Wednesday, January 18, 2017 Detailed Auto Topics
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Years tend to slip by and with cars, this is no exception. It is easy to forget about the radiator. Radiators get rid of heat generated by the engine. When they fail, the results will be very clear.

leaking radiator will result in overheating and damage

No car problem gets out of hand quicker than engine overheating problems

Small leaks from corrosion, allow air to enter the system. Oxygen in the air, speeds the reaction, and coolant is lost. Soon the vehicle overheats, creating several new and more severe problems, such as blown head gaskets, warped and cracked cylinder heads. Engine, transmission and even air conditioner damage may soon follow.

A simple law of physics states, that heat always moves toward cold. This principle allows the radiator to work. An internal combustion engine produces a tremendous amount of heat. Some is used to provide power, some goes out the tail pipe and a lot is dissipated by the radiator.

Engine coolant, also known as antifreeze, is circulated through the engine block and cylinder heads by the water pump. The engine is far hotter than the coolant, so the heat moves into the coolant. Coolant is then circulated to the radiator where heat is transferred to the cooler surrounding air.

parts of a typical radiator

Most radiators work in a similar fashion. There is an inlet tank, where hot coolant enters. From the inlet tank, the coolant flows through the core. The core is constructed with a series of very thin tubes and fins. Air flow through the core, removes the heat and much cooler coolant exits into the outlet tank. There is often also transmission fluid and oil coolers included in the radiator tanks.

view of single and double radiator core with tank removed

The more surface area a radiator has, the more heat it is capable of getting rid of. Adding tubes is one way to increase surface area. Some radiators use a single row of wide tubes. Double, triple and four row models are also used. As radiators get thicker, from more tubes, it is more difficult for air to circulate. One answer is making the radiator wider and taller, but there are limits on size, due to the body design.

Engineers very carefully match the tube size and number, fan size and many other factors. The average automobile radiator is more than adequate to handle any normal load the vehicle should experience. If a vehicle starts to overheat, there is a problem, and overheating is the symptom. Larger fans, different thermostats and additives only make the symptoms worse and fail to address the cause. Proper diagnosis and repair are the only cure.

Causes of radiator failure and overheating

Until recent years, radiators were constructed of brass or copper. These metals conducted heat very well and were very resistant to corrosion. All modern radiators are constructed of aluminum, with plastic tanks. Aluminum also conducts heat well, is very light, inexpensive, but is highly corrosive.

a few of the different coolant types on the market

To protect aluminum radiators, several specialty coolants have been formulated. Corrosion inhibitors in the coolant protects aluminum, but also have a life span. In time the inhibitors are depleted and corrosion may quickly destroy the cooling system.

Fresh coolant has reserve alkalinity and a pH of eight to nine. As the corrosion protection breaks down, pH also drops. Coolant that reaches seven is depleted and will start attacking the system.

Coolant protects the radiator, heater core, cylinder heads, engine block, water pump and all the hardware in the cooling system. Corrosion becomes extremely expensive and sometimes cannot be repaired.

engine freeze plug eaten through by internal corrosion

For example, a corroded freeze plug may require the engine to be removed to replace. Heater cores frequently require dash removal. Corrosion to engine blocks and cylinder head is often non-repairable.

The only effective way to address corrosion is prevention

Properly replacing engine coolant, before it is depleted, will largely prevent most cooling system corrosion. Improperly replacing cooling, can make matters far worse. For instance, using substandard coolant, mineral and chemical rich tap water or failing to bleed the cooling system, will create many problems.

coolant reservoir showing hot and cold minimum and maximum readings

One sign of a cooling system with problems is a loss of engine coolant. The level in the reservoir should never drop below the cold or minimum mark, when cold. As the engine warms up, coolant expands. If checked when hot the coolant level should reach the hot or maximum mark on the reservoir.

Cooling systems are sealed and having to add coolant indicates a problem

Part two will discuss radiator problems and why they occur





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