Sterndrive Engine Parts

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Boating Know How
How to maintain the health of my sterndrive

Maintaining the Health of My Sterndrive – 10 Critical Areas

The Sterndrive is among the most popular types of outdrives. Popular brands include the Mercruiser, OMC, and Yamaha mainly found in the US while in Europe the Volvo Penta is most common. These drives are known to be quite ... read more powerful and effective. However, repairing a damaged unit or buying a Sterndrive can be costly.

As a boat owner, you need to pay close attention to the following areas:

1. Fouling

Fouling is always one of the biggest headaches to boat owners. Regular contact with water, especially ocean  water, will lead to marine growth such as barnacles. Getting rid of barnacles usually requires sanding down the area. The application of anti-fouling paint should be done while the engine is still new thus impeding the growth.

2. Electrolysis

Sterndrives are made from metals such as aluminum, steel, iron and zinc. Zinc being anodic (low electrical potential) and aluminum being cathodic (high electrical potential) allows electric ions to flow from the zinc to aluminum. Overtime, the zinc coating will get eroded thus weakening the part. It is, therefore, necessary to maintain the zinc plates and ensure they are cleaned regularly.

3. Corrosion

In certain instances, a whitish powder will coat some parts of the engine. This occurs when electroplating is taking place due to current flow between the metals e.g. from zinc to aluminum. This will only be noticed in dry and not wet conditions. If not corrected in time, the drive will be damaged beyond repair.

4. Lubrication

Like any other outdrive, a Sterndrive will work optimally when there is minimal friction. This is achieved by ensuring the moving parts are moving freely. Visible parts should be cleaned, properly dried and some marine-grade lube or grease applied. The gear oil or lube should also be replaced within the recommended period.


5. Adding Protection

The drives usually come with minimal or no protection. This makes them prone to electrolysis, corrosion, as well as chipping away. There are special compounds that should be used to protect the drive better. These include a pre-primer that removes any corrosion on aluminum. Anti-rust paints are also available for steel.

6. Replacement Parts

Many boat owners will carry out the necessary repairs and service on their Sterndrive. Unfortunately, most will complain of poor performance due to the lack of durability. Usually, the main reason is due to using low a quality Sterndrive engine parts. You should never sacrifice quality for economy as this is always costly in the long run.

7. Drive Shafts

It is important to make sure the drive shaft is moving freely. A bent shaft, a corroded one or a broken seal may make the shafts rotate poorly. This not only consumes power but also harms the engine. Visually inspecting the shafts and seals ought to be done frequently.

8. Chipped Paint

Paint on the drive will wear out or chip over time. This may be caused by poor handling, reckless operation or extended use. Once the bare metal becomes exposed it is necessary to correct it immediately. Proper sanding, applying a primer that resists rust, using quality paint, and following the right procedure are needed.

9. Hoses

The drives feature two bellow hoses; one is for the shift controls and the other for the drive shafts. The water seal between the lower unit and the boat wear out due to use. This may allow water to get in. Things to look into include cracks, rigidness or signs of moisture.

10. Paint Maintenance

Usually, people raise their drives when not in use. Unfortunately, marine paints react with oxygen in the atmosphere. This will affect the anti-fouling properties which ensure corrosion or rust doesn’t take place. Therefore, it is essential to keep the drive submerged in water at all times. Nonetheless, taking it out of water for a day or two won’t cause any harm.

Anyone who’s ever had to repair or replace a damaged Sterndrive understands the high cost of doing so. A single propeller drive will set you back by at least $2500 while a twin-engine will cost no less than $5,000. In fact, buying a new drive unit may cost more than half the price of what the boat is worth. Regularly servicing the engine using proper Sterndrive engine parts will go a long way in avoiding the costly scenarios.
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Prevent Overheating Sterndrive Boat Engines

How to Detect Overheating Sterndrive Engines

Boat engines require regular maintenance and upkeep to maintain longevity and health throughout the years. Specifically, sterndrive engines face the constant threat of ... read more the cooling system deteriorating, causing the engine to overheat and cause potentially serious damage to the entire vessel. Checking on the cooling system on a regular basis is fundamental and highly recommended. Doing so will prolong the life of your sterndrive and enjoyment on the water.

Signs of Over Heating

There are a few key concepts to the cooling system that you will want to check immediately if you notice that the temperature gauge is gradually or rapidly rising. The components in the water pump will be the first thing to examine. The impeller is one of the more likely engine parts to be susceptible to decay, which, by extension, leaves the engine more vulnerable. Impellers are one of the only cooling engine parts that can be completely ruined at both low and high speeds, so be especially aware of the state of your impeller. Replacing the impeller may happen more often than replacing any other cooling component. Other cooling parts that you will want to keep an eye on include hoses, manifolds, thermostats, and so on.

There are scenarios that you must either try to steer clear of or take immediate action should they occur. Some of these situations include: Sterndrive
  • Sand getting sucked into your engine
  • The boat sitting out for a year or more without turning on the ignition
  • Low or no water supply in the engine (if this goes unchecked, the impeller will be destroyed in less than one minute)

Furthermore, most technicians/mechanics will recommend that you replace or at least repair your water pump at least once a year. There are a few things that will indicate that your water pump needs to be repaired or replaced. As previously mentioned, you will be able to tell that there is something wrong with the impeller if the temperature spikes rapidly at low or high speeds. Other “symptoms” may appear under the following circumstances:
  • At higher speeds, if the temperature is slowly climbing upwards, this may indicate that the exhaust manifolds or rise water passages are wearing or are worn down.
  • If you turn on the ignition and leave it sitting idly in the water or at the dock and the temperature starts to gradually creep up, this may mean that the thermostat is faulty.

If you diligently examine your engine and maintain and repair your water pump on a regular basis, your engine will last longer and prevent expensive occurrences. Keep your boat engine running smoothly and be mindful of these signs.

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Rotating Electric Marine Starters (Video)
A video presentation on rotating electric marine starters by SeaStar Solutions ... read more

Video Transcript

Sierra’s new replacements starters meet or exceed OEM output specifications for guaranteed performance. A high temperature epoxy armature provides strength to secure and insulate wires. Permanent magnet units are designed for more torque and longer life. In 19/10 copper bushings our heavy-duty needle bearings provide longer service. Marine starters and alternators must be ignition protected to reduce the possibility of explosion onboard. They must be sealed to prevent water intrusion and corrosion and tested for Coast Guard compliance.

All Sierra starters and alternators are designed exclusively for marine applications and meet UL standards for Stern drive and inboard applications. They also comply with international CE standards required by the European Economic Community. The units are tested and include printed test results to ensure out-of-the-box performance.

Sierra starters cover a wide range of applications. Nothing takes more abuse than a Marine starter unless of course it is a Marine diesel starter. Working in a harsh environment and starting a high compression diesel engine time and time again, the diesel starter needs to be built rugged to continually perform. That is why all of the Sierra diesel starters are engineered and built to exact specifications to perform as good as if not better than OEM components they are replacing.

Like all Sierra products, our electric rotating components are backed by our industry leading warranty. Rotating electric components are exposed to a demanding environment. Sierra’s limited warranty gives you unparalleled pace of mind protecting both you and the customer in the case of part failure. The Sierra warranty pays all associated fees including boat towing fees, parts replacement, incidental parts damage and posted shop labor rates. So no one protects you and your reputation like Sierra. Thanks for watching.
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