How To Avoid Aluminum Corrosion in Boat Engines
August 1, 2009 by Chris Wethered
Filed under Boat Engines And Sailboat Hardware, Questions Visitors Are Asking And Answers
Boat engines, both inboard and outboards use aluminum for a range of reasons. Here a few that come to mind:
- Outdrive casings
- Protective tubing or piping
- Radiators / heat exchange – DIY projects
- Holding tanks
There are other uses for the alloy, but they all share the same problem – Salt water erosion.
Basically any metal when put in salt water erodes, the rate of erosion depends on how reactive that metal, or alloy is – remember your chemistry experiments!
Electrolysis occurs and there is a flow of direct current created. The more metals in the salt water the quicker the erosion. The solution lies in prevention rather than cure. Cure can be very expense and prevention not so.
Does your lower unit look this?
Regularly checks
To avoid corrosion, you must regularly check your aluminum components. Some advice says weekly, some say monthly. It’s up to you. It’s best to monitor more often than not, until you have an idea of the rate of attrition.
So start frequently and then lengthen your checks. The individual environment of your components dictates the corrosive nature of salt water.
Outboard checks
- All wires, particularly the junction box. Which serves two functions. First the charging system of the engine, second to power the electrical choke. Look out for green erosion and loose wires
- The cylinder gasket head. Get under the hood. If the head is weakened and water gets in then you will suffer a hydraulic lock. This can easily be avoided. Depending on the make of your outboard you may need to have the sacrificial anode replaced when the gasket is decarbonized by your local shop.
- Replacing sacrificial anodes. Whether zinc or aluminum alloy, these should be replaced when one third of the original anode has disappeared. Never use two different metals for your
anodes. You must get your outdrive casing and your anodes electrically bonded. This balances the charge between the two metals. Otherwise the corrosion that follow will cause damage very quickly to your lower unit. That’s the reason not to use different metals as anodes too.
These bolts are subject to galvanic erosion
Inboard checks
- Replace your anodes as described above. You can use an ohmmeter to determine the charge differential between your metals, for the electrical bonding.
- Use corrosion inhibitors. They are designed to protect and extend the life of boat engine components. Counteracting the aggressive nature of salt water erosion.
- Tightening up loose wires, bolts and screws. Due to the vibration of the engine
Long or short term cure?
The trick with inhibitors is this; if your looking to seal and protect your metal work for an extended period of time then use a thicker one. Conversely, if you check back more often then use a lighter one. The leading products on the market are galvanic isolators. When your hooked up to shore power, they maintain AC current. Which prevents zinc damage.
What is the West Marine sale all about? 10% discount off orders over $100!
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How to grease two stroke engines
Fixing the outboard engine to the transom
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How To Grease A Two Stroke Engine?
July 27, 2009 by Chris Wethered
Filed under Boat Engines And Sailboat Hardware, Questions Visitors Are Asking And Answers
Visitors have been searching for the answer to this question
So here's an overview diagram:
Diagram showing where to grease 2 stroke engine
Follow the manufacturer's guidance on frequency and quantities
You should check out the manual that came with your engine. The specific lubrication points vary from one to the next.
Getting the grease balance right is straight forward, but on the whole to much is better than too little.
How often you grease depends on the useage of your outboard. It's best to check more often than not, until you have a routine going.
Finally to grease those difficult to reach points get a grease gun, with a needle point adapter. These deliver grease accurately and with minimum wastage or clean up!
Getting the oil / gas mix right
- Remember to put the oil in the tank first - then the gas.
- Follow your manufacturer's guidelines on the ratio!
- Most will specify which grade to use and the ratio involved.
- If your engine has variable ratio oiling then all this is taken care for you!
Take advantage! West Marine are offering a 10% discount, when you spend over $100!
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Outboard engines and transoms info
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