MDT Chpt. 8 key terms - Engine Cooling Systems

thermostat

The component used to regulate the operating temperature of the coolant

electrolysis

The process of pulling chemicals apart by using electricity; the chemical decomposition of metals such as iron, steel, and aluminum caused by passing an electric current through liquids.

Nalcool

a Brand of supplemental cooling additive

water pump

a centrifugal device used to circulate coolant through the engine cooling circuit

double pass radiator

a counter-flow radiator in which the coolant is routed to make two passes, which improves cooling efficiencies because the coolant is in the radiator for longer periods.

counter-flow radiator

a double pass radiator that coolant is cycled through U column tubes; it has higher coolant efficiencies than other radiator designs.

thermatic fan

a fan with an integral temperature-sensing mechanism that controls it's cycle

silicone hose

a flexible part between the radiator and the engine block; more costly than rubber type but have a longer service life and can withstand greater temperature extremes.

radiator

a heat exchanger; the part of a vehicle's cooling system that transfers the heat from the coolant to the outside air

cross-flow radiator

a low-profile radiator with the entry and output tanks at either end, and the coolant flow is horizontal

water manifold

a manifold mounted on the side of the diesel engine that ensures an even distribution of coolant through the engine block, and consistent cylinder temperatures.

zinc anode

a metal that helps neutralize cathodic damage or counteract corrosion.

down-flow radiator

a single pass radiator with the entry and output tanks at the top and bottom end, with coolant flowing down through vertical tubes via gravity.

shutterstat

a temperature, pneumatic switch used to manage air shutter operation

ram air

air forced through the radiator core as the truck moves down the highway; air fed into engine cooling and intake circuits by the velocity of a moving vehicle; it increases with vehicle speed.

serpentine belts

also called poly-V belts; a multi-grove belt used on fan pulleys that are thinner and wider than older belts, making them able to handle much greater torque and speed without belt-flip

poly-V grove belts

also called serpentine belts; a multi-grove belt used on fan pulleys that are thinner and wider than older belts, making them able to handle much greater torque and speed without belt-flip

propylene glycol (PG)

antifreeze that's less toxic than ethylene-glycol antifreeze; it must be tested with a refract-o-meter; it cannot be mixed with EG because it is impossible to measure the level of antifreeze protection with a refract-o-meter or hydro-meter.

single pass radiator

any radiator with cooling tubes that run vertically from the top tank to the bottom tank so that the coolant runs in a down-flow direction.

supplemental cooling additives (SCA)

chemicals added to antifreeze to prevent cavitation or corrosion in the cooling system.

extended life coolant (ELC)

coolant premix with a longer service life and minimal maintenance

heat exchanger

device used to transfer heat from the engine coolant by either conduction or radiation.

waterless engine coolants (WECs)

engine coolants that blend glycols and soluble additives, but not compatible with water. Recently popular because it's high boil point temperature can eliminate cavitation and reduce maintenance.

heater core

heat exchanger that uses engine rejected heat to warm cabs, bunk and passenger compartments.

hydrometer

instrument used to check the specific gravity of a coolant mixture

refractometer

instrument used to to measure the the antifreeze protection of a coolant; provides more accurate readings than a hydrometer and designed to read

antifreeze

liquid solution added to water to create an engine coolant solution used to raise the boil point and lower the freeze point.

fan clutch

located in the engine fan hub, it can be an on-off device or it can be managed electronically by the engine ECM to run at a proportion of the fan hub speed

polymeric band clamp

manufactured from a heat-sensitive material that shrinks to conform to any shape of hose and housing when heat is applied.

pH

measures the acidity of the coolant; evaluates the acidity or the alkalinity of a substance

ethylene glycol (EG)

more commonly used antifreeze of higher toxicity than propylene glycol; has a limited lifespan, and therefore needs change every year; it cannot be mixed with PG because it is impossible to measure the level of antifreeze protection with a refract-o-meter or hydro-meter.

cavitation

pitting or erosion in the liner wall of engines that use wet cylinder liners, which can cause major engine damage; vapor bubbles in the coolant implode and collapse, then they attack the liner causing the pitting and erosion.

constant tension hose clamps

pressure clamp used to apply a constant tension to a hose clamp using a spring; the tension is set by a screw

constant dimension hose clamps

pressure clamps using a screw; the dimensions does not change and it does not adapt to temperature changes. Not used currently, rather only used as a replacement method.

diesel coolant additive (DCA)

proprietary supplemental coolant additives

total dissolved solids (TDS)

proprietary supplemental cooling additives

electrolytic action

stray voltage damage of metals by electrolysis; causes engine pinholes in heat exchangers and erosion pitting failures of cast iron liners and cylinder blocks; also called cathodic action or galvanic action

fanstat

the earliest means of controlling engine fan cycle and speed, with an on-off device that used air/electric/oil pressure to engage or disengage the fan clutch.

rejected heat

the heat energy of a fuel that the engine is unable to convert into useful mechanical energy. it is transferred to the atmosphere by either the exhaust gas or the engine cooling system.

weep hole

the lower port or hole in the outer housing of a water pump that allows coolant to discharge; trace discharge is normal, but steady drips indicate seal failure.

headers

the manifold deck to which the coolant tubes are attached

convection

the transfer of heat by gas or liquid currents from an object to the air surrounding it, as in the movement of air through an engine compartment.

radiation

the transfer of heat by heat rays that don't require matter; the turbine housing of a turbocharger radiates lot of heat.

conduction

the transfer of heat from one solid to another solid, as in the transfer of heat through a cast iron cylinder block.

coolant filters

used to filter engine coolant; The filters condition the coolant by softening the water to minimize scale deposits and acts as a rust preventative.

actively pressurized cooling system (APCS)

way to raise cooling system pressured using controlled on-board compressed in order to raise the boiling point of the coolant