Pro Marine Upper and Lower Crankshaft Oil Seal - 230

The Pro Marine 230 Upper and Lower Crankshaft Oil Seal is an aftermarket replacement designed for select Mercury, Mariner, Johnson, and Evinrude outboard applications. It is cross-referenced to Mercury part number 41953 and numerous additional OEM and aftermarket numbers.

This crankshaft seal is used in compatible two-stroke outboard engines to help maintain proper crankcase sealing around the crankshaft. It is suitable for applicable upper or lower crankshaft sealing locations, depending on the engine configuration.

Mercury application records include select 30-125 HP inline outboards, 135-200 HP V6 engines, 2.5L EFI models, and high-performance engines, along with several Mercury SportJet configurations.

For customers who prefer a factory replacement, Pro Marine USA also carries the Genuine Mercury 41953-OE Crankshaft Oil Seal .

Product Information

• Part Number: 230
• Manufacturer: Pro Marine
• Product Type: Aftermarket Crankshaft Oil Seal
• Seal Application: Upper or Lower Crankshaft, Depending on Engine
• Engine Brands: Mercury, Mariner, Johnson, and Evinrude
• Mercury Outboard Fitment: Select 30-250 HP Engine Families
• Mercury SportJet Fitment: Select 175-240 HP Models
• Primary Mercury Reference: 41953
• Genuine Mercury Alternative: 41953-OE

OEM and Cross Reference Numbers

Pro Marine 230 is listed as an aftermarket replacement associated with the following OEM and aftermarket crankshaft oil seal numbers.

These numbers help identify replacement seals when servicing Mercury, Mariner, Johnson, and Evinrude outboard engines.

Cross-reference numbers are provided for part identification. Verify the original engine application before ordering.

What This Part Is Used For

The Pro Marine 230 crankshaft oil seal helps prevent unwanted air and fluid leakage around the crankshaft in compatible outboard engines.

In a two-stroke outboard engine, maintaining proper crankcase sealing is essential to the engine's operating cycle. The crankcase relies on pressure changes to support the movement of the air-fuel mixture.

A worn or damaged crankshaft seal may allow unwanted air to enter the crankcase, which can contribute to engine performance problems.

Common Applications

• Upper crankshaft oil seal replacement
• Lower crankshaft oil seal replacement
• Two-stroke outboard engine rebuilding
• Powerhead and crankcase repairs
• Crankshaft service and maintenance
• Repair of confirmed crankcase air leaks
• Restoration of older outboard engines

Important Fitment Information

Pro Marine 230 does not fit every Mercury, Mariner, Johnson, or Evinrude outboard engine.

Crankshaft oil seal dimensions and configurations vary between engine families and production ranges. Always confirm the original seal part number, engine model, and serial number.

The following Mercury applications are based on the supplied Mercury parts catalog fitment charts. Johnson and Evinrude compatibility should be verified by OEM part number and engine diagram.

Mercury and Mariner Outboard Fitment

Pro Marine 230 is cross-referenced to crankshaft oil seal applications found throughout multiple Mercury and Mariner outboard engine families.

The following tables summarize the supplied Mercury catalog application records. Fitment is specific to the listed engine models and serial-number ranges.

Mercury 30-60 HP Outboards

Mercury 65-125 HP Outboards

Mercury 135-200 HP V6 Outboards

Compatible catalog applications include select V135, V150, V175, V200, XR4, XR6, Magnum II, Magnum III, Marathon, and EFI engine configurations.

Mercury 2.5L V6 and EFI Outboards

Mercury High-Performance Outboards

Mercury SportJet Engine Fitment

Pro Marine 230 is cross-referenced to crankshaft oil seal applications appearing in Mercury SportJet engine catalog records.

Johnson and Evinrude Outboard Applications

Pro Marine 230 is also associated with crankshaft oil seal replacement searches for Johnson and Evinrude outboard engines.

Johnson and Evinrude cross-reference numbers supplied for this seal include:

• 0313992 / 313992
• 0764337 / 764337
• 0777914 / 777914
• 336232
• 508514
• 775423

When Should a Crankshaft Oil Seal Be Replaced?

Crankshaft seals may become worn or damaged due to age, engine operating conditions, or mechanical problems.

Possible indications of a crankshaft sealing problem include:

• Confirmed crankcase air leakage
• Unstable idle
• Hard starting
• Inconsistent engine performance
• Visible seal damage during disassembly
• Crankshaft seal leakage

These conditions may also be caused by fuel-system, ignition, or other engine problems. Diagnose the source before replacing parts.

Installation and Service Recommendations

• Verify the original crankshaft oil seal part number.
• Confirm engine model and serial-number compatibility.
• Identify the required upper or lower crankshaft sealing location.
• Inspect the crankshaft sealing surface before installation.
• Check for crankshaft or bearing problems that may affect seal life.
• Use the correct seal installation tools and procedures.
• Follow the manufacturer's specified seal orientation.
• Inspect related crankcase seals and gaskets during engine service.
• Perform appropriate engine checks after completing repairs.

Some crankshaft seal replacements require extensive engine disassembly. Follow the applicable service manual or consult a qualified marine technician.

Why Choose Pro Marine 230?

• Aftermarket Replacement: An alternative to the Genuine Mercury crankshaft oil seal.
• Multiple OEM References: Cross-referenced to Mercury 41953 and other listed part numbers.
• Wide Application Coverage: Associated with numerous Mercury outboard and SportJet engine families.
• Crankcase Sealing: Helps maintain proper sealing around the crankshaft.
• Engine Repair Applications: Suitable for compatible powerhead rebuilding and crankshaft seal replacement.
• OEM Option Available: Genuine Mercury 41953-OE is sold separately.
• Wholesale Availability: Qualified marine dealers can access Pro Marine dealer pricing.

Frequently Asked Questions

What is Pro Marine part number 230?

Pro Marine 230 is an aftermarket upper and lower crankshaft oil seal for compatible outboard engines. It is cross-referenced to Mercury 41953 and other OEM and aftermarket seal numbers.

Does Pro Marine 230 replace Mercury 41953?

Yes. Mercury 41953 is a primary cross-reference for Pro Marine 230. Confirm the original engine application before ordering.

What is the difference between Pro Marine 230 and Mercury 41953-OE?

Pro Marine 230 is the aftermarket replacement. Mercury 41953-OE is the genuine Mercury OEM version. Both are available from Pro Marine USA.

Does this seal fit Johnson and Evinrude outboards?

The supplied cross-reference list includes numbers associated with Johnson and Evinrude oil seal searches. Verify the original seal number and engine parts diagram before confirming compatibility.

What Mercury horsepower engines use this seal?

The supplied Mercury catalog application records include select 30-125 HP inline outboards, 135-200 HP V6 engines, and certain high-performance models. Exact compatibility depends on the engine model and serial-number range.

Does Pro Marine 230 fit Mercury SportJet engines?

The supplied application data includes select Mercury SportJet 175, 200, 210, and 240 HP engine families. Verify the required seal location and original part number.

Is this an upper or lower crankshaft oil seal?

Pro Marine 230 is listed for upper and lower crankshaft oil seal applications. The correct location depends on the engine design.

Can a leaking crankshaft seal cause engine performance problems?

Yes. On a two-stroke engine, a crankshaft seal leak can interfere with crankcase pressure and contribute to poor idle, difficult starting, or inconsistent operation.

How do I know if Pro Marine 230 fits my engine?

Locate your engine model and serial number, then verify the original crankshaft oil seal using the manufacturer's parts diagram. Match that part number to the cross-reference list.

Dealer Discounts & Store Policies

Wholesale Marine Parts Pricing

Pro Marine USA supplies aftermarket and genuine OEM marine engine parts to professional marine technicians, repair facilities, boat dealers, and retail customers.

Qualified marine businesses can apply for a Pro Marine dealer account to access wholesale pricing on eligible products.

Apply for Dealer Pricing

Shipping Information

• Free shipping on orders over $100 within the continental United States.
• Orders received before 5:30 PM EST ship the same business day, Monday-Friday.
• Shipping available through UPS, USPS, and FedEx.
• Typical delivery time is 1-5 business days.

Returns

• 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.

Need help identifying the correct crankshaft oil seal? Contact Pro Marine USA or call 941-721-3000.

Searchable Part Numbers

230, 41953, 41953B, 41953-OE, 0313992, 0764337, 0777914, 18-2016, 20079, 25837, 29476, 313992, 336232, 508514, 764337, 775423, 777914, 9-76100

Searchable Terms

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