10 Common causes of marine diesel engines overheating

Overheating is a common symptom of marine diesel engine blockage. Marine diesels should run at 180 degrees Fahrenheit. When the temperature goes above 200, start getting worried. Dialing down the RPM’s may allow the engine to recover and run well at a more leisurely pace. Overheating is difficult to diagnose, and the only real way to solve the problem is a systemic examination of every engine element, i.e. trial and error. Here is a starter list of parts to examine:

1) Raw Water Impeller – the most common source. A spoke of the plastic impeller breaks off and clogs the raw water flow. Easy fix: buy a new impeller.

2) Mixing Elbow – Corrosion here blocks the flow. Solution is a new or boiled out elbow.

3) Heat Exchanger – Scale builds up in the heat exchanger. Solution is to snake with a wire and dip in acid.

4) Thermostat Sensor/Receiver – Is the thermostat stuck? Or is the engine even overheating? Check the exhaust temperature. How hot is the water? Shoot a heat sensor on the water reservoir.

5) Fresh Water Tank – Is it leaking?

6) Hoses – Delamination inside engine hoses restricts the flow, causing the engine to overheat.

7) Fresh Water Pump – An aluminum impeller inside the pump can corrode and limit flow.

8) Oil Cooler – Similar to the heat exchanger. You cannot snake her out because the tubes narrow at the ends but dipping the cooler in an acid bath does the job.

9) Over-propped – Too large a diameter or too much pitch can cause an engine to overheat prematurely.

10) Aeration – Air getting in from a leak in the line anywhere can lead to overheating.

Exercise 6. Answer the following questions.

1. What is normal temperature of marine diesel engine?

2. What is its abnormal temperature?

3. What should be done in order to prevent engine overheat?

4. Why is it difficult to diagnose the engine overheating?

5. What parts of the engine should be examined?

6. What other advice can you give in order to prevent engine overheat?

Watch the video “Marine engine starting difficulties” and discuss the following topics.

[https://www.youtube.com/watch?v=NZT0yZUL3qU]

1. Reducing the amount of vibration of an engine.

2. The methods of refining of the oil.

3. Why it's important to check the sea water temperature regulary?

Lesson 6. ENGINE SHIPYARD REPAIRS

Exercise 1. Read and learn the following words and expressions:

Vocabulary notes:

1. conscientious – добросовестный

2. recourse – обращаться за помощью

3. bedplate – станина

4. cast iron – чугун

5. misalignment – смещение

6. chock – подпорка

7. filler piece – прокладка

8. cylinder liner – рабочая втулка цилиндра

9. prolific – продуктивный

10. casuality – случайность

11. abrasive – абразивный

12. impurity – примесь

13. to fit a replacement part in-situ – устанавливать сменные запасные части на месте

14. to predict by computer – прогнозировать с помощью ЭВМ

15. spare parts – запасные части

16. wear and tear - изнашиваться

Exercise 2. Read, translate and discuss the text.

The conscientious engineer who is responsible for the operating efficiency of his ship takes pride in maintaining the machinery in good condition without recourse to outside help. There are conditions, however, under which this becomes impossible. The operating schedule may be such that the engineers must be available for operation most of the time and many repairs requiring the engines to be disabled cannot be done within the short time available for such work. In this case repairs are restricted practically to such items as may be carried out at sea. As the size of marine Diesel engines increases the individual parts become more massive and even routine examinations become too great a task for a small number of engineers and the limited equipment on shipboard. As a result, a large proportion of motorship repairs is done in shipyards. Such repairs may, in general, be grouped into three classes as follows: (1) maintenance repairs, or those resulting from ordinary wear and tear in service; (2) repairs required as a result of faulty design, or changes due to improvements in design; (3) repairs required as a result of accident, stress of weather, or other unusual conditions.