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Mercury 4-Stroke 370HP Marine Engine Parts

(2 products)

This page is for Mercury/MerCruiser 4‑Stroke 370 HP inboard/sterndrive engines. It helps you find compatible parts and service information, including maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main MerCruiser collection. Scroll to the bottom of the page to start browsing parts for this engine, and use the “Filter & Sort” controls on the collection page to narrow by horsepower, year range, and part category.

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How to Identify Your 370 HP Model

  • Locate the engine serial number decal on the top or side of the engine (often near the flame arrestor or valve cover). For sterndrives, note the transom assembly and drive serial tags as well.
  • Record the full model/serial and any suffixes indicating cooling type (e.g., closed‑cooling “Horizon”) and emissions calibration. These details determine exact parts.
  • Identify platform: inboard (direct inboard “Horizon”) vs. sterndrive (Bravo drive). Some ignition, fuel, and cooling components differ between platforms.
  • Confirm build family: 8.1L/496 EFI V8 variants are common in this horsepower range. Many service parts overlap, but verify by serial to avoid mismatch.

Platform Overview

8.1L Horizon Inboard (Approx. 370 HP)

Feature Description
Configuration V8 8.1L EFI 4‑Stroke, typically closed‑cooling in inboard applications
Common Models Examples include “8.1L Horizon” inboard calibrations around 370 HP
Advantages Strong torque, stable idle, durable big‑block base; closed‑cooling helps corrosion control
Notes Raw‑water pump (crank‑driven) impeller is routine service; verify thermostat and anode styles by serial and cooling configuration

8.1L/496 Sterndrive (Bravo) Family – Related Platform

Feature Description
Configuration V8 8.1L EFI 4‑Stroke mated to Bravo sterndrive; raw‑water or closed‑cooling depending on build
Common Models 496‑family Bravo applications near this power range
Advantages Broad parts availability, strong mid‑range, proven drive options
Notes Service items overlap with inboard variants, but sterndrive‑specific items (bellows, anodes, gear lube) and cooling layouts vary—confirm by serial

Routine Maintenance & Service Parts

Intervals below are general guidelines; always follow the official service manual for your exact serial range and operating conditions.

Item Interval* Remarks Parts Link
Engine oil + filter Every 100 hours or annually Use marine‑approved oil; verify filter thread/length by serial MerCruiser Oil Filters
Gear lube (Bravo drive) / transmission fluid (inboard) Every 100 hours or annually Inspect for water or metal; service vent and drain seals as needed MerCruiser Service & Maintenance Kits
Spark plugs 200–300 hours or 3 years Replace sooner if fouled or misfire noted Spark Plug
Fuel filter / water separator Every 100 hours or annually Drain and check for water; replace cartridge regularly MerCruiser Fuel Filters
Raw‑water pump impeller 1–2 seasons (or sooner in sandy/silty water) Critical for cooling; inspect housing and wear plate MerCruiser Impellers
Anodes (engine/drive) Inspect every 60–90 days; replace when 50% depleted Match material to water type (zinc, aluminum, or magnesium) MerCruiser Anodes
Serpentine/accessory belt Inspect every 100 hours; replace 2–3 years Check tensioner and idlers for noise/wear Belt
Thermostat 3–5 years or if temp is unstable Choose correct temp rating for calibration MerCruiser
Bellows (sterndrive) Inspect annually; replace 2–3 years Cracks or water intrusion can damage U‑joints and gimbal Bellow

Frequently Used Parts Categories

Common Symptoms & Quick Checks

Symptom Check First Related Parts
Overheat alarm or high temperature at idle Inspect seawater strainer, intake screen, and raw‑water pump impeller; verify thermostat operation Water pump impeller kit, thermostat, anodes (block passages)
Poor acceleration / power loss Check fuel quality, water separator, spark plugs, and propeller condition/pitch Fuel filter, spark plugs, propeller, ignition components
Hard starting / rough idle Verify battery health and connections; inspect IAC/air path, fuel filter, and plugs Electrical items, fuel filter, spark plugs, sensors
Gearcase noise / metal shavings in gear lube (sterndrive) Check gear lube level/condition; inspect prop shaft for fishing line; listen for U‑joint/gimbal bearing noise Service kit, propeller, bearings, bellows

FAQs

Are parts interchangeable between 8.1L Horizon inboards and 8.1L/496 sterndrive models?

Many service items overlap, but cooling layouts, brackets, sensors, and exhaust components can differ. Always confirm by engine and (if applicable) drive serial numbers before ordering.

When should the raw‑water impeller be replaced?

Inspect annually and replace every 1–2 seasons, or sooner in sandy/silty water or if flow is reduced. Heat damage or missing vanes require immediate replacement.

How often should gear lube be changed?

For Bravo sterndrives, change every 100 hours or annually, and anytime water or metal is present. For inboards, follow the transmission manufacturer’s fluid interval.

What information helps confirm part compatibility?

Provide engine serial number, platform (inboard vs. sterndrive), cooling type (raw‑water vs. closed‑cooling), and any accessory options (alternator output, belt layout). Photos of the nameplate and the part to replace are very helpful.

Ready to find the right parts? Browse the main MerCruiser collection and refine by horsepower, year, and model.

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If you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.
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