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Home > Outboard > Mercury Outboard

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

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.

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Fuel Supply Module

Mercury 75-150HP Mercruiser 4.5L Alpha MPI

Item#:

68585

Cross Reference#:

8M0057676
8M0057676
8M0121387
8M0121387
8M0132733
8M0132733
8M0158586
8M0235171

Manufacturer Item:

8M0158586

Manufacturer:

Mercury Marine

Available:

In Stock

Your Price:

1069.99

Each

Qty:

Pinion Nut Washer

Mercury 135-300hp Force 90-150 Verado L4&6 MC Alpha I & GenII

Item#:

92721

Cross Reference#:

F694186
F694186
18-2343-9
18-2359
32800
346546
350038
9-78108
92721

Manufacturer Item:

92721

Manufacturer:

Engineered Marine Parts

Available:

In Stock

Your Price:

1.24

Each

Qty:

Yamaha F75-F115 Intake Valve Stem Seal Pro Marine A3721

Aftermarket Intake Valve Seal | Replaces Yamaha K0A-A3721-00-00

Pro Marine Aftermarket Intake Valve Stem Seal

Yamaha F75-F115 Intake Valve Stem Seal - Pro Marine A3721

The Pro Marine A3721 Intake Valve Stem Seal is an aftermarket replacement for select Yamaha four-stroke outboard cylinder heads using Yamaha OEM K0A-A3721-00-00.

Verified applications include select F75, F80, F90, F100, F115 and LF115 Yamaha four-stroke engines.

Pro Marine also stocks the genuine Yamaha OEM version, plus the matching exhaust valve seals, valve spring, intake valve and exhaust valve used during cylinder-head rebuilding.

Aftermarket Replacement for Yamaha OEM

Pro Marine: A3721
Yamaha OEM: K0A-A3721-00-00
Application: Intake Valve Stem Seal

OEM & Cross Reference Numbers

Brand / Type	Part Number
Pro Marine	A3721
Yamaha OEM	K0A-A3721-00-00

Yamaha Outboard Fitment

Engine Family	Verified Applications
F75	F75TLRB - 2003 F75TLRC - 2004 F75TLRD - 2005 F75LA / F75LA_0112 - 2006-Present F75TLR / F75TLR_041 - 2006-Present
F80	F80TLRX / F80TXRX - 1999 F80TLRY / F80TXRY - 2000 F80TLRZ - 2001 F80TJRA / F80TLRA - 2002 F80TJRB / F80TLRB - 2003
F90	F90TJRB / F90TLRB - 2003 F90TJRC / F90TLRC - 2004 F90TJRD / F90TLRD / F90TXRD - 2005 F90JA / F90JA_0112 - 2006-Present F90LA / F90LA_0112 - 2006-Present F90TJR / F90TJR_041 - 2006-Present F90TLR / F90TLR_041 - 2006-Present F90TXR / F90TXR_041 - 2006-Present F90XA / F90XA_0112 - 2006-Present
F100	F100TLRX / F100TXRX - 1999 F100TLRY / F100TXRY - 2000 F100TLRZ / F100TXRZ - 2001 F100TLRA / F100TXRA - 2002 F100TLRB / F100TXRB - 2003
F115 - 2000-2005	F115TLRY / F115TXRY - 2000 F115TLRZ / F115TXRZ - 2001 F115TJRA / F115TLRA / F115TXRA - 2002 F115TJRB / F115TLRB / F115TXRB - 2003 F115TJRC / F115TLRC / F115TXRC - 2004 F115TJRD / F115TLRD / F115TXRD - 2005
F115 - Later Models	F115JA, F115LA, F115TJR, F115TLR, F115TXR and F115XA applications from 2006-Present, including supplied 011, 061, 04 and 0405-0411 suffix variants.
LF115	LF115TXRY - 2000 LF115TXRZ - 2001 LF115TXRA - 2002 LF115TXRB - 2003 LF115TXRC - 2004 LF115TXRD - 2005 LF115TXR / LF115TXR_0 / 0405-0407 - 2006-Present LF115XA / LF115XA_01 / LF115XA_06 - 2006-Present

Fitment Note

Verify the complete Yamaha model number before ordering. Yamaha used different cylinder-head and valve-train components across similar horsepower families.

Confirm that the engine application calls for K0A-A3721-00-00.

Genuine Yamaha OEM Option

Yamaha OEM Intake Valve Stem Seal - K0A-A3721-00-00

Prefer genuine Yamaha? Pro Marine also stocks the OEM intake valve stem seal for the same compatible applications.

Brand: Yamaha OEM
OEM Number: K0A-A3721-00-00

View Yamaha OEM Intake Valve Seal

Related Cylinder Head Rebuild Parts

Pro Marine Valve Spring - 67F-12114P

Replacement valve spring for compatible Yamaha F75-F115 four-stroke cylinder heads.

OEM: 67F-12114-00-00

View Valve Spring

Yamaha OEM Exhaust Valve Stem Seal

Genuine Yamaha OEM exhaust-side valve stem seal for compatible four-stroke cylinder heads.

Brand: Yamaha OEM

View OEM Exhaust Valve Seal

Pro Marine Exhaust Valve Stem Seal - A3722

Aftermarket exhaust valve stem seal for compatible Yamaha four-stroke engines.

Brand: Pro Marine

View Pro Marine Exhaust Seal

Pro Marine Intake Valve - 68V-12111P

Length: 96.9mm
Head Diameter: 29mm

Replacement intake valve for compatible Yamaha four-stroke cylinder-head rebuilds.

View Intake Valve

Pro Marine Exhaust Valve - 68V-12121P

Length: 99.3mm
Head Diameter: 23.9mm

Replacement exhaust valve for compatible Yamaha four-stroke cylinder-head rebuilds.

View Exhaust Valve

Valve Train Service Components

Component	OEM / Aftermarket Option
Intake Valve Stem Seal	Pro Marine A3721 / Yamaha OEM K0A-A3721-00-00
Exhaust Valve Stem Seal	Pro Marine A3722 / Yamaha OEM K0A-A3722
Valve Spring	Pro Marine 67F-12114P
Intake Valve	Pro Marine 68V-12111P
Exhaust Valve	Pro Marine 68V-12121P

What This Part is Used For

The intake valve stem seal fits around the intake valve stem and helps regulate the amount of engine oil that passes between the valve stem and valve guide.

The valve guide requires lubrication, but excessive oil entering past the guide can reach the intake port and combustion chamber. The valve stem seal helps control this oil flow while allowing the valve to move normally.

Why Intake Valve Stem Seals Matter

Valve stem seals operate in a high-temperature environment and can become hardened, worn or damaged over time. A deteriorated seal may allow excess oil into the combustion chamber.

During a cylinder-head rebuild, replacing valve stem seals while the valves are already removed can prevent having to disassemble the valve train again later.

When to Replace Valve Stem Seals

During a complete cylinder-head rebuild
When replacing intake or exhaust valves
When servicing valve guides
If seals are hardened, cracked, flattened or damaged
When excessive oil usage is traced to the cylinder head
After overheating or cylinder-head damage
During a complete powerhead overhaul

Inspect These Components at the Same Time

Intake valves
Exhaust valves
Exhaust valve stem seals
Valve guides
Valve seats
Valve springs
Spring retainers and keepers
Camshaft lobes and journals
Cylinder-head sealing surfaces

Shop Yamaha Engine Rebuild Parts by Model

Pro Marine stocks pistons, piston rings, main bearings, rod bearings, cylinder sleeves, valves, valve seals, gaskets and other internal Yamaha four-stroke engine components.

Shop Yamaha Engine Rebuild Parts by Model

Key Features

Pro Marine aftermarket intake valve stem seal
Pro Marine part number A3721
Replaces Yamaha K0A-A3721-00-00
Fits select Yamaha F75 four-stroke applications
Fits select Yamaha F80 four-stroke applications
Fits select Yamaha F90 four-stroke applications
Fits select Yamaha F100 four-stroke applications
Fits extensive Yamaha F115 applications
Fits Yamaha LF115 applications
Genuine Yamaha OEM intake seal available as an alternative
OEM and Pro Marine exhaust valve seals linked above
Valve spring linked above
Pro Marine intake and exhaust valves linked above

FAQ

What Yamaha OEM number does Pro Marine A3721 replace?
A3721 replaces Yamaha K0A-A3721-00-00.

Is A3721 a Yamaha OEM part?
No. A3721 is the Pro Marine aftermarket version.

Can I buy the Yamaha OEM version instead?
Yes. The genuine Yamaha K0A-A3721-00-00 intake valve stem seal is linked above.

Does A3721 fit Yamaha F115?
Yes. The supplied fitment includes extensive F115 applications from early engines through later models.

Does this fit Yamaha F75, F80, F90 and F100?
Yes. Select models from each of those engine families are included in the verified fitment above.

Does A3721 fit Yamaha LF115?
Yes. Multiple LF115 applications are included.

Do you stock the exhaust valve stem seal?
Yes. Both Yamaha OEM K0A-A3722 and Pro Marine A3722 exhaust valve stem seals are linked above.

Do you stock the intake and exhaust valves?
Yes. Pro Marine 68V-12111P intake and 68V-12121P exhaust valves are linked above.

Do you stock the valve spring?
Yes. The Pro Marine 67F-12114P valve spring is linked above.

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.

Apply for a Dealer Account

Shipping Policy

Free shipping on orders over $100 in the continental U.S.
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.
Parts must be new, unused and in original packaging.
Installed parts are not returnable.
Return authorization is required before returning parts.

Need help verifying fitment?
Contact Pro Marine
Phone: 941-721-3000

Searchable Part Numbers & Terms

A3721, Pro Marine A3721, K0A-A3721-00-00, K0AA37210000, K0A-A3721, Yamaha intake valve seal, Yamaha intake valve stem seal, aftermarket Yamaha valve seal, Yamaha F75 valve seal, Yamaha F80 valve seal, Yamaha F90 valve seal, Yamaha F100 valve seal, Yamaha F115 valve seal, Yamaha LF115 valve seal, F115 intake valve seal, F115 valve stem seal, K0A-A3722, A3722, Yamaha exhaust valve seal, 67F-12114P, 67F-12114-00-00, Yamaha valve spring, 68V-12111P, Yamaha intake valve, 68V-12121P, Yamaha exhaust valve, Yamaha F115 cylinder head rebuild, Yamaha valve train parts, Yamaha engine rebuild parts

Item#:

K0A-A3721

Cross Reference#:

K0A-A3721-00-00

Manufacturer Item:

K0A-A3721-00-00

Manufacturer:

Yamaha Outboard

Available:

In Stock

Your Price:

6.99

Each

Qty:

Yamaha F75-F115 Exhaust Valve Stem Seal OEM K0A-A3722-00-00

Genuine Yamaha Exhaust Valve Seal for F75 F80 F90 F100 F115

Genuine Yamaha OEM Exhaust Valve Stem Seal

Yamaha F75-F115 Exhaust Valve Stem Seal - OEM K0A-A3722-00-00

The Yamaha K0A-A3722-00-00 Exhaust Valve Stem Seal is a genuine OEM replacement seal for select Yamaha four-stroke outboard cylinder heads.

Verified applications include select F75, F80, F90, F100, F115 and LF115 Yamaha four-stroke engines.

Pro Marine also stocks the A3722 aftermarket exhaust valve seal, along with the matching intake valve seals, valve spring, intake valve and exhaust valve used during cylinder-head rebuilding.

Genuine Yamaha OEM Exhaust Valve Seal

OEM Number: K0A-A3722-00-00
Application: Exhaust Valve Stem
Engine Families: Yamaha F75-F115 and LF115