In an engine's cooling arrangement, what happens to the jacket water?

• A. It remains in a separate loop
• B. It circulates through water jackets in the engine block
• C. It evaporates in the intake manifold
• D. It is used to lubricate moving parts

Answer: (B)

Jacket water is the coolant that flows through the engine’s water jackets to remove heat from the cylinder walls and other hot areas. The coolant is pumped into the engine block, where it circulates through these internal passages, absorbing heat as it goes. It then moves on to the radiator to be cooled and returns to continue the cycle. It isn’t used for lubrication and it doesn’t evaporate in normal operation; those would indicate different issues or system stages.