Mercury - Water Pump Upper Repair Kit EFI FourStroke Cooling System Marine-Grade Service Kit 8M0094529. Overview. A healthy cooling system is one of those things you don't brag about-you just quietly depend on it. When you're trimmed out and cruising, the last thing you want in the back of your mind is temperature creeping up or a weak telltale stream. Outboards are happiest when the cooling system is tight, sealed, and moving water the way it should, every single trip.. This Mercury Marine part