Indmar 4-Stroke 340HP Marine Engine Parts
(5 products)
This page supports Indmar 4‑Stroke 340 HP marine engines with quick ways to locate compatible parts and service information. Below you’ll find maintenance tips, common replacement part categories, and troubleshooting guidance. You can also browse our main parts collections for service kits and essentials. Scroll down to start exploring parts for this engine, and remember that on collection pages you can use the Filter & Sort controls to narrow by horsepower, year range, and part category.
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How to Identify Your 340HP Model
- Locate the engine ID/serial plate on the intake/plenum, valve cover, or bellhousing area; some models have the tag near the starboard engine mount. Record the full serial and ECM calibration if present.
- Model designations may include displacement and control/EFI details (e.g., 5.7L MPI). Suffixes can indicate alternator output, cooling type (raw vs. closed), or emissions package.
- Distinguish platforms by intake and accessory layout: GM‑based 5.7L V8 (common for ~340 HP) versus later large‑displacement V8s (6.0/6.2). Note thermostat housing style and raw‑water pump type for parts matching.
- For 4‑stroke models, confirm oil filter thread/diameter and belt routing; these drive compatibility for filters, serpentine belts, and tensioners.
Engine Overview
Indmar V8 EFI 4‑Stroke (~340 HP “Monsoon 340” class)
| Feature |
Description |
| Configuration |
GM‑based 5.7L V8, multi‑port EFI, marine‑tuned ignition and cooling; raw‑water or closed‑cooling variants. |
| Common Models |
340 HP EFI 5.7L V8 packages used widely in tow‑sport boats; verify by serial and ECM label. |
| Advantages |
Strong mid‑range torque for towing, broad service parts availability, straightforward annual service. |
| Notes |
Match raw‑water pump impeller style, thermostat temperature, and belt/pulley type. Confirm oil filter size and fuel filter/regulator spec for your build year. |
Routine Maintenance & Service Parts
Intervals below are general guidelines for 4‑stroke inboard/tow‑sport use. Always follow the official Indmar service manual for your serial number and local operating conditions.
| Item |
Interval* |
Remarks |
Parts Link |
| Engine oil + filter |
50–100 hours or annually |
Use marine‑rated oil and the correct filter thread/height. Change sooner for heavy towing or dusty conditions. |
Oil Filters |
| Transmission/V‑drive fluid |
100 hours or annually |
Use the specified ATF or gear oil for your transmission or V‑drive; check color and smell for overheating. |
Service & Maintenance Kits |
| Spark plugs |
100 hours or annually |
Match heat range and gap for your ECM calibration; inspect leads/boots. |
Spark Plugs |
| Fuel filter / water separator |
100 hours or annually |
Replace more frequently if poor fuel quality is suspected; prime system after service. |
Fuel Filters |
| Raw‑water pump impeller |
Annually or every 100 hours |
Replace sooner if run dry or after sand/silt ingestion; keep a spare onboard. |
Impellers |
| Thermostat |
Inspect annually; replace 2–3 years |
Match rated temperature (commonly 143–160°F depending on package). |
Gaskets & Sealing |
| Anodes (engine/gear cooler) |
Every 50 hours; replace when 50% consumed |
Use zinc (salt), aluminum (brackish), or magnesium (fresh) as appropriate. |
Anodes |
| Serpentine belt & tensioner |
Inspect each service; replace 2–3 years |
Check for glazing or cracking; verify alignment after alternator or pump work. |
Belts |
Frequently Used Parts Categories
Common Symptoms & Quick Checks
| Symptom |
Check First |
Related Parts |
| Weak water stream or overheat alarm |
Inspect raw‑water strainer for debris, check impeller condition, verify thermostat operation and intake screen. |
Water pump impeller kit, thermostat, intake screen, hoses/clamps |
| Poor acceleration or power loss |
Replace fuel/water separator, check fuel pressure and injector spray, inspect spark plugs and ignition leads. |
Fuel filter, fuel pump, injectors, spark plugs/wires |
| Hard starting or rough idle (hot or cold) |
Test battery and grounds, look for vacuum leaks, verify IAC/idle air strategy and clean throttle body. |
Starter, sensors (IAC/MAP), gaskets, fuel filter |
| Transmission/v‑drive noise or contaminated fluid |
Check fluid level and color; inspect coolers and lines for leaks; change fluid and filter if due. |
Service kit, hoses, oil cooler, clamps |
FAQs
Are parts interchangeable between different years or engine packages?
Some service items (spark plugs, belts, filters) overlap across years, but cooling hardware, fuel components, sensors, and brackets can vary by serial and cooling/intake configuration. Confirm by engine serial and component casting/label.
When should I replace the raw‑water pump impeller?
Annually or every ~100 hours, whichever comes first. Replace immediately after any dry‑run event or if blades show set, cracks, or missing tips.
How often should transmission or V‑drive fluid be changed?
Typically every season or ~100 hours, and any time fluid appears dark, smells burnt, or is contaminated with water/metal. Use only the fluid specified for your drive.
What information helps confirm part compatibility?
Provide the engine serial, model/displacement, ECM calibration if available, cooling type (raw vs. closed), and clear photos of the part and mounting area.
Ready to service your Indmar 4‑Stroke 340 HP engine? Browse our main parts collections to locate filters, impellers, ignition, and cooling components by category.
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Not sure about your exact model? Send us a clear photo of the nameplate and the part you need and we’ll help verify compatibility.
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