Few things can make you feel as helpless as seeing the temperature gauge of your vehicle plummet to the dreaded red ‘H’.
Usually overheating is an indicator of badly maintained cars and is thus embarrassing for the owner. That being said, it can also have some extremely undesirable add-on effects and a wholesale impact on the entirety of the engine block could be adverse. However, it isn’t all bleak – cooling problems are relatively inexpensive to resolve provided you have a basic understanding of what is going on with your car when your hood fills up with smoke.
Understanding the Cooling System
It is important to understand how the cooling system of your car works. How about comprehending it by creating a mental model of the mechanics behind the cooling system?
As a general rule, every car converts one-third of the fuel energy into mechanical energy that moves the vehicle. Another one-third, which is unused, is ejected from the tailpipe. Much of the remaining one-third gets released in form of heat. Because it could cause a rise in temperature with fatal consequences, this heat should be channelled in a direction which is opposite to the vehicle’s engine.
It is the water pump’s responsibility to funnel coolant out of the radiator and into the engine, which then absorbs engine heat and cools it down. The coolant, now hot, exits the engine via the thermostat and makes its way into the radiator. Heat from the coolant is absorbed by the air that blows through the radiator, and this lowers the temperature of the coolant again. The entire schematic which the coolant follows is referred to as the “water jacket”.
At low speeds, air which passes the radiator is reliant on fans. Driving at higher speeds usually involves the air being forced through the front grille. Usually the radiator is located behind the air-conditioning assembly. With the air-conditioning turned on, air entering the radiator will already have a higher temperature courtesy the air-conditioning coil. Naturally, the warm air is not as effective at cooling the coolant down. It is for this very reason that you may have noticed signboards before steep inclines recommending you to turn off your air-conditioning.
What Causes Overheating In A Car?
Thermostat malfunctioning – A thermostat acts as the regulator for the coolant. It keeps a track of the engine temperature and determines when the coolant is required. This temperature is somewhere around the 100 degree Celsius mark when the thermostat opens a valve to let the coolant course through. Simply put, the purpose of the thermostat is to maintain the engine at an ideal operating temperature.
It may be obvious by now what happens when the thermostat malfunctions. If it stays closed when it should not be, the engine is deprived of the required coolant. What transpires then is engine overheating.
Lack of Oil – Oil is responsible for the cooling of engines in a somewhat indirect manner. It lubricates the engine which reduces the heat generated owing to the forces of friction. At times, due to relatively smaller issues like sealing or a leak in the gasket, oil enters parts of the engine which it isn’t supposed to be in. What happens then is a dip in lubrication in certain other parts of the engine block and a commensurate increase in friction and heat.
The cooling system comes with a certain in-built capacity. If the heat that accumulates inside the engine crosses this threshold, it implies dire consequences for the engine. For one, the engine can actually end up welding itself. Alternatively, excessive amounts of heat will get some component of the engine block to blow up.
Head Gasket Issues – The head gasket is placed right at the junction of the engine block and the head of the cylinder. Its role is unique in the sense that it expands thermally every time there is an increase in the temperature of the engine. In doing so, the gasket prevents the coolant lines from crossing with the oil housing. This effectively seals the cylinders apart from the fluid routing.
Gaskets commonly malfunction when the engine is not ready for the gas pedal just yet. Depending upon the point of failure, gasket failure can cause the coolant to seep into the oil circulatory channels. As a result, sludge – commonly referred to in technician parlance as ‘mayonnaise’ – is formed. This is a problem that builds up gradually and is very hard to notice. One way to appraise if this is the issue is by checking the water temperature. If the temperature is nothing out of the ordinary but sitting higher than its default configuration, the gasket needs a fix.
Air in the Coolant Lines – The cooling system is intrinsically a closed system. Due to regular degradation, small pockets of air may form and if left unattended, these bubbles gradually grow and have a full blown impact on the flow of the coolant fluid. Further, it can make the engine trick itself into believing that the level of coolant is higher than what it really is.
This might seem a bit strange at first thought, but what happens is that the air pushes the coolant in the reservoir upward. The reservoir keeps track of the amount of coolant that the engine block requires. By simulating an artificially high coolant level, the engine block never has enough fluid for its cooling purpose.
Hot spots are hard to diagnose. There is a simple job you can perform regularly to never let the problem come to a boil – it is called bleeding the cooling system and is a bit like burping your car. It is easy to do and is an amazing preventive tool.
The tricky bit about overheating issues is that it is a Catch-22 situation. Off hand, it is difficult to tell whether it is the lack of coolant volumes that is causing the overheating or vice-versa. It is really is the age-old chicken and egg problem.
One thing that is almost a certainty is that a car kept for a long enough period of time will crop up with cooling issues. So it is just a matter of putting your finger on the true underlying cause.