Cooling and Lubrication flashcards

It is a wax-pellet valve that stays closed while the engine is cold for quick warm-up and opens near its rated temperature (often about 180 to 200 F) to send coolant to the radiator. It does not cool or pump.

Stuck closed: coolant cannot reach the radiator, so the engine overheats quickly and the upper hose stays cool. Stuck open: slow warm-up, low gauge reading, weak cabin heat and poorer fuel economy.

The spring-loaded cap holds pressure, raising the boiling point (about 3 F per psi). Opening it hot drops pressure suddenly, letting scalding coolant flash to steam and spray out.

Only at idle or in traffic suggests weak low-speed airflow, such as a fan that does not run. Only at highway speed or heavy load suggests limited capacity: clogged radiator, low coolant or weak pump flow.

Sump, pickup screen, oil pump, filter, galleries, bearings and other moving parts, then drainback to the sump. The pump makes flow; the filter only cleans.

It is a viscosity rating. The number before W (winter) rates cold-temperature flow, lower meaning better cold flow; the number after the dash rates viscosity at hot operating temperature.

No. Level is how much oil is in the sump; pressure is how hard the pump pushes oil through the passages. A full engine can still have low pressure from a clogged pickup, worn pump or worn bearings.

$Q=mc\Delta T$: Q in kJ, m in kg, c in kJ/(kg$\cdot$°C), $\Delta T$ in °C. Rate $P=Q/t$; 1 kJ/s = 1 kW. 6 kg, c = 3.6, 15°C gives 324 kJ.