Car Care – Engine Cooling

Rust from the Radiator

This week we’re starting on an essential fluid – Ethylene Glycol-based Coolants.

Coolant in the Engine is a critical requirement due to the heat involved when the engine is in operation. As such, the various parts of the engine depend wholly on the presence of a liquid that can handle the pressure and heat generated by a healthy engine.

This Coolant write-up was conceived weeks before the release, which coincidentally is after one of our new Skoda customers had the engine overheat slowly on him. Cooling issues happen anywhere and anytime. We’d rather detect it when it’s in the workshop than on the street or even the highway to Malaysia.

Cooling System
The cooling system in a typical Audi/Volkswagen/Skoda/Porsche/Seat has the following components:

  • Glycol Coolant (G13)
  • Radiator
  • Water Pump
  • Engine Block
  • Thermostat

Water Pumps pick up coolant from the base of the radiator and pushes it through the engine block to cool the combustion chambers. From there, it returns to the radiator for heat dispersal and then the cycle repeats. It is a simple yet important method of ensuring the engine block doesn’t overheat and seize up. However, if the failure of the cooling system occurs, many things can happen like the warming of your air-conditioning – Even though the fans are spinning hard or the presence of steam from under the bonnet or even the sound of boiling, which accompanies said-steam.

Thermostat
The thermostat deserves a section of its own as it is a simple but essential component, contributing to the success of the entire cooling system.

The thermostat is a gatekeeper and a good one at that. Without it, the engine would take ages to warm up. It allows your engine to warm up to operating temperature relatively quickly. When the engine is closer to being warmed up, the thermostat slowly introduces the cool coolant from the radiator into the  and eventually the thermostat stays open to ensure the engine gets a good supply of cool coolant from the radiator to cool the system down.

The trouble begins when the thermostat no longer functions as it should. When the thermostat doesn’t open and release the coolant stuck on the side of the combustion chambers, the coolant starts to exceed its boiling point. This causes overheating to occur as the coolant exceeds its maximum operating temperature. In addition to that, copious amounts of steam might appear under the bonnet. Don’t be alarmed and don’t open anything under the bonnet till the car has cooled down.

Distilled Water
During our parents time, the common practice would be to top the radiator up with plain water or even better distilled water as we noticed low levels in the reservoir bottle. It was good practice as it was cheap to fill up with water when the coolant was low – but how often do we know how much water has been introduced into the cooling system and most importantly, what the ratio of coolant to water is at that point in time. We might even want to run on water!

Pure water might initially appear to be an excellent coolant for use. Unfortunately pure water also has a few undesirable properties. These include:

  • Pure water is corrosive to metals due to the very low dissolved solids content (ions)
  • Water promotes oxidation of metals also known as corrosion
  • Water typically contains small quantities of various microorganisms, which may grow and multiply over time

Corrosion
Metals corrode on contact with water. Corrosion is the primary means by which metal components are attacked, causing the deterioration of metal surfaces. Corrosion is an electrochemical process known as oxidation. When metals are exposed to water, they oxidize. During oxidation, the metal surface will begin to slowly dissolve, releasing metallic ions into the water. At the same time, free electrons accumulate in the metal. All ferrous metals have a tendency to oxidize – some faster than others. If not prevented, corrosion can rapidly degrade a system’s performance due to decreased heat transfer across corroding surfaces and in the worst cases lead to component failure.

The follow are some pictures of rust in cooling systems: