Bi-Directional Circulating Water Pump for GM V6 and Small-Block V8 Marine Engines – Replaces 8M0113734, 8503991 and 3853850
Bi-Directional Circulating Water Pump for GM V6 and Small-Block V8 Marine Engines – Replaces 8M0113734, 8503991 and 3853850 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Bi-Directional Circulating Water Pump for GM V6 and Small-Block V8 ...
Bi-Directional Circulating Water Pump for GM V6 and Small-Block V8 Marine Engines – Replaces 8M0113734, 8503991 and 3853850 is backordered and will ship as soon as it is back in stock.
Product Details
This bi-directional circulating water pump is an aftermarket replacement for selected GM V6 and small-block V8 marine engine cooling systems. It is designed for applications using either a metal or composite timing-chain cover and is intended to replace the corresponding original pump after confirming the engine configuration, mounting pattern and original part number.
Catalog references identify this pump style with Mercury Marine 8503991 and 8M0113734, Volvo Penta 3853850, OMC 382218, 980477 and 985429, Crusader 20318 and 7142520, Pleasurecraft RA057018, and Sierra 18-3599-1 or 18-3599-2. These references are provided for identification and interchange research; verify your exact engine before ordering.
- Engine-mounted circulating water pump for applicable GM V6 and small-block V8 marine engines.
- Bi-directional design for compatible metal and composite timing-chain-cover configurations.
- Mounting gasket included for the listed pump application.
- Aftermarket replacement; not an OEM-manufactured component.
Part Number Matrix
Use the following references to compare the pump with the part removed from your engine.
| Brand or source | Reference number |
|---|---|
| Mercury Marine | 8503991 |
| Mercury Marine | 8M0113734 |
| Volvo Penta | 3853850 |
| OMC | 382218 |
| OMC | 980477 |
| OMC | 985429 |
| Crusader | 20318 |
| Crusader | 7142520 |
| Pleasurecraft | RA057018 |
| Sierra | 18-3599-1 |
| Sierra | 18-3599-2 |
Engine and Model Compatibility
Catalog information identifies the applicable engine family as GM V6 and small-block V8 marine engines, including 3.8L, 4.3L, 5.0L and 5.7L configurations associated with the 3853850 pump reference. The same pump style is listed for both metal and composite timing-chain covers.
Fitment depends on the exact engine design, cover configuration, mounting arrangement and serial or production range. A displacement or brand match alone does not confirm compatibility. Compare the original pump, pulley and mounting surface before ordering.
| Engine family | Displacement examples | Stroke | Application note |
|---|---|---|---|
| GM V6 marine engines | 3.8L, 4.3L | 4-Stroke | Applicable only where the original pump and mounting configuration match. |
| GM small-block V8 marine engines | 5.0L, 5.7L | 4-Stroke | Verify timing-chain-cover style and original pump reference. |
Technical Specifications
- Product type
- Bi-directional circulating water pump
- Application
- Selected GM V6 and small-block V8 marine engines
- Installation
- Engine mounted
- Timing-chain-cover compatibility
- Designed for compatible metal and composite cover configurations
- Replacement references
- 8503991, 8M0113734, 3853850, 382218, 980477 and 985429
- Product status
- Aftermarket replacement part
What's in the Box
- 1 x Bi-directional circulating water pump
- 1 x Mounting gasket
Installation Notes
- Disconnect the battery and allow the engine to cool completely.
- Drain the cooling system into a suitable container.
- Remove the belt and any components that obstruct access to the pump.
- Disconnect the cooling hoses and remove the original pump mounting hardware.
- Clean the engine mounting surface thoroughly and remove all old gasket material.
- Compare the replacement pump with the original part, including mounting holes, pulley alignment, ports and cover interface.
- Install the supplied gasket and replacement pump. Tighten fasteners in the manufacturer's specified sequence and to the specified torque.
- Reconnect hoses, reinstall the belt and replace any removed brackets or components.
- Refill the cooling system with the correct coolant, reconnect the battery and check for leaks and proper circulation.
Troubleshooting and FAQ
What engines is this pump intended for?
Catalog references identify this pump style for selected GM V6 and small-block V8 marine engines, including 3.8L, 4.3L, 5.0L and 5.7L applications. Confirm the original pump reference and physical configuration before purchase.
Is the pump bi-directional?
Yes. The pump is described as bi-directional and is intended for compatible engines using either a metal or composite timing-chain cover.
Is a gasket included?
Yes. One mounting gasket is included with the pump.
Does a listed engine displacement guarantee fitment?
No. Engine displacement is only an initial guide. Verify the exact engine model, production or serial range when applicable, timing-chain-cover style, mounting pattern and original part number.
Is this an OEM part?
No. This listing is for an aftermarket replacement pump. The OEM and aftermarket numbers shown above are reference numbers used to help identify the applicable pump.
What are common signs of a failing circulating water pump?
Possible symptoms include overheating, coolant leakage near the pump, abnormal bearing or pulley noise, pulley wobble, or visible damage around the pump and gasket joint. Diagnose the complete cooling system before replacing components.
Safety and Important Information
- Confirm the original part number and compare the pump's mounting and port arrangement before ordering.
- Do not rely on the brand, displacement or year alone to determine fitment.
- Do not operate the engine without the correct coolant level and a properly installed belt.
- Professional installation is recommended, especially where engine access or coolant service is difficult.
- OEM and brand names are used only to identify compatibility and replacement references.
About Sea Sierra
- Marine replacement parts — We provide aftermarket components for common marine engine and cooling-system service applications.
- Clear reference information — OEM and aftermarket numbers are displayed to help customers compare the replacement with the original part.
- Fitment-first ordering — Always confirm the engine configuration and original component before installation.
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