Operating the outboard motor in fresh or salt water requires constant monitoring of the cooling system. pump Rubber has the ability to lose elevity, crack or wear over time, which inevitably leads to overheating of the engine. If you notice a decrease in the pressure of water from the control hole or an increase in the operating temperature, you can not delay.
Timely replacement of impellers is a way to prevent costly powertrain repairs, a procedure that requires care, but is feasible in garages with a basic set of tools. In this article, we will discuss in detail the process of dismantling the gearbox, removing the old pump and installing the new remix using two-stroke and four-stroke medium-power engines.
The main rule before work is to ensure cleanliness and order. Getting dirt, sand or old sealant inside the lower unit can lead to jamming gears or damage to the osteoils. So prepare a clean rag, oil tank and a workplace with good lighting. Don't ignore the need to replace the osteoils, as their resource often coincides with the resource of the impeller.
Tools and preparation for work required
Before we start the demolition lower unit The lack of the right key at a critical moment can cause bolt edges to break or thread damage. Tohatsu, Yamaha or SuzukiYou will need a standard set of heads and screwdrivers.
Pay special attention to the condition of the tools. Dirty or oil keys can slip, damaging the aluminum body of the lower unit, which can violate the tightness. Also, purchase a water pump kit in advance, which usually includes the impeller itself, the bottom and top plates, and sealing rings.
You will need the following tools and materials:
- 🔧 Set of heads with a rattle (including an extension cord)
- 🪛 Set of cross and flat screwdrivers
- 🔨 Hammer (preferably with a lump of non-ferrous metal or plastic)
- 🧴 Heat-resistant water-resistant lubricant (e.g., lithium-based)
- 🧼 Degreasing and clean rags
⚠️ Attention: Before starting work, be sure to remove the motor from the transom or securely fix it on the rack. Working under the weight of the suspended motor is dangerous and can lead to injuries.
It is also important to prepare the container for the used transmission oil. Although we do not always drain the oil from the gearbox completely when replacing the pump, the risk of water contamination or getting inside during dismantling is high, it is better to plan the change of oil in the gearbox immediately after all work is completed.
Demolition of DW and access to the pump
The replacement process starts with removing the bottom of the motor, and you have to disconnect the gearshift traction and free the lower unit from the locking bolts. On different motor models, the mounting bolts may be different, but the principle remains the same. First, remove the plastic casing that closes the connection of the lower unit to the lower unit pipe.
Disconnecting the gearshift traction requires care, usually with a splint and a finger or a special clamp, and once the locking member is removed, the thrust must be carefully removed from the engagement, and if the thrust is not removed, you may need to turn the shaft to fit the holes.
Next, you unscrew the bolts that connect the lower unit to the main part of the motor, which range from 4 to 6 pieces depending on the power. Bolts can be of different lengths, so it is recommended to lay them out in the order in which they were twisted, or use a circuit, which will prevent errors in the assembly.
☑️ Preparations for the removal of lower unit
Once all the bolts are removed, lower unit should be gently lowered down, at which point the water intake shaft will disconnect (in some models it sits tight and requires careful swaying), make sure that the shaft does not fall or get lost, and now you have access to the water pump assembly located above lower unit.
Disassembly of the water pump assembly
The pump assembly is usually attached to the lower unit tube with several bolts, and when you unscrew it, you remove the metal base plate, followed by the pump body, and inside you see a rubber impeller, which is worn on the slate part of the shaft, and often the impeller sticks or deforms, repeating the curves of the body.
It can take a lot of effort to remove the impeller. Use two screwdrivers, carefully fitting the blades, or a special detacher if you have one, the main thing is not to damage the shaft and the slags. After removing the impeller, remove the lower and upper plates, as well as the O-ring. Carefully clean the landing place of residue old lubrication, corrosion and dirt.
Check the shaft for development or damage. If there are deep furrows from the osteoils on the shaft, simply replacing the impeller may not solve the air sucking problem. In such cases, deeper repairs or replacement of the shaft are required. Also check the condition of the water intake tube that runs inside the lower unit.
Nuances of pump design
In some engines, such as older Mercury or Johnson models, the pump design may include additional washers or have a specific plate assembly sequence. Always check the manual for a particular model, as the direction of rotation of the impeller may differ.
The cleaning should be perfect. Any grain of sand left inside the casing will become an abrasive for the new impeller and reduce its lifespan by many times. Use a degreaser and compressed air to finalize the ducts. Make sure the holes in the metal plate are not clogged with sediments.
Installation of new impeller and assembly
The assembly starts with a new impeller. The key here is the direction of rotation. Most outboard motors have an impeller that swirls clockwise (when viewed from above), but there are exceptions. Before installation, grease the inner surface of the impeller and blades with waterproof lubrication.
Lubrication has two functions: it provides initial lubrication when starting the engine until the water is in, and it facilitates the installation of the impeller in the body. Carefully insert the impeller into the body, holding the blades with your fingers or using a clamping blade. The shovels must be directed towards the rotation, so that the first start they straighten correctly.
Then you put the plates in. You put the bottom plate first, then the impeller, then the top plate. It's important not to confuse the sides of the plates if they have different configurations of holes. Once the plates are installed, the assembly is assembled into a single block and put on a shaft. When you lower the datawoot, you need to control that the water intake shaft gets into your nest.
⚠️ Attention: When you lower the daydvut, watch the crankshaft coil. The shaft should enter smoothly, without distortion. If Daydwood is resting and does not go, do not use force - lift it and check the position of the shaft and the glands.
The final assembly step is to tighten the die-woot mount bolts, use the dynamometer key if possible to observe the manufacturer's specified tightening moment, and the tightening can cause the aluminum flanges to deform and leak, and the tightening can cause vibrations and loss of the node on the water.
Table of tucking moments and specifications
To ensure reliable connection, it is important to follow the manufacturer's specifications, below are indicative data for popular brands' engines, but always prioritize information from the service manual of your particular model.
| Parameter | Tohatsu / Nissan | Yamaha | Suzuki |
|---|---|---|---|
| Daydwoot (Nm) fastening bolts | 28 - 35 | 30 - 38 | 25 - 32 |
| Pump bolts (Nm) | 4 - 6 | 5 - 7 | 4 - 5 |
| Type of pump lubrication | lithium | Waterproof | molybdenum/Lithium |
| Replacement interval (hours) | 300 or 1 year | 300 or 1 year | 300 or 1 year |
Compliance with puff moments is particularly critical for pump bolts. The aluminum case is easily damaged by excessive force. If the thread is broken, it will be extremely difficult to restore it in the field, which may require replacing the entire lower unit pipe.
System inspection and first start-up
Once the engine is assembled, you need to check the tightness and performance of the cooling system, start the engine on a barrel of water or connect the forced water supply system ("soul"), immediately after starting, a stream of water should go out of the control hole, and its absence indicates a problem.
If the water is not running, turn off the engine immediately. Working without cooling for even 30-60 seconds can cause critical overheating of the piston group. The reasons for lack of water can be as follows: improperly assembled pump, clogged feed channel, air traffic jam or inverted impeller.
Let the engine run at idle speeds for a few minutes. Check the datawoot connection for water or oil leakage. Make sure the gear thrust is working correctly and the gear switching mechanism is running smoothly.
When you first start after replacing the pump, let the engine work for 2-3 minutes on idles, then briefly add gas. This will help the impeller to spread and get into place, and also drive out possible air traffic jams.
Frequent mistakes and helpful tips
One common mistake is to use the wrong lubricant. Conventional solidol or graphite lubricant can dissolve in water or cause rubber to swell. Use only specialized water pump lubricants that are labeled as water pump grease.
Also often forgotten is to replace the sealing ring between the lower unit and the lower unit pipe. The old ring can lose elasticity and let water into the lower unit, which will lead to emulsification of the transmission oil. Always change the seals every time you disassemble the knot.
Another important aspect is the direction of rotation. If you mix the sides of the plates or install the impeller incorrectly, the pump will not pump water, but only warm up. Before the final tightening of the bolts, check visually the installation conforms to the circuit.
The quality of rubber impellers depends on the storage conditions. Do not buy hand-held remixes or those in warehouses without packaging, as rubber tans over time even without use.
Don't ignore the condition of the veneer on the shaft. If it has any traces of crumpling or production, it needs to be replaced. The weakened veneer will cause the impeller to roll into the shaft, which will instantly stop the water circulation and cause overheating.
How often should I change my squirrel?
Manufacturers recommend changing the impeller once a year or every 300 hours, but in conditions of operation in muddy, sandy water or frequent parking in shallow waters, it is better to reduce the interval to one season.
Can I grease the stain with ordinary oil?
It's not recommended. Regular motor oil will quickly wash away with water on the first run, and dry friction will destroy the new impeller in seconds. Use only thick water-resistant lubrication.
What if there is no water pressure after replacement?
Check if the impeller is inverted, if the plates are intact, if the control channel is clogged, and also make sure that the water level in the container is sufficient for pumping.
Should I change the lower unit oil when replacing the pump?
Preferably, because the lower unit is still being removed, replacing the glands will prevent water from entering the gearbox in the future, which is inexpensive and greatly improves the reliability of the unit.
Replacing your impeller is a simple but important operation, and by doing it regularly and efficiently, you can extend the life of your outboard motor and ensure water safety. Don't skimp on refits and lubrication, because the cost of these parts is not commensurate with the risk of major engine repairs.