When “H” is too HOT

I got a message in my Facebook account about an overheating problem so I decided to talk about it, to somehow enlighten my less mechanically inclined friends about the subject of overheating and coolants:

Hi Sir Lord! I am Marvin, a follower of your write up.  I have a few questions about overheating problems. I have been to the shop a couple of times and the problem comes back during heavy traffic.  I am a Medrep(Medical Representative) and  drive a Toyota Vios.  In heavy traffic, my car seems to overheat especially when aircon is on. I have tried putting coolant mixed with water. The shop that I went to also check the cooling fans and they are ok. What seems to be the problem sir? Is the coolant helping? Thank you and more power to your motoring page. You rock!

Hi Marvin! I am truly flattered that someone in this planet actually follows my weekly column.   And yes, “sir” and “lord” are too much I believe.  Please call me “lord”. With regards to your question, lets dissect the problem and answer it one by one.  A  persistent overheating problem has several causes. The first one, and I should say the very basic, is the lack of cooling fluids due to leaks.

The basic cooling system in an automobile  consists of a radiator, the inlet and outlet hoses that connect the radiator to the engine, the water pump which is driven by the engine, the cooling fans(auxiliary fans) and a temperature sensor that is connected to your cars electronics, controlling the fans.  This chain of parts is vital in maintaining constant working temperature.   Any faulty part in the chain causes overheating therefore  it is important to do a step by step diagnosis. Persistent or chronic overheating can cause costly, I should say catastrophic damage to the engine.

A leaking cooling system is the number one culprit in an overheating engine. As the engine temperature starts to build up, so does pressure. Cooling liquid is then forced to escape through the leak(s).

Airconditioning and traffic obviously are ingredients to engine overheating . Added loads to an engine like airconditioning, lights and electronic gadgets can drain your battery of the required power that it has to supply to the cooling fans. The heat during traffic jams is sucked-in  your radiators, in effect lessening  cooling.

Faulty temperature sensors can also cause overheating as they control the cooling fans of the radiator. Sensors usually get busted at around 30,000 to 40,000 kilometers mileage so it is essential that you have it checked by a qualified service center.  

As for the coolant, the difference between running on pure water and water-coolant mixture is enormous. Coolant  has properties that perform a number of different functions while it flows through your engine internals. The most obvious  is that coolant has a much higher boiling point than water, and can therefore hold a lot more heat without boiling over. This also means that it does not evaporate that quickly compared to water.  These qualities compound for a more consistent engine working temperature.  The Coolant compounds also fight corrosion in the radiator and other metal components it comes in contact with. Running on pure water alone will lead to premature corrosion of parts of your cooling system and inevitably failure. Tap(faucet) water has its own bag of unwanted chemicals  that can cause even more corrosion of parts. It is a must to fill your radiators with distilled water.

Persistent overheating usually presents an underlying problem. The usual suspects are slow leaks, weak-”about to go” cooling fans or faulty head gaskets(or the engine head itself).  I  suggest you go to a qualified service center like Toyota and request for a full cooling system check-up.  Goodluck!

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