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OMC 5.7L 4-Stroke Marine Engine Parts

(2 products)

This page supports OMC 5.7L 4-stroke sterndrive marine engines, helping you find compatible parts and service information. Inside youll find maintenance tips, commonly replaced parts, and troubleshooting guidance. You can also browse the main Johnson/Evinrude collection. Scroll to the bottom of this page to start browsing parts for this engine. On the collection page, use the Filter & Sort controls to narrow results by model year range and part category.

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How to Identify Your 5.7L Model

  • Nameplate/serial: Check the engine block or flame arrestor tag for the GM 350 cid (5.7L) ID, and the transom assembly for the sterndrive model tag.
  • Sterndrive family: 5.7L packages from the late 1980s to early 1990s typically use the OMC Cobra sterndrive; note the drive model, gear ratio, and rotation on the tag.
  • Year cues: OMC Cobra sterndrives were common circa 1986 1993. Parts can vary by year and gearcase version, so record the exact model/serial.
  • Platform distinction: The 5.7L V8 uses the standard Cobra gearcase (not the King Cobra lower unit), and the raw-water pump/impeller is located in the upper gearcase.

Engine & Drive Platform Overview

OMC 5.7L V8 with Cobra Sterndrive

Feature Description
Configuration V8 gasoline, 4-stroke (350 cid/5.7L), typically carbureted or early EFI, mated to OMC Cobra sterndrive.
Common Models OMC/Johnson-Evinrude marine 5.7L V8 packages using Cobra drives, approx. 1986 1993.
Advantages Strong torque, broad parts availability, straightforward service for gearcase and ignition/fuel components.
Notes For 5.7L applications, use standard OMC Cobra lower-unit components (not King Cobra). Cobra water pump/impeller is located in the upper gearcase. Proper shift-cable and interrupter switch adjustment is critical for smooth engagement.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow your official service manual and local operating conditions.

Item Interval* Remarks Parts Link
Engine oil & filter 100 hrs or annually Use marine-rated oil; replace filter at each oil change. Johnson/Evinrude/OMC Service & Maintenance Kits
Gear oil (lower unit) 100 hrs or annually; after submersion Check for water (milky oil). Reseal if contamination is found. Johnson/Evinrude/OMC Lower Unit Seal Kits
Spark plugs 100 hrs or annually Inspect condition and gap; replace fouled or worn plugs. Spark Plugs
Fuel filter / water separator 100 hrs or annually; sooner with contaminated fuel Drain water bowls and replace elements regularly to prevent lean surging. Fuel Filters
Water pump impeller/kit (upper gearcase) Every 2 3 seasons or 200 hrs Replace sooner if overheat/weak flow occurs or after sandy/silty use. Johnson/Evinrude/OMC Water Pump Repair Kits
Anodes (zincs) Inspect 50 hrs; replace at ~50% depletion Match anode material to water type (salt/brackish/fresh). Johnson/Evinrude/OMC Anodes
U-joint & exhaust bellows (inspect) Annually Cracked bellows allow water intrusion leading to bearing/gear damage. Bellows
Gimbal bearing (inspect/service) Annually; replace if noisy/rough Grease at recommended intervals; replace if vibration or rumble persists. Johnson/Evinrude/OMC Bearings

Frequently Used Parts Categories

Common Symptoms & Quick Checks

Symptom Check First Related Parts
Overheat alarm / weak water flow Inspect sea-water intake screens, upper gearcase impeller condition, and thermostat. Verify proper hose routing and no kinks. Water pump kit, thermostat, intake screen/gaskets
Hard shifting or stalls on shift Confirm idle speed is per spec, check shift cable adjustment, and inspect the shift interrupter switch function. Shift cable, interrupter switch, detent parts, gear oil
Poor acceleration / power loss Check prop condition/pitch, replace fuel filter, verify ignition timing and plug condition; inspect for restricted exhaust. Propeller, fuel filter, spark plugs, anti-siphon valve
Gearcase noise / metal in oil Drain oil to inspect for water or metal; pressure/vacuum test the gearcase if contamination is found. Seals, bearings, gears, shim kit
Hard starting / rough idle Verify choke/enrichment, check for stale fuel, inspect plugs and ignition wires; for EFI/TBI, confirm clean injectors and proper fuel pressure. Spark plugs, fuel filter, fuel pump, carb kit/injector service

FAQs

Are 5.7L OMC parts interchangeable across years?

Many engine components are shared across GM 350 cid marine packages, but sterndrive and gearcase parts can vary by year and model. 5.7L applications use the standard Cobra drive rather than the King Cobra lower unit. Always confirm the exact engine and drive model/serial before ordering.

When should I replace the impeller?

As a preventative measure, replace the raw-water pump impeller every 2 3 seasons or ~200 hours. In sandy, silty, or high-temperature environments, shorten the interval. Replace immediately if you see overheat warnings or weak water flow.

How often should I change gear oil?

At least every 100 hours or annually, and any time water intrusion is suspected (milky oil), after an impact, or prior to winterization. Pressure/vacuum test the gearcase if contamination is found.

What information do you need to confirm compatibility?

Please provide engine model and serial numbers, sterndrive model (Cobra), drive gear ratio and rotation (standard or counter-rotating), and approximate model year. Photos of the nameplate and the part needing replacement also help.

Ready to find the right parts? Browse our main Johnson/Evinrude collection and refine by model details to locate compatible components for your OMC 5.7L V8.

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If youre unsure about your model, send us a photo of the nameplate and the part you need and well help verify compatibility.
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