Outboard Maintenance: Protecting Cowl Seals and Alternator Belts
June 2026: Mercury recently released a new service advisory regarding the use of Corrosion Guard on outboard engines.
When performing routine powerhead maintenance on Mercury outboard engines from 6 HP EFI through 600 HP V12, specific care should be taken when applying anti-corrosion sprays.
The Risk
Allowing Corrosion Guard or similar anti-corrosion lubricants to contact the top cowl seal can cause the rubber to swell and expand. This may prevent the cowl from seating correctly, allowing water to penetrate the powerhead compartment.
Overspray on the alternator drive belt or pulleys can also cause the belt to slip, deteriorate, or become damaged.
Proper Saltwater Cleaning and Protection Procedure
- Remove the top cowl and flywheel cover.
- Inspect the powerhead and powerhead components for any salt buildup.
- Rinse any salt buildup from the powerhead components using fresh water. Keep the water stream completely away from the air intake and alternator.
- Dry. Let the powerhead and components thoroughly.
- Apply Quicksilver or Mercury Precision Lubricants Corrosion Guard strictly to external metal surfaces of the powerhead and powerhead components.
Important: Mask or avoid the alternator drive belt, belt pulleys, and cowl seals entirely. The alternator drive belt may slip or become damaged if it is coated with lubricant or Corrosion Guard spray. Cowl seals may also be damaged due to expansion or swelling if coated with lubricant or Corrosion Guard spray.
If your cowl seal is already swollen or failing to seat properly, use your engine serial number to locate a replacement cowl seal here:
Mercury Marine Parts Lookup Drawings