JOHNSON 338958 Crankshaft Head 40HP

( Manufacturer Part Number: 338958 ), ( Part Type: Crankshaft Head ), ( Country Of Origin: United States )

Review JOHNSON 40hp Crankshaft Head Assembly fits 1994

The **Johnson 338958 1994 40HP Crankshaft Head** is a meticulously engineered, high-performance component designed specifically for the iconic 40 horsepower outboard motor models produced by Johnson in the mid-1990s. Crafted from premium-grade forged aluminum alloy, this crankshaft head is built to withstand the rigorous demands of marine applications, ensuring durability, reliability, and optimal performance under varying load conditions. The design incorporates precision-machined surfaces and balanced weight distribution, which not only enhances the engine s efficiency but also minimizes vibration and wear over extended use. This particular crankshaft head is a critical part of the motor s power train, housing the main bearings and connecting rods that translate the combustion force into smooth, consistent rotational power. Its robust construction and tight tolerances contribute to the engine s ability to deliver consistent horsepower while maintaining operational integrity even in challenging conditions such as rough waters or prolonged operation. Whether used for recreational boating, fishing, or light commercial applications, this crankshaft head exemplifies Johnson s commitment to quality and performance, ensuring that the 1994 40HP outboard motor operates with precision and longevity. For those seeking to restore or upgrade their vintage Johnson outboard, this crankshaft head is an essential replacement part that promises to restore the engine s original power and reliability.

### **Pros and Cons of Buying a Johnson 338958 (1994, 40HP) with a Crankshaft Head**

1. **Reliability and Durability** Johnson outboard motors, particularly older models like the 1994 40HP, are known for their robust construction and longevity when maintained properly. Many of these engines still perform well after decades of use, especially if they have been well-cared-for.

2. **Affordability** Compared to newer outboards, a 1994 Johnson 338958 is significantly cheaper, making it a budget-friendly option for small boats, trolling, or backup power. Parts and labor costs are also lower than for modern engines.

3. **Proven Performance** The 40HP Johnson is a workhorse for its size, capable of handling light fishing, leisure boating, and even some light duty in small boats. It s a reliable choice for those who don t need high horsepower.

4. **Ease of Maintenance** Older Johnson engines are relatively straightforward to service. Many mechanics and DIYers are familiar with their design, and parts are still available through aftermarket suppliers and salvage yards.

5. **Fuel Efficiency** For its size, the 40HP Johnson is fuel-efficient, making it cost-effective for short trips or frequent use in smaller boats.

6. **Resale Value** If well-maintained, a 1994 Johnson 338958 can still fetch a decent price in the used market, especially if it s in good condition.

7. **Simplicity in Operation** The basic design means fewer electronic components to fail, reducing the complexity of troubleshooting compared to modern fuel-injected engines.

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1. **Age and Wear** A 1994 engine is approaching 30 years old, which means it may have accumulated significant wear in critical components like the crankshaft, pistons, and bearings. The fact that you re specifically looking at one with a "crankshaft head" suggests potential internal damage, which could require costly repairs.

2. **Rust and Corrosion** Older engines, especially those stored improperly or used in saltwater, are prone to rust and corrosion. This can lead to leaks, seized components, or reduced performance.

3. **Emissions and Environmental Concerns** This engine predates modern emissions regulations, meaning it likely lacks catalytic converters, PCVs, or other pollution-control features. Operating it in areas with strict emissions laws (e.g., some lakes or marinas) may be restricted or prohibited.

- Electronic fuel injection (it likely uses carburetors, which are less efficient and more prone to clogging).

- Digital diagnostics or easy-to-read gauges.

- Modern materials (e.g., aluminum instead of cast iron in some parts, which can wear faster).

- Quiet operation or vibration dampening.

5. **Part Availability** While parts are still available, some may be harder to find than for newer models. OEM (Original Equipment Manufacturer) parts may be discontinued, requiring aftermarket or salvaged alternatives.

6. **Fuel and Oil Compatibility** Older engines often require specific fuel blends (e.g., leaded fuel if not converted) and older-style oil. Modern fuels and additives may not be compatible, leading to performance issues or damage.

7. **Resale Depreciation** Unlike newer engines that hold value, an older Johnson will depreciate further over time. If you plan to sell it later, the return on investment may be minimal.

- Worn or cracked crankshaft bearings.

- Scored or damaged cylinder walls.

- Blown head gaskets or cracked cylinder heads.

- Rod or connecting rod wear.

These issues can be expensive to repair, sometimes costing more than the engine is worth.

9. **No Warranty or Support** Johnson outboards are no longer manufactured, so there s no warranty or authorized service support. Any repairs will be at your own expense.

10. **Safety Concerns** Older engines may lack modern safety features like automatic kill switches, improved ignition systems, or better cooling systems, increasing the risk of mechanical failure while on the water.

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Buying a 1994 Johnson 338958 40HP with a crankshaft head issue is a high-risk, low-reward proposition. The engine s age and the specific problem you ve identified (crankshaft head) strongly suggest that it may require significant repairs or replacement of critical components. While the upfront cost is low, the potential for hidden mechanical failures, high repair costs, and limited resale value make this a poor investment for most buyers.

If you re looking for a reliable, low-cost outboard for occasional use in a small boat, a well-maintained older Johnson *without* major internal issues could be a viable option provided you re prepared for the maintenance and potential for future problems. However, if the crankshaft is damaged, the cost to restore it to good working order may exceed the engine s value.

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- Compression test to check cylinder condition.

- Crankshaft and bearing inspection.

- Cooling system check for leaks or corrosion.

- Carburetor or fuel system cleaning.

This will give you an accurate assessment of the engine s condition and repair costs.

2. **Consider a Replacement Engine** If the crankshaft is beyond repair, weigh the cost of restoring this engine against buying a used or refurbished outboard of similar horsepower (e.g., a Yamaha 40HP, Mercury 40HP, or even a newer Johnson model if available). A modern or well-maintained used engine may offer better reliability and lower long-term costs.

- A backup engine for a boat where the primary motor is reliable.

- A trolling motor or small fishing boat where high performance isn t critical.

- A project boat where you re okay with potential downtime for repairs.

4. **Budget for Repairs** If you purchase it with the intention of fixing it, set aside at least **$500 $1,500** for labor and parts, depending on the extent of the damage. This engine may not be worth fixing if the repair cost approaches or exceeds the value of a new used outboard.

- A **used 2-stroke outboard** (e.g., Yamaha 40HP, Mercury 40HP) with a known service history.

- A **4-stroke outboard** (e.g., Yamaha 40HP 4-stroke) for better fuel efficiency and lower maintenance.

- A **salvaged or rebuilt engine** from a reputable dealer, which may come with warranties.

6. **Avoid Saltwater Use** If you plan to use it in saltwater, be prepared for accelerated corrosion and higher maintenance costs. Freshwater use is generally safer for older engines.

In summary, unless you re a mechanic with the time and skills to restore this engine to good condition, the risks outweigh the benefits. A more modern or well-maintained used outboard is likely a smarter long-term investment.

Details:

Condition: Preowned. PART NUMBER: 338958. Contact a dealer to verify this is the correct part fit your machine.: 1994 Johnson 40HP Crankshaft Head Assembly 0435702 338958.

You get what you see in the pictures so please look closely at all of pictures, for wear and tear to make sure that this is exactly want before decide purchase.

part #: 338958 prices

• $15.00-$90.00

specifications ouboaen:

• for makes: Johnson
• for years: 1994
• mpn: 338958
• part type: Crankshaft Head
• country of origin: United States

general ouboaen:

• Boat Parts > Outboard Engines Components > Other
• condition: Used

returns ouboaen:

• paid by: Buyer
• time: 30 Days
• policy: Returns Accepted

offer ouboaen:

• options: Ship-to-home
• best offers: True
• sold: 0
• quantity: 1
• availability: In Stock
• started: March 25, 2026

seller ouboaen:

• city: Lake City, Michigan
• # reviews: 2656
• rating: 99.6%

payments ouboaen:

• credit card: Mastercard
• cash
• wallet: Google-pay
• other

shipping ouboaen:

• type: Fixed
• class: Standard
• transit: 3-8 Days
• service: USPS First Class
• cost: $0.00
• carrier: USPS

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