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General Motors 4-Stroke 330HP Marine Engine Parts

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This page supports owners of General Motors 4‑Stroke 330HP marine engines used in popular sterndrive/inboard packages. Use it to find compatible replacement parts, routine service guidance, maintenance tips, and troubleshooting steps. You can also browse our main MerCruiser collection for GM‑based packages, and scroll to the bottom of this page to start browsing parts by category. On the collection pages, use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category/section.

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How to Identify Your 330HP Model

  • Locate the engine serial/ID tag: commonly found on a valve cover, flame arrestor bracket, or flywheel housing. Sterndrive packages also have a separate drive/transom assembly serial tag.
  • Decode the model suffix: it may indicate carbureted vs. EFI, cooling type (raw water vs. closed cooling), and accessory configurations that affect alternators, starters, and pumps.
  • Confirm platform details: GM small‑block V8 (5.7L‑class) 4‑stroke with marine‑rated, ignition‑protected components. Accessory mounts and exhaust pieces can differ between MerCruiser and Volvo Penta packages.
  • Note that automotive crate engines with similar power ratings are not automatically marine‑rated. Always verify marine suitability and serial/drive information before ordering parts.

Engine Overview

GM Small‑Block V8 (approx. 5.7L / 350 cu in) – 4‑Stroke

Feature Description
Configuration V8, iron block/heads (varies), typically 350 cu in with marine fuel and ignition systems; carbureted or EFI depending on package.
Common Models Seen in MerCruiser 5.7/350‑class and Volvo Penta 5.7 Gi/GXi‑class sterndrive/inboard packages (exact specs vary by year and options).
Advantages Strong low‑ to mid‑range torque, broad parts availability, well‑understood service procedures.
Notes Marine variants require ignition‑protected electrics and seawater‑compatible components. Some GM crate engines around 330 HP are not intended for marine use; verify serial/model details for correct marine parts.

Routine Maintenance & Service Parts

Intervals below are typical guidelines. Always follow the official service manual for your specific engine/drive.

Item Interval* Remarks Parts Link
Engine oil + filter Every 100 hours or annually Use marine‑rated oil and the correct filter for your package. MerCruiser Oil Filters
Gear oil (sterndrive) Every 100 hours or annually Inspect for water intrusion/metal. Replace crush washers/seals during service. Lower Unit Seal Kits
Spark plugs Inspect every 100 hours; replace as needed Gap to spec; replace if fouled or worn. Spark plug
Fuel filter / water separator Every 100 hours or each season Drain or replace more often with poor fuel quality. MerCruiser Fuel Filters
Raw‑water pump impeller Every 2 seasons or 200 hours Shorten interval in sandy/silty water or with weak telltale/overheat alarms. MerCruiser Impellers
Anodes (zinc/aluminum/magnesium) Inspect quarterly; replace when 50% depleted Choose alloy for your water (salt/brackish/fresh). Maintain bonding/grounds. MerCruiser Anodes

Frequently Used Parts Categories

Common Symptoms & Quick Checks

Symptom Check First Related Parts
Weak water stream / overheat alarm Inspect intake screens, raw‑water pump impeller, hoses, and thermostat. Impeller kit, water pump, thermostat, anodes
Poor acceleration / power loss Check prop condition/pitch, fuel filter/water separator, spark plugs, and timing. Propeller, fuel filter, spark plugs
Hard starting / rough idle Verify battery state, starter/cranking speed, fuel quality, and vacuum leaks. Starter, fuel filter, gaskets, spark plugs
Gearcase/drive noise or metal in gear oil Inspect gear oil color/odor, drain plug magnets, and prop‑shaft seals for fishing line damage. Lower unit seal kit, bearings, gaskets

FAQs

Are parts interchangeable between different years or packages?

Not always. Accessory drives, ignition, fuel delivery (carb vs. EFI), and cooling setups differ by year and by MerCruiser vs. Volvo Penta packages. Verify engine serial and drive/assembly serial numbers before ordering.

When should the raw‑water impeller be replaced?

Typically every 2 seasons or 200 hours, whichever comes first. Shorten the interval in hot, silty, or sandy conditions, or if you notice weak cooling flow or overheat warnings.

How often should sterndrive gear oil be changed?

As a rule of thumb, every 100 hours or annually. Always inspect for water intrusion or metal on the drain plug magnets during service.

What information do you need to confirm part compatibility?

Please provide the engine serial number, the sterndrive/transom assembly serial number, fuel system type (carb/EFI), and any known model designation (e.g., 5.7‑class). Photos of the nameplate and the part you’re replacing are very helpful.

Ready to find the parts you need? Browse our main MerCruiser or Volvo Penta collections to locate components 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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