Yanmar 3YM20 Impeller 128990-42570 Inspection Guide
August 26, 2026
- Yanmar 3YM20 Impeller Kit 128990-42570 Inspection Guide
- Yanmar Marine Engine Parts
- Yanmar 3YM20 Impeller Part Number
- What Should You Check on a Yanmar 3YM20 Impeller?
- Don't Just Replace a Damaged Impeller
- Missing Impeller Vanes? Account for the Missing Material
- Why Missing Impeller Pieces Can Matter
- Install the 3YM20 Impeller in the Correct Direction
- Inspect the Wear Plate and Pump Interior
- Why Seawater Impellers Become Damaged
- Insufficient Seawater Supply
- Dry Running
- Debris
- Age and Service
- Extended Inactivity
- Yanmar 3YM20 Running Hot? Check the Complete Seawater Supply
- 1. Seawater Intake
- 2. Seawater Strainer
- 3. Seawater Pump
- 4. Wear Plate
- 5. Hoses and Connections
- 6. Downstream Cooling Circuit
- 7. Continue Diagnosis
- Still Overheating After Installing a New Impeller?
- Keep the Removed Impeller for Inspection
- Ordering Yanmar 3YM20 Impeller Kit 128990-42570
- request@alfamarinespareparts.com
- Request a Quote
- Frequently Asked Questions
- What is the impeller kit part number for a Yanmar 3YM20?
- Is Yanmar 128990-42570 an impeller kit?
- What damage should I look for on a Yanmar 3YM20 impeller?
- Does impeller installation direction matter?
- What should I do if part of the old impeller is missing?
- Can a damaged impeller cause a Yanmar 3YM20 to overheat?
- Why is my 3YM20 still running hot after changing the impeller?
- Should the seawater pump be inspected when changing the impeller?
- What information should I provide when ordering Yanmar 3YM20 parts?
- Conclusion