Which engine was fitted as standard in the Hallberg-Rassy 46, and what problems should I check?

The Hallberg-Rassy 46 normally came with a Volvo Penta TMD31, a four-cylinder, turbocharged marine diesel rated at about 95 hp, driving a conventional propeller shaft. Check the engine identification plate first, then inspect the cooling system, exhaust and turbocharger before a loaded sea trial: age and maintenance history matter more than the hour-meter reading alone.

Confirm the engine specification

The HR 46 was built from the mid-1990s into the mid-2000s, making an original engine several decades old. Advertisements sometimes round the output to 100 hp or omit part of the model designation. Photograph the plate and record the full designation, product number and serial number before ordering parts.

The engine or gearbox may have been replaced. Compare the installation with the original specification and invoices, checking the gearbox identification and reduction ratio too.

• Ask for dated records of oil, filter, coolant and impeller changes, plus evidence of heat-exchanger and exhaust servicing.
• Check whether the hour meter has ever stopped working or been replaced.
• Ask how the boat was winterised and how long it spent unused.
• Look for repeated overheating repairs, unexplained coolant additions or frequent belt replacement.

Four thousand hours is not automatically excessive for a maintained diesel. Long periods standing with salt deposits, damp exhaust components and neglected coolant can do more damage than regular use.

Inspect cooling and wet exhaust

Start with the engine cold. Check the coolant level, seawater strainer, intake hose, hose clips and raw-water pump. Salt tracks or green staining around the pump suggest a leak. Establish whether water has reached nearby bearings or other components.

Remove the impeller cover if the service history is uncertain. Trace any missing blade tips downstream, commonly to the heat-exchanger inlet, before fitting another impeller.

Pay particular attention to the heat exchanger and gearbox oil cooler on an elderly seawater circuit. Ask when they were last opened, cleaned and inspected. External paint can hide corrosion around end caps and hose connections.

Inspect the exhaust mixing elbow, where seawater enters the exhaust, for internal restriction and corrosion. A tidy exterior tells you little about the passages inside. Check the exhaust hose and waterlock for leaks, heat damage and secure support.

Stop the engine and let it cool before opening cooling components. Close the seawater seacock before dismantling the raw-water circuit.