wrong fasteners, which is unacceptable.
☑️ Preparation for disassembly
Dismantling of external components and control system
The first step is always to remove the outer plastic casings (hoods) that protect the internal mechanisms from splashes and mechanical damage. Tohatsu 5 The hood is usually fixed with latches and screws, which must be carefully twisted out without undue effort to avoid breaking the plastic locks. After removing the upper casing, access to the fuel pump, carburetor and ignition system is opened.
Next, disconnect the gas cable and, if the model is equipped with an electric starter system or has sensors, the corresponding electrical connectors. Electrical contacts It is recommended to pre-treat with a spray-cleaner, and when assembled lubricate with dielectric lubricant to prevent oxidation. The throttle control cable requires careful handling, since damage to its shell will lead to the gas handle.
Removal of the ramper and the rotary handle is also performed at this stage, if the design of the motor involves their dismantling for easy access to the mounting units. In some versions, you need to remove the gear lever, pre-fixing its position or remembering the setting.
- 🔧 Carefully click the plastic hood locks so as not to damage the latches.
- ⚡ Disconnect the high-voltage wire from the spark plug before any work in the engine compartment.
- 💧 Pour the oil residues from the crankcase (for four-stroke models) through the drain hole.
After removal of the outer pendant, access to the carburetor and intake manifold is opened, which often require cleaning and inspection. Intake manifold should be inspected for cracks, since the suction of excess air disrupts the engine at idle speeds.
Disassembly of the fuel system and carburetor
Motor fuel system Tohatsu 5bhp It's very reliable, but it requires periodic cleaning of the jelly and float chamber from dirt and tar deposits. To remove the carburetor, you need to disconnect the throttle and the fuel hoses, before cutting off the fuel supply. It's important to take care of small parts, such as springs and needle valves, that can fall out when you're not handling it properly.
Inside the carburetor are jelly-clears of various calibers, responsible for the operation of the engine in different modes. Blowing out the jelly Compressed air and washing with a special carburetor cleaner is standard maintenance procedure. If the engine has been out of work for a long time, rubber seals can sulphur, and they are recommended to be replaced with new remixes.
Nuances of Tohatsu carburetor settings
The factory setting of the carburetor is usually to turn the screw quality mixture by 1-1.5 revolution. However, the exact value depends on the altitude above sea level and air temperature.
When resetting the carburetor, it is critically important to correctly place the gaskets between the carburetor and the intake manifold, and between the manifold and the cylinder block. gasket will lead to air sucking, impoverishment of the mixture and overheating of the piston group.
Removal of the flywheel and diagnosis of the ignition system
Access to the ignition coil and the CDI sensors is only open after the flywheel is dismantled, which is one of the most difficult stages of disassembly. Tohatsu You have to use a special skipper because you try to knock it down with a hammer, you have to destroy the crankshaft or the flywheel itself, and the carvings on the shaft are usually right, but you have to stop the crankshaft before you unscrew the flywheel.
Under the flywheel are the ignition coil, the crankshaft position sensor (Hall sensor) and the starter coil (if any). The gap between the coil and the flywheel magnets It must be strictly regulated and usually 0.3-0.4 mm, the adjustment is carried out with the help of a probe.
Visual inspection of flywheel magnets is also mandatory: they should not be chipped, cracked or traces of overheating. If the magnets have lost their properties or are damaged, the flywheel should be replaced, since it is impossible to restore the magnetic field at home.
⚠️ Attention: When installing the flywheel back, make sure that the veneer (pin) is installed in the groove perfectly smoothly. skewed or crumpled veneer will cause the ignition angle to shift and possible engine destruction.
Use a marker to make marks on the flywheel and hub before removing, if visual control of the veneer is difficult - this will help make sure that the landing is correct during assembly.
Disassembly of lower unit and Reductor
The bottom of the motor, or lower unit, contains a gearbox, a gearshift system, and a propeller shaft. To remove the lower unit, you need to twist the bolts to the cylinder block and carefully disconnect the gearshift thrust and engine shaft from the clutch. The gearshift traction requires careful attention, since its bending or improper adjustment will make it impossible to turn on neutral gear or front/revers.
Inside the gearbox are gears of the front and rear, as well as bearings lubricated with a special transmission oil. Consistent lubrication Bearings and the presence of oil in the body of the gearbox are key factors in the durability of the unit. When disassembling, you should check the condition of the coils, through which water often enters the gearbox.
The propeller is removed first, but inspection of its blades and anti-cavitation plate is carried out when the lower unit is disassembled, the presence of bullies on the propeller or the beating of the shaft indicates problems with bearings or collision with underwater obstacles.
When assembling lower unit, special attention is paid to the moment of tightening of the mounting bolts and the quality of the gasket installation between the lower unit and the cylinder block. gasket It must be new, as reuse of the old one can result in exhaust gases entering the cooling system or water entering the crankcase.
Defection of the piston group and cylinder block
Disassembly of the top of the engine, including removal of the cylinder head and removal of the piston, is required when compression loss, knocking or increased fuel consumption. Removal of the block head is carried out after unscrewing the bolts in a specific sequence (usually cross-cross) to avoid distortion. Block head is checked for cracks, especially in the saddle area of valves (for four-stroke) or purge channels (for two-stroke).
The piston is removed after the piston finger lock rings are removed. The piston mirror should not have deep bullies, and the rings should be elastic and not be enclosed. The gap between the piston rings and the grooves is checked with a probe, and if it exceeds the permissible limits, the piston group is required to be replaced.
For four-stroke models Tohatsu MFS 5C Also important is the inspection of the valve mechanism: the gaps of the valves must be adjusted according to the specification. heat-gap affects the power, stability of idling and can lead to burnout of the valves.
| Parameter | Normative value | Permissible wear and tear | Unit of measurement |
|---|---|---|---|
| Compression | 9.0 - 11.0 | Minutes 7.5. | kg/cm2 |
| Valve clearance (intake) | 0.13 - 0.17 | - | mm |
| Valve gap (release) | 0.18 - 0.22 | - | mm |
| Oil in the gearbox | 130 - 150 | - | millimeter |
Regular check of compression and condition of spark plug allows to identify problems with piston group at an early stage, before expensive repairs.
Motor assembly and initial start
Engine assembly Tohatsu 5 It is done in reverse disassembly, but with strict rules for tightening threaded joints. All gaskets, glands and sealing rings removed during dismantling should be replaced with new ones from the remix. The use of old seals is unacceptable, because they lose elasticity and cannot ensure tightness.
Before installing piston rings and piston in the cylinder, you need to grease the parts with engine oil abundantly. When inserting a piston into the cylinder, you need to monitor the correct location of the ring locks and carefully guide them so as not to damage the chromium coating of the cylinder. Puff moment The bolts of the block head and the lower unit should be controlled by a dynamometer key according to the table of moments for a particular model.
After full assembly, you need to check the free running of all cables, the level of oil in the gearbox and crankcase (for 4T), as well as the availability of fuel in the system. The initial start is better done on a stand with a water tank or in water, monitoring the operation of the cooling system and the absence of extraneous noise.
- 🛢️ Pour fresh oil into the gearbox before the oil appears in the upper control hole.
- 🔩 Check the tightening of all mounting bolts after the first warm-up of the engine (pull).
- 🌊 Make sure that a confident stream of water comes from the control hole of the cooling system.
⚠️ Warning: Do not start the motor without water supply to the water pump even for a short time - this is guaranteed to disable the impeller pump and can cause the unit to overheat.
Post-repair break-in
If you have a piston group replacement or gearbox repair, the engine needs to run. For four-stroke Tohatsu, this is usually 10 hours of operation in a gentle mode (no more than 50-60% of power), with periodic oil change after the first 20 hours of motorized operation.
Frequently Asked Questions (FAQ)
How often should I change the oil in the Tohatsu 5 gearbox?
The oil in the gearbox is recommended to be changed once a season or every 100 motor hours. At the first maintenance of the new engine (after the first 20 hours), replacement is required to remove the products of the gears running.
Can I use car spark plugs?
No, you can only use candles recommended by the manufacturer (usually NGK of certain kalyl numbers). car candles have a different kalyl number and thread, which will lead to kalyl ignition or damage to the thread in the head.
Why is the Tohatsu 5 engine not idling?
The most likely causes: air suction through the carburettor gaskets, idle jellier contamination or improper adjustment of the screw quality of the mixture, it is also worth checking the condition of the fuel filter-sludge.
Do I need to grease lower unit before storage?
Yes, before long storage (winter), it is recommended to lubricate the lower unit slits and the propeller shaft with a special lubricant to prevent stiffening and corrosion.