Cummins 4-Stroke 170HP Marine Engine Parts

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This page supports Cummins 4‑Stroke 170 HP marine diesel engines and helps you find compatible parts and practical service information. Below you’ll find maintenance tips, frequently replaced components, and troubleshooting guidance. You can also browse our main Cummins-related parts categories, and at the bottom of the page you’ll find a quick way to start browsing parts for this engine. On collection pages, use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

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How to Identify Your 170 HP Model

Find the engine dataplate: typically on the rocker cover, front gear housing, or starboard side of the block. Record the full engine serial number.
Note the CPL (Critical Parts List) if present. The CPL and serial number determine filter part numbers, belt sizes, seawater pump style, and other service components.
Confirm fuel system type: mechanical B‑series (6BT/6BTA) vs. electronic common‑rail (QSB). Many 170 HP ratings are mechanical B‑series; parts differ by platform.
Check marinization details (heat exchanger, aftercooler, seawater pump orientation) as these affect anodes, pump kits, and hose routing.

Engine Platform Overview

Cummins B‑Series 5.9 (6BT/6BTA) — 170 HP

Feature	Description
Configuration	Inline‑6, 4‑stroke diesel, mechanical fuel system; heat‑exchanger cooled, seawater pump driven off front gear.
Common Models	Often labeled as 6BT5.9‑M or 6BTA5.9‑M (ratings vary by CPL/marinization).
Advantages	Proven durability, simple mechanical service, broad parts availability, excellent torque for cruising.
Notes	Many filters and pump kits are CPL‑specific. Seawater pumps and anodes differ by heat‑exchanger/aftercooler setup; verify by serial/CPL.

QSB Common‑Rail (5.9/6.7) — General Reference

Feature	Description
Configuration	Inline‑6, 4‑stroke diesel with electronic common‑rail injection and ECU control.
Common Models	QSB5.9 or QSB6.7 marine variants. Ratings vary widely; some repowers may be detuned near 170 HP.
Advantages	Refined operation, strong mid‑range torque, improved fuel efficiency and diagnostics via ECU.
Notes	Filters, sensors, and belts differ from mechanical B‑series. Always match parts by serial and calibration ID.

Routine Maintenance & Service Parts

Intervals below are common guidelines for marine diesels; always follow your official Cummins service manual and local operating conditions.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	Every 100 hours or annually	Use marine‑grade diesel oil per spec; warm engine before draining for best results.	Oil Filters
Primary/secondary fuel filters	Every 200 hours or annually	Replace both water‑separating (primary) and on‑engine (secondary) elements; prime system after service.	Fuel Filters
Air filter	Inspect 200 hours; replace as needed	Check for restriction or salt spray contamination to prevent black smoke and power loss.	Air Filters
Seawater pump impeller/kit	Every 200 hours or 1–2 seasons	Replace earlier if stream weakens or after dry‑run/overheat; inspect cam plate and cover.	Water pumps
Anodes (HX/aftercooler)	Inspect every 3 months; replace as needed	Match anode material to water type (zinc—salt, aluminum—brackish, magnesium—fresh).	Anodes
Drive belts	Inspect 100 hours; replace if cracked/glazed	Check tension and alignment; squeal or low voltage may indicate belt slip.	Belt

*Intervals are typical guidelines; adjust based on hours, load, and environment.

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Overheat alarm or weak discharge from exhaust	Inspect seawater strainer for debris, verify impeller condition, check belt tension to circulation pump, confirm intake screen is clear.	Water pump kit/impeller, thermostat, intake screen, hoses, anodes.
Poor acceleration or low WOT RPM	Replace fuel filters, check for air restriction, verify throttle linkage; if turbocharged, inspect charge‑air hoses for leaks.	Fuel filters, air filter, hoses, belts.
Hard starting or rough idle	Confirm battery voltage, prime/bleed fuel system, check lift pump output, inspect for fuel leaks or air intrusion.	Fuel filters, hoses, starter.
Excessive black smoke	Check propeller load, air filter restriction, soot/salt in exhaust elbow, and fuel injector condition.	Air filter, exhaust elbows, injectors, propeller.
Rapid anode consumption or rusty water in HX	Verify correct anode material, check for stray current corrosion, and inspect bonding/grounds.	Anodes, hoses, sensors/grounds.

FAQs

Are parts interchangeable across different years or platforms?

Not reliably. Cummins parts are tied to the engine serial number and CPL. Mechanical 6BT/6BTA and electronic QSB engines often use different filters, belts, pumps, and sensors. Verify by serial/CPL before ordering.

When should I replace the seawater pump impeller?

Every 200 hours or 1–2 seasons is typical, sooner if the pump is run dry, debris is found in the strainer, or discharge weakens. Always inspect the cam plate and cover for scoring.

How often should fuel and engine oil filters be changed?

Oil and filter are commonly serviced every 100 hours or annually. Fuel filters are commonly replaced every 200 hours or annually, or immediately if water/contamination is detected.

What information do you need to confirm compatibility?

Please provide the engine serial number, CPL, fuel system type (mechanical vs. common‑rail), and details of the marinization (heat exchanger/aftercooler). Photos of the dataplate and the part you are replacing are very helpful.

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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.