Zipped Against Being Zapped

Maintenance Q & A — July 2001
Maintenance Q & A — July 2001
By Capt. Ken Kreisler

Zipped Against Being Zapped
Waterproofing electrical connections, proper operating temperature for a diesel, and more.

 More of this Feature
• Part 1: Waterproofing Electrical Connections
• Part 2: Stop Condensation, Checking MSD Motor

 Related Resources
• Maintenance Q&A Index

I recently discovered that my VHF signal was weak due to water getting into the antenna connector. What's the best way to prevent this? J.S.,via e-mail

Water infiltration is the number-one problem with marine connectors. Moisture will penetrate any unsealed connector, making its way into the fine strands of the center conductor and eventually into the cable itself. The copper strands will react chemically with the water to form copper oxide, which acts as an insulator and provides resistance to any signal trying to cross it. The higher the resistance, the lower the signal strength.

While you can bend a couple of drip loops in the line to catch and divert any water that may run down the cable, the best way to protect your electronic connectors is by also using adhesive-lined, heat-shrink tubing. Using a hair dryer on high or a heat gun, the tubing will shrink up to 85 percent while the adhesive flows and seals the connection.

What are the results of running a diesel engine at cooler than usual operating temperatures? B.V., via e-mail

As per your owner's manual, correct operating temperatures are critical to engine performance. In order for an engine to run efficiently and to prevent failures, it must reach a specific operating temperature and stay within defined limits.

As far as running a diesel in cold operating temperatures is concerned, continued use can result in sludge formation in the crankcase. Sludge can gum up valve lifters and stems, as well as pistons and rings. In addition, if your diesel fuel has a high sulfur content, sulfuric acid can form more readily and hasten internal corrosion. Cold operating temperatures can also lead to carbon buildup on such critical components as valves.

As with all important engine maintenance, preventive care is the solution. Check your owner's manual for the correct operating temperatures and do regular inspections of all hoses, hose clamps, water pumps and seals, zinc pencils, thermostat, coolant type and level, and impeller.

Is there a way to tell if there is water leakage in one or more of the cylinders of an outboard engine? G.R., via e-mail

Checking the spark plugs is the fastest and easiest way since water will clean them. If one is measurably cleaner than the others, there is most likely a water leak in that cylinder.

To be sure, remove all the spark plugs, and if you can find a set of dirty ones, insert them in place of the clean plugs. Run the engine for 10 minutes, shut it down, then examine the plugs to see if one is cleaner than the others. 

Next page > Stop Condensation, Checking Your MSD Motor, and more > Page 1, 2

This article originally appeared in the May 2003 issue of Power & Motoryacht magazine.

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