Replace or rebuild?

At what point is keeping an old diesel engine throwing good money after bad? PBO expert Stu Davies has some tips to help you decide

- Stu Davies

Most of us will know someone – and may have been that someone ourselves – with a rusty, rattly, oily, or smoking marine diesel engine. The sort of engine that no longer fills us with complete confidence in its reliability.

Many have also been in the position of thinking of buying a second-hand boat with concerns that the engine may be suspect or isn’t performing quite as it should.

First questions

The first thing to do is set a baseline so any decisions or spending of money are based on cold, hard facts.

This entails putting the wallet firmly to one side and rapidly getting an answer to the frank question: ‘is my engine actually shot?’

If that’s the conclusion, the immediate follow-up question is always ‘do I need to buy a new engine or can I refurbish what I currently have?’

These first questions are the most important, and to make an informed decision a definitive survey of the whole engine needs to be performed. At this stage compiling a brief list of pros and cons is a good idea. In approximate order of importance these are:

• Does it start easily?

• Has it been breaking down regularly?