What engine was fitted as standard in a Nauticat 33, and what are its known weak points?

The standard engine in a Nauticat 33 varies by the year of build, but most left the Finnish factory with a four-cylinder Ford-based marine diesel, typically the 80hp Ford Lehman 2712E or the later 85hp 2722E. These heavy-duty cast-iron blocks are legendary for their half-million-mile lifespans, but their bolt-on marinisation components (specifically the oil coolers and heat exchangers) are their main weak points.

Production eras and engines

Siltala Yachts built over 1,100 Nauticat 33s between 1968 and 1997. This long production run means the standard engine evolved. Buyers will generally find three main eras of factory fitment:

• 1968 to 1981: The 80hp Ford Lehman 2712E was the primary engine. The 72hp Perkins 4.236 was a common factory alternative. Both are slow-revving, naturally aspirated 4-cylinder diesels.
• 1982 to 1989: Production shifted to the newer 85hp Ford 2722E (often badged as a Lehman Super 90).
• 1990 to 1997: Late models usually featured Japanese or Swedish power, typically the 88hp Yanmar 4JH2-DTE or the Volvo Penta TMD31L.

Ford Lehman weak points

The base engine on a Ford Lehman 2712E or 2722E is practically bulletproof. The marinisation parts require strict maintenance. Always isolate the starter battery before putting your hands near the raw water pump or alternator belts.

• Oil coolers: Both the engine oil cooler and the gearbox oil cooler sit in the raw water circuit. The cupronickel tubes corrode over time. A failure pumps high-pressure engine oil into the cooling water or allows seawater into the sump. Replace these every 10 years regardless of hours. New units cost around £150 to £200 each.
• Simms/Minimec injection pump: The inline fuel injection pump on older Fords has its own captive oil reservoir, completely separate from the engine sump. Owners frequently forget to change it. Drain and refill it with about 400ml of standard 15W-40 engine oil every 50 hours. A heavy smell of diesel means the pump seals are failing.
• Raw water pump: The Jabsco raw water pump is gear-driven. The drive tangs wear down, and the internal lip seals eventually leak. Check the weep hole on the underside of the pump body. Dried salt tracks indicate a failed water seal, meaning the bearings will be next.

Perkins 4.236 known issues

The Perkins 4.236 shares the same reliability as the Ford but has a few distinct quirks.