4 Important Reasons for Stern Drive Service

Stern drives may not be as popular on the water as they once were, but there are still thousands of them in use across the United States today. If your boat has a stern drive, then you'll want to add transom & stern drive service to your service checklist for the fall. The transom and drive are often neglected as a routine service checkpoint, but their upkeep is crucial to the performance and durability of your boat. Here are the four most important reasons to make sure you are thoroughly inspecting and servicing the transom and drive sections of your boat at least once a year (if not more).

1. Protect the bellows

The bellows are the rubber accordian-style components connecting the transom assembly to the stern drive. There is usually an exhaust bellows through which exhaust is funneled from the engine, and the u-joint or "drive" bellows, which protects the u-joint assembly connecting the mechanical components of the engine and the stern drive. Depending on the brand and model of engine, there can also be a smaller shift cable bellows which protects the shift cables which connect to the stern drive from the engine controls.

Because they are made of rubber, the bellows are especially susceptible to the harsh elements of the marine environment. The sun and heat can harden the rubber over time, making it brittle and easy to crack. Marine growth like barnacles or broken shells can also take hold on bellows, and their razor sharp exterior can cut into the rubber easily. Whenever cracks form, the risk of water leaking into the boat increases significantly. All bellows should be inspected thoroughly for cracks and damage regularly, and they should be kept clean and free of marine growth.

One easy way to get everything you need for proper bellows repair is to purchase a transom service kit. These kits typically contain all the bellows, gaskets, seals, water tubes and the gimbal bearing to do a complete transom overhaul.

2. Prevent corrosion

Since the lower half of the stern drive spends most of its time in the water, it is exposed to the effects of electrolysis. Sacrificial anodes (aluminum or zinc in saltwater, magnesium in fresh water) are attached to the transom and the gear case to attract the electrolysis and protect the stern drive itself. It is important that the sacrificial anodes are inspected and replaced regularly. If anodes are not replaced, corrosion will spread to the propeller and gear case, and the cost of repair will be much higher.

3. Inspect the propeller

The propeller takes a lot of abuse. Aside from the aforementioned corrosion risk, it also is the most likely part to endure collision underwater. It runs into all sorts of rocks and debris, and over time, the shape and strength of the propeller can be compromised. If you are observing a decline in the performance of the boat, it's possible that the propeller needs to be replaced. Check the propeller regularly to ensure it is in good condition. If not, get it repaired or replace it!

4. Lubricate the internal components

Inside the stern drive is a complex collection of gears and bearings all working together to help propel your vessel through the water. In order for those components to work together smoothly, they must be properly lubricated. If the gear lube in the drive is old, its lubricating ability is diminished and it will not properly protect the internal components. Without proper lubrication, the drive can suffer critical damage. Check ALL your fluids every time you head out on the water, and change the gear lube in the stern drive at least once a year (if not more).

If you have any questions about stern drive maintenance or repair, please call Marine Parts Source at (866)388-0390. And don't forget to order all the components you need for proper stern drive maintenance from us online! We stock parts for MerCruiser, OMC and Volvo Penta stern drives - just bring your serial and/or model number and we'll do the rest!