Often overlooked, routine maintenance is the key in having a long living strong engine. Following the manufacturer’s scheduled maintenance will not only yield this but also prevent costly repairs. Every model engine has a specific maintenance schedule and as an owner or captain it can become overwhelming knowing them all. At Scarano Marine we will guide you step by step through the factory specified schedule your vessel needs. A marine diesel engine has different operating systems that can be broken down into air, fuel, oil and coolant for simplicity. At Scarano Marine, we believe it’s imperative to tackle each system individually to make sure no stone goes unturned.

Air System

Every internal combustion engine requires a mixture of fuel and air to operate properly. Without air, the diesel fuel cannot burn and provide the energy needed to power the engine. To the naked eye air may appear “clean” but dust and other fine particles linger in the atmosphere. Being a vital ingredient in the combustion, an air filter is used to supply a steady clean flow to the engine. This avoids the dust particles from entering the engine and rubbing on the essential metal parts causing them to wear away. It is proven a clean air filter will not only have effects on horsepower but fuel economy and internal wear as well. Often overlooked is the maintenance of the charge air cooler (intercooler) which cools down the air provided by the turbochargers before going to the cylinders for combustion. If the air is too hot, the air volume is less than the needed amount for the right mixture and as a result it will cause black smoke and lack of power. We believe replacing the air filters and servicing the charge air coolers at the require intervals is a cost effective method in avoiding future repairs.

Oil System

Oil’s fundamental purpose is lubrication and cooling. The movements of all the metal pieces inside an internal combustion engine wouldn’t be possible without a lubricating film. Thus, it is important to maintain clean and pure oil inside the engine. The friction generated between the engines internal components result in the shedding of fine metal particles that will be contained in the oil. At Scarano Marine, we recommend conducting an oil analysis during every oil change. We are proud to offer this service and provide the customer or captain with a detailed report outlying what exactly is inside their oil. This provides great insight to the general condition of the engine along with an excellent record of the oil changes performed.

Raw Water and Coolant Pumps

A key engine component that is often overlooked but results in catastrophic failure is the water pumps. The raw water pump is no stranger in being the culprit. Some pumps, like in MAN engines, use a rubber impeller that we recommend to inspect and replace as necessary every year or 1000 hours.

Other pumps use a bronze impeller like on the MTU engines. For example the MTU series 2000 raw water pumps are notorious for causing damage that could have been prevented. The pumps are built with an external weep hole that lets you know if the water or oil seal is leaking. If the pump is leaking raw water and the problem is not addressed on time, the leaking raw water will corrode and seal the weep hole shut. The leaking raw water will not have an exit now and will start flowing through the oil seal leading to the interior of the engine. Many overhauls have had to been done as a result. Therefore at Scarano Marine we strongly recommend the inspection of the raw water pump to be done often.


In general, hoses and hose clamps are also a point to inspect. Hoses have a limited life span determined primarily by the hours in use and the engine temperatures. The clamps get rusty and corroded creating a potential leak. For example in the 2-stroke Detroit Diesel engines there are several hoses to inspect depending on the system they are employed. These hoses are known to fail and cause damage.


Fuel System

The internal combustion cycle wouldn’t be complete without air’s friend, fuel. The reaction of fuel with an oxidizer creates gases of high temperature and pressure, which are permitted to expand. As a result, useful work causes the movement needed to operate an engine. Therefore, it is critical to provide the engine with the cleanest fuel possible. This is done by various methods. Maintaining a clean fuel tank is the first step in hindering the growth of dangerous algae. Second, before the fuel reaches the combustion chamber it goes through a system of filters. A common primary external fuel filtration and water separator system is the Racor filters.Other known brands are Dahl filters and Separ filters. These filters are visually inspected and replaced as needed. Inspecting the condition of the fuel in their bowls can prevent fuel issues in the future. After this stage of purifying the fuel in the primary filters, the fuel enters the secondary filters where remaining containments are removed. Keeping the fuel filtration system clean by replacing all filters at the require intervals will lead to a stronger, healthier running engine.

Coolant System

With all that heat generated, the coolant’s job is to keep the engine at the operating temperature to provide maximum efficiency. Every engine has its appropriate coolant as specified by the manufacturer. The coolant system is usually serviced every 2 years where the old coolant is flushed and replaced with new coolant. At Scarano Marine we will adjust the right coolant concentration to the manufacturer’s specs with the use of a refractometer.  At this time it is recommended to service the coolant heat exchangers and replace the coolant filter if the engine has one. Maintaining a clean coolant system is important in preventing overheating and abnormal wear of the engine components.



Another key component in preventive maintenance are the belts. Belts are a simple and inexpensive part that holds big repercussions if not maintained properly. On engines with belt driven pumps like the MTU 183, it is of the upmost importance to perform regular visual inspections. On the MTU 183, the raw water pump and coolant pump are belt driven and since belts crack and stretch, it is critical to have them in good working condition. Due to atmospheric conditions and leaks, the pulleys can also rust and can cause a premature failure of the belt. We believe these issues can be avoided through professional care saving heartaches and costs.

Why Choose us?

Maintenance is a core component of our business, as we believe the majority of failures can be prevented. We believe the customer shouldn’t have to endure unnecessary costs and heartaches. At Scarano Marine, we have the tools and knowledge to lead you down the right path towards a healthy, long living engine.