Any experienced boater knows that even a slight vibration on the transom can ruin the most pleasant journey. propeller-sleeveIt stops effectively quenching the vibrations and transferring torque from the engine to the blades, and ignoring this symptom can lead to serious consequences, including damage to the lower unit or the gearbox itself.
In this article, we will go into detail about the design of the unit, the symptoms of malfunction and the process of self-replacement of the element. You do not need to be a professional mechanic to perform this procedure in the garage or on the shore with a basic set of tools. Proper maintenance of this part is the key to quiet operation of the engine and fuel economy.
Diagnosis of faults of the rowing unit
The first sign that rubber-sleeve The exhaustion of the energy is the appearance of a knock or vibration when the engine is running at idle speeds. When you add gas, the vibration can temporarily disappear, because under the load, the parts are pressed tighter, but when the gas is discharged, the noise returns. This is a classic symptom of the screw slipping relative to the hub.
In some cases, visual inspection may not yield results without dismantling, so it is worth paying attention to the behavior of the boat on the water. engine speed They're growing, and the speed of the boat is not increasing, so it's slipping, and it's also alarming that there's a metal shaving in the gearbox oil, which indicates that the metal parts are frictional because the screw is shifting.
⚠️ Warning: Operation of the engine with a broken bushing can lead to a rotor turning at high speeds, which is fraught with loss of control of the boat at a critical moment.
Accurate diagnosis sometimes requires removing the screw and checking for backlash. If you're swaying the screw with your hand, you feel free to move relative to the shaft, or if you see signs of a snag on the inside of the hub, repair is inevitable. Most modern motors use a system. Splined Rubber HubIt does not require adjustment but needs periodic replacement.
Required tools and materials
Before you start, you need to prepare the workplace and tools. You need a sturdy stand or a wooden bar to spin the screw when you unscrew the nut. Without a reliable fixation, it will be extremely difficult to break the time-stretched nut, and the risk of damaging the blades to the ground is very high.
The basic toolkit includes the appropriate size end heads, the collars and possibly the impact screw if the nut is boiling. lubricant For lower unit shafts that are resistant to leaching and corrosion in salt water, the regular lithole is not suitable here, because it will quickly lose its properties.
To press a new sleeve in some cases, you may need a hydraulic press or special mandrels, but for most amateur motors, careful work with a hammer and wooden flooring is enough. It is important to have a contact cleaner or acetone on hand to degrease surfaces before assembly.
☑️ Preparation for repairs
Dismantling of propeller
The process of removing the screw starts with safety. Be sure to shut off the engine and remove the candle wires to prevent accidental start. If the motor has a start lock system, make sure that the key fob is in your pocket and not hanging on the engine.
Then you need to unscrew the screw attachment nut, use pliers or bogocreas to remove the locking splint, and if the splint is rusted and doesn't respond, you can carefully drill it or snack on it with cutters, trying not to damage the shaft thread.
Once the splint is removed, unscrew the nut. It's important not to lose the thrust washer, which is often removed along with the nut. Remove the screw from the shaft, supporting it with both hands, as it has considerable weight. Be careful with the sharp edges of the blades, they can be even without visible damage.
| Motor type | Shaft diameter | Type of fixation | Nuances withdrawals |
|---|---|---|---|
| Tohatsu / Nissan | Standard | Splint + Nut | WD-40 is often required |
| Yamaha | Standard | Splint + Nut | Careful with the pucks |
| Mercury | Standard | Splint + Nut | Difficult access to splint |
| Suzuki | Standard | Splint + Nut | It takes 50-60 Nm to do it. |
What to do if the screw is not removed?
If the screw is stuck to the shaft, don't try to knock it down with blows to the blades. Pour the connection with a penetrating lubricant (for example, WD-40) and leave it for 15-20 minutes. You can also try to carefully warm the hub with a construction hairdryer, avoiding heat on the coils of the gearbox. In extreme cases, special detachers are used that rest on the gearbox body and press the screw shaft.
Analysis of the condition of the old sleeve
After dismantling, carefully examine the inner surface of the screw hub, if you see that the rubber layer is rolled relative to the metal sleeve or has deep cracks, the part needs to be replaced. Sometimes the rubber can be intact but displaced, which also disrupts the balancing.
Notice the condition of the metal sleeve pressed into the rubber, so it doesn't have to be bullyed, corrosive or shaft-shaft-shaft-shaft-shafted, and if the metal part is damaged, simply replacing the rubber won't help, you'll need the entire hub or screw assembled. Corrosion between metal and rubber is a frequent enemy of knots operated in salt water.
In some designs of screws the system is used Flo-Torq Or similar ones, where you have multiple rubber discs, and they wear things differently, because they can be flattened or they can have gaps at the ends, and they need to be very careful when they're assembled to avoid confusing the order of the disks and the washers.
⚠️ Warning: Never reuse an old sleeve, even if it looks normal. The rubber loses elasticity over time and will not be able to provide the necessary cushioning.
Technology of sleeve replacement
The most difficult part is to press the old one and press the new sleeve, and in the home, this is often done using the knocking method, and the old sleeve is carefully knocked out with a sleeve matched in diameter, striking a circle so as not to skew the metal clip, and you need to act without fanaticism, so as not to deform the screw hub itself.
The new sleeve before installation is recommended to lubricate with soap solution or special lubricant, so that it can more easily enter the hole, pressing is done with the help of a vise, a jack with a spacing or neat blows of a hammer through a wooden prefix. The main effort should be on the metal ends of the sleeve, not on the rubber part.
It's critical to ensure that the sleeve is aligned when pressed, and if the sleeve is skewed, the screw will beat, which will quickly destroy the new part and damage the glands, and after installation, check if the sleeve is protruding on both sides the same way as it was in the factory.
Use a vise and two large washers or heads of the right diameter to press the bushing evenly. This is much safer and more accurate than working with a hammer, and minimizes the risk of damage to the new rubber part.
Assembly of the unit and check of operability
Before installing the screw back, clean the lower unit shaft of old lubricant, algae and corrosion products. Apply a new layer waterproof It's going to be easy to remove the screw in the future and it's going to be very protective against sourcing.
Set the screw on the shaft in order of the washers (if designed). Tighten the nut to the manufacturer's recommended moment. For most outboard motors, this parameter is in the range of 40 to 60 Nm, but the exact data is best found in the manual for a particular model. boat-engine.
Lock the nut with a new screw. If the holes in the shaft and the nut do not match, turn the nut to the nearest match, but never loosen the already tightened nut to hit the hole. After assembly, start the engine on the shore (in the barrel or on the cooling system) and check for no vibration at idle speeds.
Frequent errors in repairs
One common mistake is to use the wrong lubricant: Graphite lubricants or solidol can break the rubber structure or wash out after the first watering. Always use specialized formulations designed for underwater applications.
Another mistake is ignoring the state of the washers and splints. A rusty splint can break inside the hole, and a deformed washer will not transmit the puff force correctly. Using conventional steel splint instead of copper or brass can lead to rapid corrosion and jamming of the knot.
Also, beginners often pull the nut, believing that "the porridge can not spoil the oil." Excessive force can lead to deformation of the shaft thread or the destruction of the rubber sleeve during installation.
⚠️ Warning: After the first exit, be sure to repeat the visual inspection of the node. Make sure that the splint is in place and the nut does not turn under load.
A quality replacement of the sleeve returns the boat to the factory smoothness of the course and prevents expensive repairs of the lower unit in the future.
How often should I change the sleeve of the screw?
The life of the sleeve depends on the operating conditions: in fresh water it can last 3-5 years, in salt water - 1-2 years, but it should be changed not by the time, but by the state: when backlash, knocking or visible rubber damage appears.
Can I drive with a broken bush?
In addition to the discomfort of vibration, this leads to uneven wear of the shaft and hub slits, and can damage the gearbox thrust bearing, and in the worst case, the screw can turn at full speed.
What is the difference between a sleeve and a hub?
The hub is a rubber metal element that dampens the vibrations. The hub is the central part of the screw that the sleeve is pressed into. Most of the time, only the sleeve changes, but if the metal of the hub is damaged, the whole screw needs to be replaced.
Do I need to lubricate the rubber sleeve inside?
The lubricant is applied to the shaft and the inner metal clip of the sleeve to prevent corrosion and snacking, the rubber itself is not necessary to smear abundantly, the main thing is to protect the metallic interface surfaces.