WHEN AND WHY SHOULD MARINE ENGINE MOUNTS BE REPLACED?

The main goal of the marine engine mounts is to isolate the vibration generated by the engine and to absorb shocks / vibration when the vessel is cruising.

The elastic properties of the marine engine mounts are essential to the prevention of engine damage and to improve the comfort of the boat’s passengers.

Must these products be replaced? How do we know when they need to be replaced? What features should they have to assure a long period of durability?

We will answer these questions on this article.

What are the risks of not replacing flexible engine mounts?

Being an essential part of the vessel, worn engine mounts can cause damage to the engine, twist the propulsion shaft, cause vibrations and unwanted noise which is annoying to passengers. In extreme cases it can represent a flotation hazard if the engine is not properly fixed in place.

How long do the marine engine mounts last?

If we follow the manual of several marine engine manufacturers, engine mounts must be replaced every 1000h or every 4 years. Ellebogen engine mounts provide full functionality for at least 5-7 years depending on the sailing style and engine. We recommend checking them regularly during the season maintenance.

Can the replacement of the marine engine mounts be done by yourself?

There is no need to be a professional mechanic, you can replace mounts yourself. Although you must follow a series of steps and have the right tools for the job. There is a community of users of Ellebogen marine engine mounts, who share their experiences and processes used to change the engine mounts. The following video shows the method of replacing the engine mounts. There are also several case studies on the following  BLOG

When do I have to replace the marine engine mounts?

There are several signs that indicate that the engine mounts are worn out. Below, we list a series of symptoms that will allow us to recognize when a marine engine mount need to be replaced.

1. INCREASED VIBRATIONS

If you start the marine engine and notice that it is making more noise than usual or you feel more vibrations than usual, this is an unmistakable sign that a marine engine mount is worn out and need to be replaced. If a mount is damaged, its antivibration properties are reduced.

An increase in vibrations leads to more engine noise than usual, which can be extremely harmful if allowed to continue over a long period of time. The following video shows some engine mounts with this problem.

2. EXCESSIVE MOVEMENT ON IGNITION OR ON STOPPING THE ENGINE

If when starting engine you notice excessive movement, giving you the feeling that something is not quite right. This is another sign that a marine engine mount is worn out or damaged. This situation may seem to stabilize at times, but if left unchecked the problem will eventually reappear.

 In the following video we can see a engine mounts in action in slow motion

3. EXCESSIVE MOVEMENT OF THE ENGINE WHILE SAILING/CRUISING

Often, a marine engine mount that needs to be replaced might move excessively in rough sailing conditions. These movements can also be observed when we cruise at higher speeds.

4. IMPACT NOISES

A worn marine engine mount shows more deflection due to the rupture of elastomeric chains. More information on this link (https://www.ellebogen.com/en/how-do-the-marine-engine-mounts-loose-their-elastic-properties/)

This will cause the engine to shake and make contact with other components. This will cause noticeable impact sound.

5. VISUAL WEAR

If there are signs of significant corrosion, cracks, disconnections,permanent deformation, wear will occur at the support connection points. If you notice any cracks, this can limit the performance depending on the severity of the fissure.

The effectiveness of the engine marine mounts is based on their stiffness; any change in the shape or hardness of the rubber may be detrimental to the engine and propulsion shaft. If you notice any of these signs, you should replace the marine engine mounts as soon as possible.

Guide to detect visual wear

Based on information available on the web we have made a visual summary of which areas to check to evaluate if the boat marine engine mounts should be replaced.

1- Detachments between the bell and the rubber

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2- Presence of oil

Although some marine engine mounts have a bell that protects the rubber from oil contamination may still occur.

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3- Excessive corrosion

 

 

4- Visible component breaks

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5- Bottomed aspect marine engine mount

How can I Identify the hardness of the mount that I need to replace?

Marine engine mounts often have corrosion on their baseplate, which makes it difficult to see the hardness number on the base plate. They are often close to the fixation hole. They normally show one of the following numbers 35, 40, 45, 55, 65 or 75.

This indicates the hardness of the rubber. This information is important as this number reflects the stiffness of the mount. In some cases, you may need to scrub the metal plate to get a clearer image of the stamped number on the metal plate. Below is an example:


Rubber hardness stamp, not clear. Using a magnifier we can see it close to the fixation hole.

If we zoom in and change the contrast of the picture we can see “65”. This means 65 Shore Hardness.

ELLEBOGEN GT MOUNTS

Ellebogen has created a range of universal engine mounts as replacements which improve comfort engine performance onboard.

With two different sizes in four different degrees of hardness, the Ellebogen GT mounts are designed to provide the optimum insulation for a wide range of engines.

How can I identify the equivalent Ellebogen GT mount?

Ellebogen has an online shop. https://www.ellebogen.com/en/shop-online/

Ellebogen GT engine mounts have designated names for easy identification. The letter after the “GT” indicates the size of the mount. If, for example it is M, this means “medium” and the letter S, means “small”.

The number refers to the hardness of the mount. For example, if your old mount is marked with 65 on the metal plate and is a medium size, the equivalent would be the Ellebogen GT-M65.

Once you have selected a mount, you can view its specifications and download its datasheet with drawings and elastic properties by clicking on the button “Datasheet”.

Should i paint the new engine mounts?

The answer to this question is a clear No.

Marine engine mounts normally come with industrial coatings based on Yellow or silver coloured Zinc plates.

Ellebogen mounts come with a Zinc Nickel coat and a double layer Polyurethane coat. This allows the mounts to withstand a 1000h salt spray test without red corrosion. The stud is Zinc Nickel coated with a resistance of 760h in the salt spray chamber.

It is a good practice to apply grease to the bolt once the mounts have been installed.

What is the flat washer on top of the mount for?

Flat washer spreads the engine load over the bell of the flexible engine mount. The image below shows the levelling components of the mounts.

The following image shows a mount which does not incorporate this flat washer. The engines static and dynamic forces will be supported by a riveted inner core. The resistance of the rivet depends to the magnitude of the forces and how frequently they happen.

What is the Nordlock washer for?

A Mechanical fastening which is exposed to vibration and thermal expansions/ contractions, must be correctly selected. A loose nut can damage the stud and eventually break it.

Ellebogen® Marine engine mounts incorporate Nord Lock washers. The Nord lock system uses tension instead of friction (traditional systems). Therefore the bigger the tension, the bigger the fastening safety. This is particularly important to assure correct fastening when the fastenings are exposed to vibration, dynamic loads or thermal contractions.

Ellebogen® Marine engine mounts incorporate best possible components on the market. The selection of this type of system was done after testing several products, brands and systems.

The below video is very educational on how this Nordlock fastening system works.

Why does the Ellebogen GT M have a curved bell?

Ellebogen® Marine GT-M marine engine mounts incorporate a curved ending of the bell, in order to move oil from the bell avoiding contact with the rubber.

Are the Ellebogen GT mounts tested?

Yes. They have been tested to fatigue, traction and on real engine cases.

Below videos show the behaviour “before” and “after” on a complex engine to isolate such as the 1GM10 engine:

The new Ellebogen GT mounts are universal marine engine mounts. They incorporate a failsafe interlocking metal part as shown on the below image.

This feature allows them to withstand to high forces in traction.

The mounts have been subjected to severe fatigue tests giving optimum results and reliability.

If you have a similar application or engine do not hesitate to contact us.