Engines: what can go wrong, and how are they rebuilt?

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If you have ever wondered exactly what happens to your yacht’s engine when it goes in for refit, the video above will show you. As well as feeding your curiosity, we hope it also gives you a better idea of the issues that can occur within an engine.

Remember, you should always stick to the engine manufacturer’s maintenance schedule. This has been calculated on the type of wear expected on various items at certain completed hours/fuel consumption levels. Therefore, to ensure the engine parts remain in good working order for their designed purpose and to try and ensure the correct running of your engine, it is important to never skip recommended inspections or works.

Failure to follow certain maintenance schedules can cost you more money in the long run. The maintenance intervals of other engine parts may get shorter as a result of negligence, meaning larger works are required more frequently. Furthermore, it is dangerous. To completely ignore the schedules for the major works could lead to catastrophic failure, or at best multiple parts needing replacement. Engine failures mid-season don’t tend to please owners and their guests.

0.08 maintenance

Here is the basic engine block ready for rebuild to commence. Ensuring cleanliness is the most crucial step before replacing any parts, as the smallest particle can cause major issues after the works are complete.


0.20 installation

Installation of the piston liners. The most important part of installation is the use of the manufacturer’s special tooling and setting equipment data/procedures to be strictly adhered to.

0.32 installation

Installation of the pistons into the liners, again all thoroughly cleaned prior to installation and using the correct special tooling.

0.53 maintenance

Correctly locating and tightening the lower conrod bearing housing. Final inspections are completed before the final torqueing of the fixings.

01.05 installation

Designed fabricated lifting structure to aid the installation of the cylinder head.

01.06 maintenance

Video endoscopic inspection of the cylinder head’s internal parts prior to installation.

01.54 installation

Final installation of the bare cylinder head to the correct torque sequence and following settings laid out in the CAT workshop manual. It is important that all procedures are followed correctly otherwise again major failure may occur.

02.11 rebuild

Oil pan, exhaust manifold and the rebuild of the top end progresses following the workshop manual instructions.

Final stages of the top end being completed using the correct torques

Final stages of the top end being completed using the correct torques. Parts are continuously referenced direct from the CAT online system.

Installation of the cooling heat exchanger.

Valve settings ongoing alongside the installation of the cooling heat exchanger.

Final installation

Final installation of the electronic and electrical systems.

Final priming

Final priming of the fuel system and inspection of all hoses and connections prior to start up.

A major overhaul has been completed

A major overhaul has been completed to the highest level ending with a sea trial, very proud AJ Marine engineers and of course a very happy customer.

Visit AJ Marine
Visit AJ Marine
L.N.C Engineering
Have an MTU engine? Contact our sister company L.N.C Engineering

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