Indmar 400HP 4-Stroke Marine Engine Parts

(2 products)

This page focuses on Indmar 4‑Stroke 400HP inboard marine engines. It helps you identify compatible parts and find key service information, including maintenance tips, common replacement items, and troubleshooting guidance. You can also browse our main engine parts collections for Indmar‑compatible categories. Scroll to the bottom of this page to start browsing parts. On the collection pages, use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category.

Browse Parts Collections

How to Identify Your 400HP Model

Locate the engine serial/nameplate: commonly on the starboard side of the block near the bellhousing, or on an Indmar tag near the intake/ECM. Record the full serial and model name.
Read the model designation and suffixes: they may indicate platform (GM‑based 6.0L vs Ford‑based 6.2L “Raptor”), emissions equipment (catalyst/ETXCAT), and control calibration.
Distinguish platforms: GM‑based 6.0L engines typically use cast aluminum manifolds and a conventional accessory layout; Ford‑based Raptor 400 6.2L often has distinct valve covers, belt routing, and “Raptor” labeling.
Confirm drive details: note transmission/V‑drive model and cooler type; these affect service parts like fluids, coolers, and mounts.

Platform Overview

GM 6.0L V8 (Approx. 400 HP)

Feature	Description
Configuration	V8 EFI 4‑Stroke, raw‑water or heat‑exchanger cooled, electronic ignition/ECM.
Common Models	Indmar 6.0L GM‑based 400 HP variants (L96/LY6 family); often seen in mid‑2010s inboards.
Advantages	Proven small‑block architecture, strong mid‑range torque, widely available service parts.
Notes	Some versions use catalytic (ETXCAT) exhaust manifolds. Verify fuel pump style, plug wire routing, and thermostat housing when selecting parts.

Ford 6.2L V8 “Raptor 400”

Feature	Description
Configuration	V8 EFI 4‑Stroke (Ford‑based 6.2L), electronic throttle, serpentine belt drive, catalyst exhaust on many models.
Common Models	Indmar Raptor 400 installations in V‑drive towboats (mid‑2010s and newer).
Advantages	Excellent low‑end pull for watersports, robust cooling components, modern emissions hardware.
Notes	Belts, sensors, and exhaust components differ from GM‑based 6.0L. Match parts using engine serial and platform (Raptor vs GM 6.0L).

Routine Maintenance & Service Parts

Intervals below are general guidelines for modern 4‑stroke inboard V8s. Always follow your official Indmar service manual for model‑specific procedures and intervals.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	50 hrs (initial), then every 100 hrs or annually	Use marine‑rated oil meeting the engine spec; change more often in severe duty.	Oil Filters
Transmission/V‑drive fluid	100–200 hrs or annually (per drive model)	Verify fluid type for your gearbox/V‑drive and change the cooler O‑rings if required.	Service & Maintenance Kits
Spark plugs	200–300 hrs, or if misfire/starting issues occur	Check gap and plug type based on platform (GM 6.0L vs Raptor 6.2L).	Spark Plugs
Fuel filter / water separator	100 hrs or annually	Replace more often with ethanol or if stored long periods.	Fuel Filters
Raw‑water pump impeller	Annually or every 100 hrs	Replace sooner if sand/silt use, overheating, or weak flow is observed.	Impellers
Sea strainer service	Check every outing; clean as needed	Inspect bowl O‑ring and hoses for leaks or cracks.	Hoses
Anodes (zinc/aluminum/magnesium)	Inspect monthly; replace when 50% consumed	Choose alloy for your water type (salt/brackish/fresh).	Anodes
Serpentine/accessory belt	Inspect every 50–100 hrs; replace at first sign of cracking/glazing	Raptor and GM 6.0L use different belt lengths/routing—match to platform.	Belt

Frequently Used Parts Categories

Routine Service: Service & Maintenance Kits
Oil & Filtration: Oil Filters
Fuel System: Fuel Filters and Fuel Pumps
Cooling System: Water pumps and Impellers
Ignition / Electrical: Sensors and Starters
Exhaust Components: Manifolds and Elbows
Hoses & Connections: Hoses

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Overheating or weak water flow	Inspect sea strainer for debris, raw‑water pump impeller for wear, intake screen, and thermostat operation; verify hoses and clamps.	Water pump impeller kit, hoses/clamps, thermostat, intake screen/strainer parts
Poor acceleration / power loss	Check fuel quality, replace fuel filter, verify spark plugs and plug wires, and scan for ECM fault codes (MAP/O2, etc.).	Fuel filter, fuel pump, spark plugs/wires, sensors (MAP, O2)
Hard starting / rough idle	Verify battery and cable condition, inspect IAC/throttle body cleanliness, and confirm no vacuum leaks; replace aged plugs.	Starter, sensors (IAC/TPS), spark plugs, fuel filter
MIL or beeper alarm (check engine)	Retrieve ECM codes; common items include O2 sensor performance, coolant/temp sensor, knock sensor, or catalyst efficiency (ETXCAT models).	Sensors (O2, temp, knock), wiring/connectors, manifolds/catalyst hardware

FAQs

Are parts interchangeable between GM 6.0L and Raptor 6.2L platforms?

Some service items (filters, anodes, hoses) may be similar, but many components—belts, sensors, ignition, exhaust, and cooling hardware—are platform‑specific. Always match by engine serial, model name, and platform.

When should I replace the raw‑water impeller?

As a rule of thumb, replace annually or every 100 hours. In sandy/silty water or if the engine overheated or sat dry for storage, replace sooner.

How often should transmission/V‑drive fluid be changed?

Most inboard drives call for 100–200 hours or annual changes, but fluid type and interval vary by gearbox/V‑drive model. Refer to your drive’s manual.

What information helps confirm part compatibility?

Provide the engine serial number, model name (e.g., “Raptor 400” or “6.0L 400 HP”), approximate year, transmission/V‑drive model, and photos of the nameplate and the part you’re replacing.

Ready to find parts? Browse our main engine parts collections and refine by category to match your Indmar 400HP setup.

Browse Parts Collections

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.