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Mercury Outboard Parts
Shop OEM and aftermarket Mercury outboard parts for maintenance, repair, troubleshooting, and complete engine rebuild projects. Browse Mercury marine parts by system, including cooling, fuel delivery, electrical and ignition, internal engine components, lower unit parts, steering, trim, and routine service items.
Pro Marine USA carries Mercury outboard engine parts for a wide range of 2-stroke, FourStroke, EFI, Optimax, Pro XS, SeaPro, and Verado applications. Use your engine horsepower, model, serial number, or OEM part number whenever possible to confirm fitment before ordering.
Shop Mercury Outboard Parts by System
- Complete Powerheads
- Control Cables & Boxes
- Cooling System
- Cowlings & Components
- Electrical System
- Engine Oil
- Engine Rebuild Kits
- Fuel & Carburetion System
- Intake System
- Internal Engine Components
- Lower Unit Components
- Oiling System
- Paints
- Service & Oil Change Kits
- Service Manuals
- Steering Systems
- Throttle Components
- Transom & Midsection
- Trim System
- Wizard Performance Parts
Find the Correct Mercury Outboard Part
Mercury outboard parts can vary by horsepower, engine family, model year, and serial number range. If you are unsure which component fits your engine, use the OEM parts lookup to locate the original Mercury part number from an engine diagram.
Once you have the OEM part number, search Pro Marine to find available genuine Mercury and aftermarket replacement options.
Use Our OEM Parts Lookup »Common Mercury Outboard Engine Families
Pro Marine supports many Mercury outboard applications across a wide horsepower range. Always confirm the engine serial number and model information before ordering parts.
- Portable and Midrange: Mercury 2.5HP through 60HP 2-stroke and FourStroke applications
- FourStroke and EFI: common 75HP through 300HP Mercury EFI and FourStroke platforms
- Pro XS: performance-oriented Mercury Pro XS outboards across multiple engine families
- Optimax: direct-injected 2-stroke Mercury Optimax engines, commonly 75HP through 250HP
- Verado: supercharged and naturally aspirated Mercury Verado applications from 135HP through current high-horsepower platforms
- SeaPro: commercial-duty Mercury SeaPro outboards used in professional and high-hour applications
Common Mercury Outboard Repair Areas
- Overheating: inspect the water pump, impeller, thermostat, poppet valve, cooling passages, and related cooling components.
- Hard starting or rough running: inspect fuel pumps, filters, injectors or carburetors, spark plugs, coils, sensors, and intake components.
- No spark or intermittent ignition: check ignition coils, stators, switch boxes, trigger assemblies, sensors, grounds, and wiring.
- Low compression or power loss: inspect pistons, rings, cylinders, bearings, gaskets, reeds, and internal engine components.
- Lower unit noise or water intrusion: inspect seals, bearings, gears, shafts, bearing carriers, and gear lube condition.
- Trim or steering problems: inspect trim motors, pumps, hydraulic components, steering cylinders, hoses, and related rigging parts.
Why Buy Mercury Outboard Parts from Pro Marine USA?
- OEM Mercury and aftermarket replacement options for many common applications.
- Parts for maintenance, repair, engine rebuilding, lower units, electrical systems, fuel systems, steering, trim, and rigging.
- OEM diagram and part-number lookup tools to help identify the correct part before ordering.
- Dealer pricing available for qualified marine repair businesses and dealers.
- Large inventory of Mercury service parts and hard-to-find marine engine components.
- Fast weekday shipping on qualifying in-stock orders.
Frequently Asked Questions
How do I find the correct Mercury outboard part?
Use the engine horsepower, model, serial number, and year whenever available. Mercury frequently uses serial-number ranges to identify engine families, so the serial number is often the most reliable way to confirm fitment.
Can I search Mercury parts by OEM part number?
Yes. Enter the Mercury OEM part number into the Pro Marine site search to locate available OEM and aftermarket replacement options. If you do not know the part number, use the OEM parts lookup first.
Do Mercury outboard parts vary by serial number?
Yes. Many Mercury components change by serial-number range even within the same horsepower or model family. Always compare the serial range listed for the part with your engine before ordering.
Do you carry parts for Mercury Optimax and Verado engines?
Yes. Pro Marine carries parts for many Mercury Optimax, Verado, Pro XS, EFI, FourStroke, and SeaPro applications, including maintenance, fuel, electrical, cooling, internal engine, lower unit, steering, and rigging components.
Do you carry both OEM and aftermarket Mercury parts?
Yes. Pro Marine offers genuine Mercury parts along with aftermarket replacement parts for many common Mercury outboard maintenance, repair, and rebuild applications.
What Mercury outboard parts are commonly replaced during routine maintenance?
Common maintenance items include engine oil, oil filters, fuel filters, spark plugs, water pump kits, impellers, thermostats, gear lube, drain plug seals, anodes, and manufacturer-specific service kit components.
Fitment Tip: Mercury outboard parts often vary by serial-number range. Confirm your engine serial number and OEM part number whenever possible before ordering.
Pro Marine 130°F V6 Outboard Thermostat
Mercury & Mariner 2.5L / 3.0L EFI & DFI Thermostat
The Pro Marine 9004P thermostat is a replacement 130°F marine thermostat for select Mercury and Mariner 175HP-300HP EFI, DFI, OptiMax, Pro Max, and Pro XS outboards.
Designed for high-performance Mercury V6 applications, this thermostat helps maintain proper engine operating temperature for cooling system efficiency, engine protection, and reliable outboard performance.
Compatible Applications
| Horsepower Range | Engine Family | Engine Type | Application Notes |
|---|---|---|---|
| 175HP-200HP | Mercury V6 2.5L | EFI | Select EFI cooling system applications |
| 175HP-200HP | Mercury V6 2.5L | DFI / OptiMax | Select OptiMax thermostat applications |
| 200HP-300HP | Mercury V6 3.0L | EFI | Select EFI cooling systems |
| 200HP-300HP | Mercury V6 3.0L | DFI / OptiMax | Select DFI and OptiMax applications |
| 175HP-300HP | Mercury Pro Max | High Performance V6 | Select Pro Max cooling systems |
| 175HP-300HP | Mercury Pro XS | High Performance V6 | Select Pro XS applications |
| 175HP-300HP | Mariner V6 Outboards | EFI & DFI | Equivalent Mercury platform applications |
We also stock another Pro Marine replacement thermostat for compatible Mercury and Mariner applications.
View Alternate Pro Marine 130°F Thermostat
OEM Part Numbers & Cross References
| Type | Part Number |
|---|---|
| Current Mercury OEM Number | 8M0057307 |
| Mercury Cross Reference | 885599 |
| Mercury Cross Reference | 885599002 |
| Mercury Cross Reference | 885599003 |
| Mercury Cross Reference | 885599004 |
| Mercury Cross Reference | 885599005 |
| Mercury Cross Reference | 8855991 |
| Pro Marine Part Number | 9004P |
What This Thermostat is Used For
This thermostat regulates cooling system water flow to help maintain proper engine operating temperature inside compatible Mercury and Mariner V6 outboards.
Proper thermostat operation is critical for fuel efficiency, combustion quality, cooling system performance, and long-term engine durability.
A sticking or failed thermostat can contribute to overheating, inconsistent engine temperature, poor idle quality, or improper cooling system operation.
Thermostats are commonly replaced during cooling system maintenance, water pump service, or overheating diagnosis on high-performance Mercury outboards.
Key Features and Benefits
- Pro Marine replacement 130°F marine thermostat
- Fits select Mercury and Mariner 175HP-300HP V6 outboards
- Compatible with EFI, DFI, OptiMax, Pro Max, and Pro XS applications
- Replaces Mercury OEM 8M0057307 and 885599 series
- Supports proper engine operating temperature
- Helps maintain cooling system efficiency
- Designed for high-performance marine applications
- Excellent replacement for worn or sticking thermostats
Thermostat Details
- Brand: Pro Marine
- Part Number: 9004P
- Temperature Rating: 130°F
- OEM Reference: 8M0057307
- Cross References: 885599, 885599002, 885599003, 885599004, 885599005, 8855991
- Applications: Mercury & Mariner 175HP-300HP V6 Outboards
- Engine Families: 2.5L & 3.0L V6
- Compatible Systems: EFI, DFI, OptiMax, Pro Max, Pro XS
- System: Cooling System
- Use: Engine temperature regulation
FAQ
What engines does this thermostat fit?
This thermostat fits select Mercury and Mariner 175HP-300HP EFI, DFI, OptiMax, Pro Max, and Pro XS V6 outboards using the listed OEM references.
What temperature is this thermostat?
This is a 130°F marine thermostat.
What OEM numbers does this replace?
This thermostat replaces Mercury OEM number 8M0057307 along with the 885599 series thermostat numbers.
When should a thermostat be replaced?
Thermostats are commonly replaced during cooling system maintenance, overheating diagnosis, or water pump service.
Do you offer another version of this thermostat?
Yes. We also stock alternate Pro Marine thermostat part number 9004 for compatible applications.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on orders over $100 continental U.S.
- Orders ship via UPS, USPS, and FedEx.
- Orders received before 5:30 PM EST ship the same business day.
- Typical delivery time is 1–5 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Cooling system parts should be installed only after proper diagnosis and inspection.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Terms
9004P, 8M0057307, 885599, 885599002, 885599003, 885599004, 885599005, 8855991, Mercury thermostat, Mercury 130 thermostat, Mercury OptiMax thermostat, Mercury Pro XS thermostat, Mercury Pro Max thermostat, Mercury 2.5L thermostat, Mercury 3.0L thermostat, Mercury V6 thermostat, Mariner thermostat, 130 degree marine thermostat, Pro Marine thermostat
8M0057307
885599
885599002
885599003
885599004
885599005
8855991
884408A08
884408T05
884408T06
878231T2
OEM Mercury Thermostat Cover Kit
Mercury 3.0L EFI / DFI / OptiMax Thermostat Cover Assembly
This OEM Mercury thermostat cover kit is designed for select Mercury and Mariner 3.0L EFI, DFI, OptiMax, and Pro XS V6 outboards.
This cover kit helps restore proper thermostat sealing and cooling system performance on compatible Mercury 3.0L high-performance outboards.
Compatible Applications
| Horsepower Range | Engine Family | Engine Type | Application Notes |
|---|---|---|---|
| 200HP-225HP | Mercury / Mariner 3.0L V6 | EFI | Select 3.0L thermostat cover applications |
| 200HP-300HP | Mercury / Mariner 3.0L V6 | DFI / OptiMax | Select 3.0L DFI and OptiMax cooling systems |
| 225HP-300HP | Mercury Pro XS | 3.0L High Performance V6 | Select Pro XS thermostat cover applications |
This thermostat cover kit is commonly serviced together with the thermostat during cooling system maintenance.
View Pro Marine 130°F Thermostat
We also stock the alternate thermostat version:
View Pro Marine 130°F Thermostat 9004P
OEM Part Numbers & Cross References
| Type | Part Number |
|---|---|
| Mercury OEM Number | 885599A1 |
| Mercury OEM Cross Reference | 858856 |
| Pro Marine Item Number | 9004K |
What This Thermostat Cover Kit is Used For
This Mercury thermostat cover kit is used to secure and seal the thermostat assembly inside compatible Mercury 3.0L V6 outboards.
Proper thermostat cover sealing helps maintain correct cooling system pressure, water flow, and engine operating temperature.
Corrosion, damaged sealing surfaces, stripped hardware, or leaking gaskets can contribute to cooling system leaks and temperature regulation problems.
Thermostat cover kits are commonly replaced during thermostat service, cooling system rebuilds, or overheating diagnosis.
Key Features and Benefits
- OEM Mercury thermostat cover kit
- Fits select Mercury and Mariner 3.0L EFI, DFI, and OptiMax outboards
- Compatible with select Mercury Pro XS 3.0L applications
- Replaces Mercury OEM numbers 885599A1 and 858856
- Helps maintain proper thermostat sealing
- Supports proper cooling system operation
- Excellent replacement for corroded or leaking thermostat covers
- Designed for marine outboard cooling systems
Thermostat Cover Kit Details
- Brand: Mercury Marine
- Part Number: 9004K
- OEM References: 885599A1, 858856
- Applications: Mercury & Mariner 3.0L V6 Outboards
- Compatible Systems: EFI, DFI, OptiMax, Pro XS
- Engine Family: 3.0L V6
- System: Cooling System
- Use: Thermostat sealing and cover service
FAQ
What engines does this thermostat cover kit fit?
This kit fits select Mercury and Mariner 3.0L EFI, DFI, OptiMax, and Pro XS V6 outboards using the listed OEM references.
Is this an OEM Mercury part?
Yes. This is an OEM Mercury thermostat cover kit.
What OEM numbers does this replace?
This thermostat cover kit replaces Mercury OEM numbers 885599A1 and 858856.
Should the thermostat also be replaced during service?
In many cases yes. Thermostat covers and thermostats are commonly serviced together during cooling system maintenance.
What happens if the thermostat cover leaks?
A leaking or damaged thermostat cover can contribute to cooling system pressure loss, water leaks, and improper engine temperature regulation.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on orders over $100 continental U.S.
- Orders ship via UPS, USPS, and FedEx.
- Orders received before 5:30 PM EST ship the same business day.
- Typical delivery time is 1–5 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Cooling system parts should be installed only after proper diagnosis and inspection.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Terms
9004K, 885599A1, 858856, Mercury thermostat cover, Mercury thermostat housing, Mercury OptiMax thermostat cover, Mercury Pro XS thermostat cover, Mercury 3.0L thermostat housing, Mercury V6 thermostat cover, Mariner thermostat cover, thermostat cover kit, OEM Mercury thermostat cover kit, Mercury cooling system parts
885599A1
96233A2
96455A15
96455A15
96455A18
96455T18
96220A2
96220A4
96220A7
96220A13
892864T04
8M0174561
892864T04