Second-hand marine diesel engines for boats

Is it a good idea to buy second-hand marine diesel engines?

Second-hand marine diesel engines for boats are a very popular option among shipowners, fishermen and leisure boat owners who want to reduce costs without giving up reliability. With proper maintenance and a prior professional inspection, a used engine can deliver excellent performance for many years.

In this article, we explain what you should take into account and how to choose a second-hand marine diesel engine with guarantees.

Advantages of buying second-hand marine diesel engines

Choosing second-hand marine diesel engines for boats has clear benefits:

1. Much lower price

A new engine can require a very high investment. Choosing a second-hand marine diesel engine can save up to 40–70% compared to the original price.

2. Immediate availability

The market for second-hand marine diesel engines usually offers units ready for installation, avoiding long delivery times associated with new engines.

3. Excellent durability

Marine diesel engines are designed to withstand thousands of operating hours. If they come from an owner who has carried out regular maintenance, they remain extremely reliable engines.

4. Discontinued engine models

In the case of discontinued marine diesel engines, the second-hand market becomes a key advantage, as these engines are no longer manufactured and this is the only way to acquire them. Many of these engines are still highly valued for their reliability and mechanical simplicity, allowing existing installations to be replaced or maintained without costly modifications.

Disadvantages of buying a second-hand diesel engine

1. Unknown usage history, which may hide poor maintenance or intensive use.
2. Invisible internal wear, especially in critical components such as pistons, liners, bearings or the injection system.
3. Risk of internal corrosion caused by prolonged exposure to the marine environment and salinity.
4. Cooling system issues, such as heat exchangers, pumps or ducts blocked by deposits.
5. Limited availability of spare parts for older or discontinued engines, which can increase repair costs.
6. Need for additional adjustments or repairs after installation, increasing the final purchase cost.
7. Lack of warranty if the engine does not come from a specialised supplier or has not been bench-tested.

What to check before buying a second-hand marine diesel engine

• Not all used engines offer the same guarantees. We recommend paying attention to:
• Actual operating hours – the equivalent of mileage in a car.
• Overall condition of the engine block – signs of corrosion, leaks or improvised repairs.
• Cylinder compression – correct readings indicate good internal health.
• Maintenance history – oil, filters, inspections and replaced parts.
• Condition of the cooling system – pumps, heat exchangers and seawater/freshwater circuits.
• Engine sound when cold and hot – knocking, smoke or vibrations can be warning signs.

Where to buy second-hand marine diesel engines

Purchasing a used engine should always be done through a specialised technical service or distributor to avoid risks.

At Talleres Nasio, we inspect, test and certify used marine engines to guarantee their correct operation. We also offer bench testing, detailed technical reports, full servicing and installation if required.

Buying a properly inspected second-hand marine diesel engine is a highly recommended option when carried out with professional inspection and a trusted supplier.