Heat from the radiator causes the air in contact with it to heat up and expand causing decrease in density. Low density air rises and cool air moves in replacing it. Radiation is heat coming from the radiator. that is cooled by the fan. So the water thats pumped through is cooled in the raidiator withathe fan.
Indirect cooling?
A a fresh water system. it has a own closed loop more like a motor vhicle. This is for faster warm up full corrosion protection, better fuel economy and increased power. The heat exchanger has raw water passing through but the coolant exchanges the engines heat to the sea water which is done in the heat exchanger.
1.Exhaust bend, wet type
2.Engine cooling galleries
3.Vacuum valve
4.Sea water pump
5.Sea water filter
6.cooling water intake
7.Hose
Direct cooling?
Raw water passes through a heat exchanger and exits out the exhaust.What are the the problems you get with indirect and direct cooling?
Raw seawater is bad and causes corrosion and will shorten the life of the engine.
indirect cooling is hassle on marine engine because changing coolant is difficult there is more to maintain.
What is the puppose of a thermostat?
This heats up and expands at manufactures specs temprature to allow coolant and water to flow through engine once has reached operating temprature
Pressure cap?
A cap on top of a rediator designed to expand once it has reached a certian pressure to either realse or vacume coolant in or out of radiator.
Why is engines fitted with a core plug, and what is the purpose of a core plug
To expand on the chance that no coolant being in engine to prevent damage to block and heat but is usually there from manufacturing because during casting sand was inside engine and core plug was easy means to remove it.
What is the purpose of a heat exchanger?
To exchange heat from engine to the water.How does the heat exchanger work?
Water passes through pipes and and through a raw water systems and oil passes over those pipes. Then the water is expeled out the exhaust.
What is the core of the heat exchanger made of?
copper brass aluminum.How does the centrifugal circulating water pump work?
Engine heat causes fluid inside fan assembly to expand caueing fan to turn. How does a raw water pump work?
This draws water through the sea cock. it is driven by the impellar then passes through the heat exchanger out the exhaust
Why is it important to lubicate the impellor when fitting from new?
To prevent salt water corrosion from stick impellar to drive shaft and locking key inhibiting removal of impellar next service.
When fitting a impellor what should you check before refitting the housing and why?
Corrosin blockages wear marks grooves warps stainless housing plate.What is the purpose of a oil cooler and how does it work?
the internal can only be cooled by oil in which case works simialr to a radiator or an intercooler with air or water passing fins.
Why do we have Inhibitors & antifreeze?
To minimise engine corrosion increase boiling point and lower freezing temprature.
How do you test Antifreeze?
Taste it or use a tester kit.What is cavitation corrosion?
The implosion of gas bubbles on metal caused by rapid changes in pressure
What is galvanic corrosion?
It is when two metals corrodes because of electrochemical process, both metals are in electrical contact immersed in electrolyte. So you need to use the wright metals with each other otherwise the two will conflict causing corrosion You need to use a zinc node to sacrifice its self and take all the corrosion. You should fit a galvanic isolation transformer
Stray corrosion?
Defective wiring is the most common cause
melfunctioning wiresStress corrosion
begins with pitting and moving parts under pressure causes it to further cracks and damage
metals are stressed in a corrosive environment.Crevice corrosion
What is Electrolysis?
This is the result of a stray current. Galvanism produces similar corrosion. This is usually blamed by under water causes but is not the case.
How do you prevent corrosion?
Anodes and tharough cleaning and flushing after use in salt water.
Why and what is bonding in the marine industry?
Copper wire needs to be heavy enough to resit deterioration and oxidization
What are sacrificial anode made off? lead or zinc
Where would you place them in the marine industry? Gear housing, sometimes inside the engine block.
What is the purpose of a water muffle?
The raw water passes through its cycle hot from the heat exchanger then it injects it to the exhaust it can be recycled as cooled water.
Good explanations for the questions, my only comment would be, the questions would be easier to differentiate from the answers if you had highlighted them or typed them in a bold font.
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