Arco WP001 Mercury Replacement Water Pump
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Product Description
The ARCO WP001 is a complete premium replacement brass seawater pump for compatible 2000 and newer Mercury MerCruiser V6 and V8 engines. It replaces the engine-driven raw-water pump responsible for drawing lake or seawater into the cooling system. The WP001 is designed for MCM 305, 350 and 496 CID applications originally equipped with the brass seawater pump assembly.
Key Features
- ARCO part number: WP001
- Complete replacement seawater pump assembly
- Fits compatible 2000 and newer Mercury MerCruiser engines
- Designed for engines equipped with the brass raw-water pump
- Supported V6 and V8 applications
- Covers 305, 350 and 496 CID engine families
- New premium replacement assembly—not a rebuilt pump
- Every ARCO pump is tested before packaging
- UPC / GTIN: 693006030098
Engine Compatibility
Confirmed applications include compatible 2000 and newer MCM V6 and V8 engines equipped with the brass seawater pump, including:
- MerCruiser V6 applications
- MerCruiser 305 CID / 5.0L V8 applications
- MerCruiser 350 CID / 5.7L V8 applications
- MerCruiser 496 CID / 8.1L V8 applications
Fitment depends on the installed brass seawater-pump configuration and original pump number. Engine displacement alone is not sufficient because accessory-drive and cooling-system arrangements can vary between model years and serial ranges.
Serial Number Fitment Notice
Before ordering, confirm that the engine is a 2000-or-newer Mercury MerCruiser application using the brass seawater pump and that the original assembly matches one of these numbers:
- Mercury 8M0139984
- Mercury 8M0118062
- Mercury 862914A13
- Sierra 18-3160-1
Do not confuse the WP001 with the older ARCO WP004 V-belt, two-piece MerCruiser pump. The WP001 is intended for the later brass seawater-pump configuration.
When This Part Needs Replacement
Replace the complete seawater pump when:
- Cooling-water discharge becomes weak
- Engine temperature rises despite a serviceable impeller
- The pump housing is internally scored or corroded
- Water leaks from the shaft seal
- The shaft develops excessive movement
- The bearing becomes noisy or rough
- The pump repeatedly loses prime
- The housing, pulley or mounting points are damaged
- Impeller replacement no longer restores proper pumping performance
A new impeller cannot compensate for a badly worn housing, damaged shaft, failed seal or loose bearing.
Installation Notes
- Confirm the engine serial number and original pump reference before removal.
- Close the seawater intake seacock or otherwise isolate the water supply.
- Disconnect the battery before working around the belt drive.
- Record the original belt routing and hose locations.
- Inspect the drive belt, pulley, hoses and clamps while the pump is removed.
- Clean all hose connections and mounting surfaces.
- Transfer any required pulley or mounting hardware according to the service procedure.
- Align the pump and pulley carefully before tensioning the belt.
- Prime the replacement pump before initial startup where required.
- Restore the seawater supply before starting the engine.
- Check immediately for leaks, correct belt tracking and strong exhaust-water discharge.
Professional installation is recommended when pulley transfer, belt alignment or cooling-system diagnosis is required.
Alternate / Replacement Part Numbers
- ARCO: WP001
- Mercury MerCruiser: 8M0139984
- Mercury MerCruiser: 8M0118062
- Mercury MerCruiser: 862914A13
- Quicksilver: 8M0139984
- Quicksilver: 8M0118062
- Sierra: 18-3160-1
- UPC / GTIN: 693006030098
Compatible & Related Parts
When servicing the MerCruiser brass seawater pump, consider these related parts:
- Mercury MerCruiser Seawater Pump Impeller Kit 8M0137219 – OEM impeller kit for brass pump service
- Mercury MerCruiser Quicksilver Impeller Kit 8M0104229 – OEM impeller kit
- Sierra 3160-1 MerCruiser Sea Water Pump – Brass – alternative brass pump assembly (Sierra 18-3160-1)
- ARCO WP004 MerCruiser Replacement Water Pump – older V-belt two-piece MerCruiser pump variant
Parts Desk Insight
The most important identification detail is the brass seawater-pump configuration. The WP001 covers several later MerCruiser V6 and V8 applications, but it should still be matched by the original pump number or engine serial-number diagram rather than displacement alone.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.