Usage:
3208 Turbocharged Marine Engines
Description of Change: Elbows with a larger inside diameter are now used in the front water lines group on 3208 Turbocharged Marine Engines. This allows more coolant to flow through the water-cooled exhaust manifolds.
The new elbows are not intended to solve overheating and coolant loss problems caused by other mechanical malfunctions or restrictions in the engine sea water cooling circuits. Some of these problems are listed in "Causes Of Overheating and Coolant Loss" toward the end of this article.
Adaptable As: The new 7W1890 and 7W1820 Elbows are direct replacements for the former elbows when used with the parts shown in the chart and in Illustrations 1 and 2. These changes are in effect on 3208 Turbocharged Marine Engines with Serial No. 1Z3445. 3208 Turbocharged/Aftercooled Marine Engines have had these changes in effect since first production.
Illustration 1. Changes to 1W5851 and 8N761 Water Lines Groups.
Illustration 2. Changes to 1W6284 Water-Cooled Exhaust Manifold Group.
Causes Of Overheating And Coolant Loss
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- 1. High sea water intake temperature. When the temperature of the sea water is above 29°C (85°F), the jacket water temperature will increase in direct proportion to the increase in the sea water temperature. This will decrease the amount of the cooling system reserve capacity.
- 2. Too high of an antifreeze concentration in the engine cooling system. Use a mixture of water and cooling system conditioner to provide a 3 to 6% concentration of conditioner. Use antifreeze only if freeze protection is needed. Mix ethylene glycol antifreeze with water in the concentration needed for the lowet expected outside temperature.
Higher jacket water temperatures can be expected when an antifreeze solution is used due to the poorer heat exchange characteristics of the ethylene glycol mixture.
- 3. Insufficient sea water flow through intake system. Reduce sea water flow resulting from fouling of the sea water inlet, strainer, sea water pump, or heat exchanger will cause higher than normal engine jacket water temperatures. Regular inspection, cleaning, and maintenance is necessary to prevent sea water scale buildup and decreased sea water cooling.
- 4. High engine room temperatures. High ambient air temperature, poor engine compartment ventilation, and engine exhaust drawn back into the engine compartment will increase the air intake temperature. This places a higher demand on the cooling system.
- 5. Increased engine load. Increased load on the engine can occur when one or more of the following conditions exists:
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- a. extra or above average weight in the boat
- b. fouling of the boat hull
- c. bent propeller or propeller shaft
- d. improperly sized propeller
- e. misaligned prop shaft
- f. tight seal on the propeller shaft stuffing box
- g. any engine system which is malfunctioning or out of adjustment
- a. extra or above average weight in the boat
The above conditions will increase fuel consumption and place a higher demand on the cooling system.
- 6. Low coolant level in the cooling system. For proper cooling, maintain coolant level to within 12.7 mm (.5") below the bottom of the fill pipe in the expansion tank. Overheating and/or overfilling will cause the coolant to be expelled from the expansion tank thru the overflow tube. If occasional coolant overflow from the expansion tank occurs due to overfilling, installation of an automotive-type coolant overflow reservoir may be desirable.
- 1. High sea water intake temperature. When the temperature of the sea water is above 29°C (85°F), the jacket water temperature will increase in direct proportion to the increase in the sea water temperature. This will decrease the amount of the cooling system reserve capacity.
Coolant leakage or compression leakage into the cooling system can also cause a low coolant level.