Cummins QSK19 Marine Engine Parts – Raw Water Pump and Marine Cooling System Components

The Cummins QSK19 is a modern evolution of the proven K-series architecture, designed for demanding marine applications such as offshore supply vessels, harbor tugs, passenger ferries, dredgers, and ocean-going commercial workboats. This 6-cylinder, 19-liter engine delivers high torque and continuous-duty reliability across a wide RPM range. With electronic fuel systems, higher power density, and improved emissions compliance, the QSK19 is a critical asset in any marine engine room.

Just like its predecessors, the QSK19 relies heavily on a properly functioning raw water cooling system. Raw seawater must circulate efficiently through the heat exchanger and wet exhaust system to prevent overheating and premature engine wear. This guide provides an in-depth look at the full range of QSK19 marine cooling components—including raw water pumps, impellers, thermostats, zinc anodes, strainers, hoses, and clamps—ensuring your vessel stays on course.

Raw Water Pumps for Cummins QSK19

Marine Raw Water Pump – Flanged 2" Port, High-Capacity Flow

The primary component of the QSK19 marine cooling system is the raw water pump, engineered to deliver consistent seawater circulation under heavy engine load. The QSK19 pump features a flanged 2-inch port design and is constructed from marine-grade bronze with a stainless steel shaft for superior corrosion resistance.

Features:

• Designed specifically for QSK19 marine propulsion and auxiliary engines

• 2” flanged inlet and outlet ports ensure leak-proof, high-flow marine connections

• High-output impeller design optimized for wet exhaust and intercooler requirements

• Robust housing to endure long-term saltwater exposure

• Mechanical drive compatibility with front gear train or auxiliary shaft

This pump ensures continuous seawater flow to the engine’s aftercooler, heat exchanger, fuel cooler, and exhaust manifold, maintaining critical operating temperatures even under full load.

Bidirectional Marine Water Pump – Reversible Rotation Option

For flexible installation configurations, Diesel Pro Power also offers a bidirectional raw water pump option. This pump is ideal for vessels with unique mounting clearances or custom-engineered engine bays.

Advantages:

• Compatible with both clockwise and counterclockwise engine rotation

• Maintains full pump efficiency regardless of orientation

• Bronze and stainless steel marine construction resists corrosion

• Suitable for QSK19 and KTA19 platforms

Reversible pumps reduce the need for variant stocking, simplify spare part logistics, and allow easy retrofitting in non-standard marine engine layouts.

QSK19 Impeller Options – The Heart of the Raw Water Pump

High-Capacity Neoprene Impeller for Marine Use

The impeller is the moving force behind seawater circulation. QSK19 impellers are precision-molded from high-durability neoprene, designed to withstand:

• Constant rotation at varying RPMs

• Sediment, silt, and minor marine debris

• Harsh saltwater conditions

Impeller Specifications:

• Neoprene rubber formulation for abrasion resistance

• Stainless steel keyed hub for slip-free mounting

• Fast priming capability and minimal cavitation

• Ideal fit with QSK19 pump housing and shaft geometry

Regular inspection of the impeller—especially during haul-outs or 500-hour maintenance cycles—is essential for avoiding engine overheating due to degraded flow or impeller wear.

Thermostats and Internal Cooling Components for QSK19

QSK19 Thermostat – Precision Engine Temperature Regulation

The QSK19 uses a marine-optimized thermostat to regulate coolant temperature inside the engine block. The thermostat controls flow through the heat exchanger circuit and opens when internal temperatures exceed approximately 175°F.

Key Features:

• Fast-reacting thermal design to prevent thermal stress

• Marine-grade brass and stainless steel construction

• OEM-style fit for direct replacement

• Available in vented and non-vented designs based on system type

A faulty or sluggish thermostat can cause erratic engine temperatures or reduce efficiency under load—especially in tropical or high-latitude marine zones.

Thermostat Gaskets and Seals – Leak-Proof Fit for Marine Vibration

Thermostats on QSK19 engines must be resealed during every replacement. Diesel Pro Power offers all the necessary:

• Thermostat-to-housing gaskets

• Water outlet seals

• Composite gaskets rated for marine temperature and pressure cycles

Always inspect gasket surfaces and housing alignment to prevent minor leaks that can cause air intrusion or coolant loss in rough seas.

Zinc Anodes – Sacrificial Protection for Marine Cooling

Heat Exchanger Zinc Anodes – Corrosion Defense for QSK19

Electrolysis is a constant threat to any marine engine using seawater for cooling. Zinc anodes act as sacrificial metal, absorbing corrosive electrical charges and preserving the integrity of pumps, coolers, and pipework.

Available Options:

• 3/8” and 1/2” NPT zinc plugs for standard QSK19 cooler ports

• High-purity zinc for maximum sacrificial performance

• Direct fit for fuel coolers, oil coolers, aftercoolers, and raw water pumps

Replace zincs at every major service interval—or sooner in warm, brackish waters with high mineral content. Neglecting zinc replacement can lead to premature failure of critical heat exchange surfaces.

Marine Intake Water Strainers for QSK19 Cooling Systems

Pre-Pump Strainers – Blocking Debris Before It Hits the Pump

Before seawater reaches the raw water pump, it should pass through a high-capacity intake strainer. These filters protect impellers and internal cooling passages from marine growth, sand, seaweed, and shell fragments.

Available Configurations:

• 1" to 2.5" inlet/outlet sizes

• Stainless steel basket with fine mesh screen

• Marine bronze or reinforced polymer housing options

• Clear lid for quick inspection

Strainers prevent expensive downtime by catching harmful debris before it can damage rotating components or clog exchanger tubes.

Silicone Coolant Hoses – High-Temperature Routing for QSK19

The internal coolant system of the QSK19 relies on flexible yet durable hoses that can withstand extreme temperatures and prolonged engine operation.

Marine-Grade Silicone Hose Options:

• Available in inside diameters from 1” to 4”

• Reinforced 4-ply silicone construction

• UV, oil, and coolant-resistant

• Capable of withstanding up to 500°F and 150 PSI

• Sold by the foot for custom installations

Silicone hoses outlast traditional rubber and resist degradation from saltwater spray, engine oil, and coolant additives. They're ideal for long-term marine reliability.

Marine Hose Clamps – Stainless Steel, High-Torque

Clamps are the final line of defense in your cooling system. Without proper retention of hose ends, even the most rugged marine engine can suffer leaks.

Heavy-Duty Clamps Include:

• Constant-torque stainless steel bands

• Marine-rated worm gear design

• Smooth interiors to avoid hose scoring

• Available for hose sizes 9/16” through 3”

These clamps resist vibration, corrosion, and loosening under pressure fluctuations—perfect for QSK19 installations in commercial-grade engine bays.

Marine Impeller Puller Tool – For Tight-Space Service

QSK19 engine compartments often have limited access, especially around the raw water pump. Diesel Pro Power provides a purpose-built marine impeller puller that helps remove stuck impellers without damaging shafts or housings.

Tool Benefits:

• Compact grip fits inside tight housing cavities

• Ergonomic handle for manual leverage

• Durable coated finish resists marine corrosion

• Compatible with KTA19, QSK19, and other Cummins marine pumps

An essential tool for fleet mechanics and service crews working on live vessels or in drydock.

Why Raw Water Cooling Matters for QSK19 Marine Engines

While internal coolant keeps your engine block regulated, raw seawater does the heavy lifting—transferring heat away from the fuel cooler, oil cooler, heat exchanger, and wet exhaust manifold. If raw water flow is interrupted for even a few minutes at operating RPM, serious engine damage can result.

Maintaining your QSK19 raw water system means:

• Preventing catastrophic overheating

• Preserving turbocharger and exhaust components

• Extending cylinder liner and piston life

• Complying with marine emissions and reliability standards

A properly maintained cooling system supports long hours of high-load operation, whether you're towing, pushing, dredging, or carrying passengers.

Trusted by 40,000+ Marine Customers Worldwide

Diesel Pro Power has earned the trust of captains, engineers, and fleet managers across 180+ countries by providing reliable marine parts and technical expertise. When it comes to Cummins QSK19 marine cooling systems, we stock every major part—from pumps and impellers to gaskets and zincs—backed by fast shipping and expert service.

Our customers choose us because:

• We stock only precision-fit parts for Cummins marine engines

• Every part is selected for high corrosion resistance and thermal reliability

• Our support team understands marine cooling systems, inside and out

Whether you’re outfitting a new vessel or servicing a workhorse QSK19 already in the water, Diesel Pro Power delivers the cooling components you need to stay operational, safe, and compliant.