Diesel Engine Fault Finding

Compared to a modern car’s petrol engine, a boat’s diesel engine is relatively simple. With most diesel engine faults or problems, human interference is probably 80% of the cause, either subconsciously by accident, or caused through some servicing or maintenance of the engine. The recipe for successful fault finding, is the ability to think logically. So before your dive into the engine space with hammers and tools, it’s worth investing a few moments by tracking backwards in time. Ask yourself, was the engine working OK the last time I used it? Has anyone worked on the engine since then? and, did the problem occur suddenly, or did it gradually get worse?

For a fast diagnosis is worth taking a close look at the symptoms and establishing what’s likely as opposed to what’s possible. For example, if the engine’s high temperature alarm goes off, then there’s a list of checks and possible causes the length of ones arm. But, suddenly you may recall running aground on a sand bank the previous day, leading to a strong likelihood that the sea water strainer will be chocked up with sand, as opposed to the unlikely occurrence of having a ground fault on the temperature sensor.

The fault finding routines outlined on this site, are only relevant to the bottom end range of engines. Engines with high tech black box electronics and smart engine management systems - all supposedly marketed for the benefit of better engine performance - are naturally going to throw up a whole range of different complex issues - leaving you very much in the hands of the engine manufacturer or servicing agent. With these black box electronic devices, the simple and quick lamp test and continuity checks that are featured, are no longer possible. Another problem, is that these black boxes can contain engine management software, created with various interlocks, which may prevent the engine from starting until all the engine ancillary services are in working order.