Cylinder Heads

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Introduction

Indeed, when the term “machine” is mentioned different types of machines may come to people’s minds. However for a seafarer when the term “machine” is mentioned it is highly likely that they will think of a diesel engine.

In today’s diesel engines the component that serves as the cylinder’s cover and carries the valves and the seats on which these valves operate is called the “cylinder head”. It can also be referred to as the “cylinder cover” or simply “cover”.

The cylinder head is located at the top of the cylinder in diesel engines. It can be considered as the upper part of the combustion chamber where the piston compresses the air. This is also the area where the issue of “head gasket failure” commonly occurs which is often heard by car owners and those familiar with the industry. The head gasket is located beneath the cylinder head and it can burn out or fail when it reaches the end of its lifespan or is exposed to temperatures higher than its designed operating temperature.

A cylinder cover of MAK Engine

Maintenance

During their career a marine engineer will witness the dismantling and maintenance of the cylinder head or “cover” numerous times. However in most cases more than just ordinary tools are required for the dismantling process. For the removal of the cylinder head hydraulic tools provided by the engine manufacturer are necessary. When the engine is delivered to the ship the manufacturer provides special tools for the ship operator to use. These tools should be utilized for the removal of the cylinder head as well. The answers to questions regarding which tool to use how to set it up and how much pressure to apply can be found in the engine’s instruction book. While it may not take long for a trained eye to find the answers a newly acquainted engineer will need to spend time studying the book to familiarize themselves with the procedures.

The tools is shown as 1 on the drawing is the tools required for the removal of the cylinder head (1)
Dismantling nuts of cylinder heads
Before Dismantling
By using hydraulic tools, the extensions of the studs achieved, allowing the studs to flex in the elastic region. This enables the loosening of the nuts that secure the cylinder head
Cylinder head by 4 strok diesel Wartsila Engines
Cylinder head cleaning in the cleaning machine
After taking out of the cleaning machine fine cleaning is done manually

After cleaning, measurements are taken on the valves of the cylinder head, the valve seats which are the surfaces where the valves operate, and the valve guides that enable the up-and-down movement of the valves along an axis. Parts that out of wear limit are replaced with new spares.

Seat housing can be seen on the picture
Seats assembled
Grinding of valve seats with special Chrs Marine seat grinder
Many diesel engines dissipate excess heat by using cooling water. One of the areas where cooling water circulates is the cylinder head. After maintenance, it is essential to perform a hydro pressure water test to verify that there are no leaks from the water passages.

Mounting

Once all cleaning, inspection, measurement, replacement, and repair procedures are completed the cylinder heads are ready to mount.

Just as hydraulic tools are necessary during the dismantling process, they are also required during the assembly process.
Cylinder Head drawing — Wartsila 32 (1)
 

Sources

(1) — Wartsila 8L32 Instruction Manual

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