MerCruiser 4-Stroke 320HP Marine Engine Parts

(9 products)

This page is for MerCruiser 4‑Stroke 320HP marine engines and helps you quickly find compatible parts and service information. Inside you’ll find maintenance intervals, frequently used replacement parts, and troubleshooting tips. You can also browse the main MerCruiser collection. Scroll to the bottom of this page to start browsing parts for this engine, and on the collection page use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category.

Browse All MerCruiser Parts

How to Identify Your 320HP Model

Find the serial numbers: MerCruiser engines and drives use serial numbers rather than model codes. The engine serial tag is typically on the starboard side of the engine (near the flywheel housing or valve cover). The sterndrive has its own serial plate on the starboard side of the drive or transom assembly.
Record both engine and drive serials: Many parts depend on both the engine family (e.g., 6.2L V8) and the drive type (Alpha/Bravo). Having both serials ensures the most accurate parts match.
Induction and cooling details: Note whether your engine uses MPI/EFI and whether it’s raw‑water cooled or closed‑cooling (heat exchanger). These details affect impellers, hoses, thermostats, and anode styles.
Horsepower confirmation: 320 HP packages are commonly V8 sterndrives. If unsure, compare your serials with the service manual or contact support before ordering.

Engine Overview

MerCruiser 4‑Stroke 320HP V8 Sterndrive

Feature	Description
Configuration	V8, 4‑stroke, multi‑port fuel injection (MPI/EFI), raw‑water or closed‑cooling options, typically paired with Alpha or Bravo sterndrives.
Common Models	Examples include 6.2L V8 320 HP packages and earlier 320 HP V8 variants; exact parts depend on engine and drive serial numbers.
Advantages	Strong mid‑range torque, smooth idle, robust charging output, and broad parts availability for routine service.
Notes	Cooling, anode style, and raw‑water pump location vary by package. Always confirm using engine and drive serial numbers to avoid mismatches.

Routine Maintenance & Service Parts

Intervals below are general guidelines for 4‑stroke MerCruiser V8 sterndrives. Always follow the official service manual for your specific engine and drive.

Item	Interval*	Remarks	Parts Link
Engine Oil & Filter	Every 100 hrs or annually	Use marine‑grade oil to spec; replace filter at every oil change.	MerCruiser Oil Filters
Gear Oil (Drive)	Every 100 hrs or annually	Change more frequently if water intrusion or heavy use is suspected.	MerCruiser Service & Maintenance Kits
Spark Plugs	Inspect at 100 hrs; replace 300 hrs/3 yrs	Use correct heat range and gap; replace sooner if fouled.	Spark Plugs
Fuel/Water‑Separating Filter	Every 100 hrs or annually	Replace more often in high‑moisture or ethanol environments.	MerCruiser Fuel Filters
Raw‑Water Pump Impeller	Every 200 hrs or 2 years	Critical for cooling. Inspect annually; replace if blades set or cracked.	MerCruiser Impellers
Anodes (Corrosion Protection)	Inspect every 50 hrs; replace when 50% depleted	Choose zinc, aluminum, or magnesium to match your water type.	MerCruiser Anodes
Propeller & Hardware Check	Inspect every 50–100 hrs	Remove to check for fishing line, damaged thrust washer, and worn hub.	MerCruiser Propellers

Frequently Used Parts Categories

Routine Service Kits – MerCruiser Service & Maintenance Kits
Cooling System (Impellers) – MerCruiser Impellers
Fuel System (Filters) – MerCruiser Fuel Filters
Ignition/Electrical – Starters and Alternators
Corrosion Protection – MerCruiser Anodes
Propellers & Hardware – MerCruiser Propellers
Gaskets & Sealing – MerCruiser Gaskets

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Overheat alarm or weak water flow	Inspect intake screens, raw‑water pump impeller, hoses, and thermostat; verify debris‑free transom pickup.	Water pump impeller kit, thermostat, intake screen, anodes
Poor acceleration or power loss	Check prop damage/pitch, fuel quality, and replace the water‑separating fuel filter; verify spark plug condition.	Propeller, fuel/water‑separating filter, spark plugs
Hard starting or rough idle	Confirm battery voltage and clean connections; inspect plugs and ignition leads; check IAC/throttle body for deposits.	Spark plugs, starter, alternator, fuel filter
Gearcase noise or metal in gear oil	Drain and inspect gear lube; check for fishing line at prop shaft; evaluate seals and bearing play.	Lower unit seal kit, bearings, prop hardware
Trim won’t hold or moves slowly	Verify trim fluid level, electrical connections, and look for leaking ram seals.	Trim motor/pump, seals, wiring

FAQs

Are parts interchangeable between different 320 HP years or platforms?

Not always. Differences in induction, cooling type, emissions hardware, and the sterndrive (Alpha/Bravo) affect part selection. Use the engine and drive serial numbers to confirm compatibility.

When should the raw‑water impeller be replaced?

Inspect annually and replace every 200 hours or two years. Replace sooner if you see reduced flow, overheating, or impeller blade set/cracking.

How often should I change the drive gear oil?

At least every 100 hours or annually, and immediately after any suspected water intrusion or impact to the prop/gearcase.

What information helps confirm the correct parts?

Engine serial number, sterndrive serial number, horsepower, approximate model year, cooling type (raw vs closed), and whether your package is paired with Alpha or Bravo drive.

Ready to find the right components? Browse the main MerCruiser collection and narrow by horsepower, year, and model to locate parts for your 320 HP engine.

Shop MerCruiser Parts

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