Arco WP003 Volvo Replacement Water Pump
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You have 30 days to request a return. All sale items are final sale.
Product Description
The ARCO WP003 is a complete premium replacement engine-cooling water pump for compatible Volvo Penta, Indmar and GM-based marine engine applications. It is designed as a direct replacement for Volvo Penta water pump 3860703 and Sierra 18-3587-1, providing a complete replacement assembly when the original pump is leaking, worn or no longer circulating coolant effectively.
Key Features
- ARCO part number: WP003
- Complete replacement engine water pump
- Fits compatible Indmar Ford 351 applications
- Fits most supported GM-based marine engines
- Replaces Volvo Penta 3860703
- Cross-references Sierra 18-3587-1
- Manufactured as a premium OEM-style replacement
- Each ARCO pump is tested before packaging
- Covered by the manufacturer's ARCO Assurance warranty under its published terms.
Engine Compatibility
Confirmed application references include:
- Indmar Ford 351
- Most compatible GM-based marine engines
- Volvo Penta installations originally equipped with water pump 3860703
Fitment is based on the original pump number and engine configuration. Engine make or displacement alone is not sufficient because similar Ford- and GM-based marine engines may use different pulleys, mounting patterns or cooling-system arrangements.
Serial Number Fitment Notice
Before ordering, confirm that the existing pump or engine parts diagram identifies one of the following:
- ARCO WP003
- Volvo Penta 3860703
- Sierra 18-3587-1
The WP003 is identified as a Volvo Penta replacement because it crosses directly to Volvo Penta 3860703, while its supported applications also include Indmar Ford 351 and most compatible GM-based marine engines. Verify the original pump number, pulley arrangement and engine serial number before installation.
When This Part Needs Replacement
Replace the water pump when:
- Coolant leaks from the pump shaft, seal or housing
- The pulley develops noticeable movement or wobble
- The bearing becomes noisy
- Engine temperature rises despite adequate coolant
- Coolant circulation becomes weak or inconsistent
- The housing is cracked or heavily corroded
- The pump shaft binds or becomes difficult to turn
- The original pump has reached the end of its service life
A leaking shaft seal or loose bearing usually indicates that the complete pump assembly should be replaced rather than repaired.
Installation Notes
- Disconnect the battery before beginning service.
- Allow the engine to cool completely.
- Drain the cooling system to a level below the pump.
- Record the belt routing before removing the original pump.
- Inspect the drive belt, pulley and mounting hardware.
- Clean the engine's mounting surface thoroughly.
- Install the correct gasket or sealing components required by the engine service procedure.
- Tighten mounting hardware evenly to the specified torque.
- Align the pulley with the other belt-driven accessories.
- Refill the cooling system with the specified coolant mixture.
- Bleed trapped air according to the engine manufacturer's procedure.
- Run the engine and inspect for leaks, correct belt tracking and stable operating temperature.
Professional installation is recommended when pulley transfer, belt alignment or cooling-system bleeding is required.
Alternate / Replacement Part Numbers
- ARCO: WP003
- Volvo Penta: 3860703
- Sierra: 18-3587-1
Compatible & Related Parts
When servicing the Volvo Penta raw-water cooling system, consider these related parts:
- Volvo Penta Impeller Kit 3588475 – genuine OEM raw-water pump service kit
- Volvo Penta Impeller Kit 22994993 – raw-water pump service kit
- Volvo Penta Impeller Kit 21951352 – raw-water pump service kit
- Volvo Penta Raw Water Pump Impeller Puller Screw 3843949 – impeller removal tool
- Sierra Marine Water Pump Kit 18-3217 – related marine water pump kit
Parts Desk Insight
Match this pump by the original part number rather than by the “Ford 351” or “GM” description alone. Marine engine manufacturers often use different accessory arrangements on otherwise similar base engines, so confirming Volvo Penta 3860703 or Sierra 18-3587-1 is the safest fitment check.
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.