Perkins Perama M-20:
The Compact Legend
The Perkins Perama M-20 auxiliary marine diesel engine is a classic, highly respected propulsion choice for small-to-mid-sized sailing yachts ranging from 25 to 32 feet. Born from a collaboration between Perkins (UK) and Shibaura (Japan), this 3-cylinder powerhouse is renowned for its compact dimensions, low vibration, and mechanical reliability.
Rated Power18 HP
Cylinders3-In-Line
Dry Weight 111 kg
Key Engineering Features
- ◇ Mechanical IDI: Indirect Injection with swirl pre-combustion chamber for efficiency.
- ◇ Closed Cooling: Freshwater loop with a seawater-cooled heat exchanger.
- ◇ Cast Iron Integrity: Heavy-duty block with copper/chrome additives for wear resistance.
Series Displacement (Liters)
Comparing the M-20 (KB/KL) against its larger Perama siblings.
Common Vessel Installations
For years, the M-20 was the standard of excellence for top-tier yacht builders. You will commonly find this engine in:
- Catalina 270 (1991–1995 era)
- Beneteau Oceanis 281 (Primary 18HP install)
- Westerly Marine (Auxiliary standard)
The “Mystery Leak”
Cruisers should be aware of the internal heat exchanger failure. Galvanic corrosion in the AM-420 assembly can cause freshwater to leak into the seawater loop and vanish overboard.
Specialist Tip
“Always carry an 8mm Allen wrench. It’s required for the starter bolts which must be removed to service the heat exchanger.”
Thinking of Repowering?
While the M-20 is a workhorse, modern alternatives like the Yanmar 3YM20 or 3JH40 offer even greater efficiency and lower emissions.
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Perkins M-20 Perama Review | Murray Yacht Sales
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