TOHATSU Outboard Crankcase Cylinder Set Ring 25HP 30HP 40HP 353-63723-1

( Brand: Tohatsu ), ( Manufacturer Part Number: 353637231 ), ( Part Type: Ring Cylinder ), ( Warranty: 30 Day ), ( Country Of Origin: Japan )

Review TOHATSU Nissan Outboard 25hp 30hp 40hp Crankcase Cylinder Set Ring

The **Tohatsu 353637231 Crankcase Cylinder Set with Rings (Part Number 353-63723-1)** is a high-performance, precision-engineered replacement component designed exclusively for select **Nissan outboard motors**, including models equipped with **25hp, 30hp, and 40hp** two-stroke and four-stroke engines. This meticulously crafted assembly is engineered to restore optimal engine efficiency, power output, and longevity, ensuring seamless operation for both recreational and professional boating applications. The crankcase cylinder set is constructed from **high-grade aluminum alloy**, carefully machined to meet OEM specifications, which guarantees a perfect fit and minimal clearance for improved compression and fuel economy. The included **compression rings** are forged from durable, heat-resistant materials, designed to maintain a tight seal within the cylinder bore, reducing blow-by and preventing premature wear on critical engine components. Whether replacing a worn cylinder due to corrosion, mechanical damage, or routine maintenance, this set provides a reliable, long-lasting solution that helps maintain the engine s original performance characteristics. Ideal for marine technicians and DIY enthusiasts, this part is a critical upgrade for engines experiencing reduced power, excessive oil consumption, or unusual noise, ensuring a smooth, trouble-free operation for years to come.

### **Pros and Cons of buying a Tohatsu 353637231 (Nissan Outboard) Crankcase Cylinder Set with Rings (Part #353-63723-1)**

This part is designed for **Tohatsu 25HP, 30HP, and 40HP outboards** (specifically models with the **353-series engine**) and includes a **crankcase, cylinder, and piston rings**. Below is a detailed breakdown of its advantages and drawbacks.

---

### **Pros**

1. **Direct OEM Replacement**

- The part is manufactured to **exact OEM specifications**, ensuring proper fit and function with minimal modifications. This reduces the risk of compatibility issues compared to aftermarket knockoffs.

2. **High-Quality Materials**

- Tohatsu and Nissan outboards are known for **durable, corrosion-resistant components**, and this crankcase set follows those standards. The cylinder is typically made from **cast aluminum or iron**, while the piston rings are designed for **sealing efficiency** and longevity.

3. **Improved Engine Performance**

- A **fresh crankcase and cylinder** can restore **compression and power output**, especially if the original components were worn or damaged. This is particularly useful for **high-mileage or heavily used outboards**.

4. **Prevents Long-Term Damage**

- If the crankcase or cylinder is cracked, warped, or scored, replacing it early can **prevent catastrophic engine failure** (e.g., seized pistons, oil leaks, or loss of compression). This is a **preventive maintenance** upgrade rather than a last-resort fix.

5. **Compatibility with Common Models**

- The **353-63723-1** part number covers **25HP, 30HP, and 40HP Tohatsu/Nissan outboards** (e.g., **Tohatsu MF25, MF30, MF40, and similar Nissan models**). This makes it a **versatile upgrade** for older boats.

6. **Easier Installation Than Full Engine Replacement**

- Replacing just the **crankcase and cylinder** is **less labor-intensive** than swapping an entire engine. This reduces **labor costs** and **downtime** compared to a full engine overhaul.

7. **Potential for Increased Resale Value**

- If the outboard is being prepared for **sale or trade-in**, a **restored crankcase and cylinder** can make the engine appear **more reliable**, potentially increasing its perceived value.

8. **Warranty Coverage (If Purchased New)**

- If buying from an **authorized dealer or manufacturer**, the part may come with a **limited warranty**, providing peace of mind against defects.

---

### **Cons**

1. **High Upfront Cost**

- Replacement crankcase and cylinder sets are **expensive** typically **$300 $800 **, depending on the model and retailer. This is a **significant investment** compared to minor repairs (e.g., piston rings alone).

2. **Requires Professional Installation (Unless Skilled)**

- While the part itself is straightforward, **removing the old crankcase, sealing the new one properly, and ensuring correct piston ring installation** requires **mechanical expertise**. DIYers may struggle with:

- **Gasket sealing** (poor sealing can cause oil leaks).

- **Cylinder alignment** (misalignment can lead to premature wear).

- **Torque specifications** (over/under-tightening can damage threads or bearings).

3. **Labor-Intensive Replacement Process**

- **Disassembling the lower unit and engine components.**

- **Removing old gaskets, seals, and potentially the crankshaft (if needed).**

- **Cleaning and inspecting mating surfaces.**

- **Installing the new crankcase, cylinder, and rings.**

- **Reassembling and breaking in the engine properly.**

- This can take **4 8 hours** for a professional mechanic, adding to costs.

4. **Potential for Hidden Damage**

- If the **crankshaft, bearings, or rod bearings** are already worn, replacing just the crankcase won t fix those issues. A **full engine inspection** may be needed, increasing expenses.

5. **Break-In Period Required**

- A new cylinder and rings need a **proper break-in** (avoiding high RPMs, using fresh oil, and following manufacturer guidelines) to prevent **scoring or excessive wear**. Skipping this can **void warranties** and reduce longevity.

6. **Limited Availability of Parts**

- While Tohatsu/Nissan parts are widely available, **older models (pre-2010)** may have **discontinued part numbers**, making sourcing difficult. Always verify **compatibility** before purchasing.

7. **Risk of Counterfeit Parts**

- Some sellers (especially online) may offer **fake or low-quality replicas**. Buying from **authorized dealers or reputable marine suppliers** (e.g., **MarineMax, West Marine, or Tohatsu/Nissan service centers**) reduces this risk.

8. **Opportunity Cost of Downtime**

- If the boat is **not in use during repairs**, the owner loses **rental income, fishing trips, or recreational time**, which can be a **financial and personal inconvenience**.

---

### **Conclusion**

Replacing the **Tohatsu 353637231 crankcase and cylinder set** is a **cost-effective way to restore engine health** if the original components are failing. It is **more economical than a full engine replacement** but **requires careful planning and professional installation** to avoid costly mistakes.

**Older outboards (10 years) showing signs of wear** (oil leaks, loss of power, rough idle).

**Boats used frequently in rough conditions** (saltwater corrosion accelerates cylinder wear).

**Owners planning to keep the boat long-term** (restoring reliability vs. replacing the engine).

**Preventative maintenance** before a major failure occurs.

**Boats with severe internal damage** (cracked crankshaft, worn bearings) that require a full engine rebuild.

**Casual users who rarely operate the boat** (cost may not justify the benefit).

**Those without access to a mechanic** (DIY risk is high for inexperienced users).

---

### **Recommendation**

1. **Verify Compatibility**

- Double-check that the **353-63723-1** part number matches your **exact outboard model** (consult the **engine serial number** or service manual).

2. **Get a Professional Inspection First**

- Before purchasing, have a **marine mechanic inspect the engine** to confirm that only the crankcase/cylinder needs replacement (not the crankshaft, bearings, or lower unit).

3. **Buy from an Authorized Source**

- Purchase from **Tohatsu/Nissan dealers, MarineMax, or West Marine** to ensure **genuine, high-quality parts** and warranty coverage.

4. **Plan for Professional Installation**

- Unless you have **mechanical experience**, **hire a certified marine technician** to avoid installation errors. The cost of labor is a **necessary investment** to ensure longevity.

5. **Follow Break-In Procedures**

- After installation, **follow the manufacturer s break-in guidelines** (e.g., **avoid high RPMs for the first 20 hours**, use **synthetic oil**, and monitor for leaks).

6. **Consider a Full Engine Rebuild if Needed**

- If the inspection reveals **additional internal damage**, weigh the cost of a **partial rebuild (crankcase cylinder)** vs. a **full engine overhaul or replacement**.

7. **Budget for Additional Costs**

- **Labor costs** (typically **$300 $600** for installation).

- **New gaskets, seals, and oil** (if required).

- **Potential follow-up repairs** if hidden damage is found.

### **Final Verdict**

- The engine is **showing clear signs of cylinder wear** (low compression, oil consumption, rough running).

- The boat is **used regularly and needs long-term reliability**.

- You **have access to professional installation**.

- The engine has **other major issues** (cracked crankshaft, seized bearings).

- The boat is **rarely used** and the cost doesn t justify the benefit.

- You **lack the mechanical skills or tools** for proper installation.

If the budget is tight, consider **only replacing the cylinder and rings** (if the crankcase is still intact) or **rebuilding the lower unit** before committing to a full crankcase swap. However, if the **crankcase is cracked or warped**, replacement is the **most cost-effective long-term solution**.

Details:

This used setting ring is in excellent functional condition. Please verify your engine intake configuration and part number before purchasing. Please compare your original intake flange to the configuration shown in photos before purchasing. The registration surfaces remain completely true and smooth, ensuring a flawless slip-fit alignment without loose play or mechanical binding.

Color: Natural Metallic. Material: Precision-Machined Marine-Spec High-Tensile Alloy. Function: Acts as a critical precision alignment guide index pin between the power head split lines of crankcase blocks and cylinders. Tohatsu Nissan 2-Stroke Outboard model's 40HP M40C and NS40C series: All Years.

Condition: Used / Inspected Bench Verified. Note: This locating collar is engineered across multiple multi-cylinder block configurations. This is an original genuine Tohatsu / Nissan Outboard Cylinder and Crankcase Set Ring alignment collar Part #353-63723-1 353637231. Tohatsu Nissan 4-Stroke Outboard model's 25HP MFS25B and NFS25B series: Select Years.

FITMENT: Based on verified factory marine parts microfiche data, this crankcase alignment set ring fits an extensive range of Japanese-built Tohatsu and Nissan Outboard 2-Stroke 4-Stroke configurations produced from 1986 Later, including: model's 25HP 30HP M25C, M25C2, M25C3, M30A, M30A2, M30A3, M30A4 series: All Years.

part #: 353637231 prices

• $8.00-$14.99

specifications ouboaen:

• for makes: Nissan
• brand: Tohatsu
• mpn: 353637231
• part type: Ring Cylinder
• warranty: 30 Day
• country of origin: Japan

payments ouboaen:

• other
• credit card: Diners-club
• wallet: Apple-pay

seller ouboaen:

• # reviews: 13021
• city: Munising, Michigan
• rating: 99.8%

offer ouboaen:

• availability: In Stock
• started: May 21, 2026
• options: Ship-to-home
• quantity: 1
• best offers: True
• sold: 0

shipping ouboaen:

• transit: 2-7 Days
• type: Fixed
• cost: $0.00
• service: Expedited
• class: Expedited

general ouboaen:

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

returns ouboaen:

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

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