Testing engine coolant

When visually inspecting coolant what colour indicated that it is in good condition and functioning properly and therefore doesn't need replacing?

• Red

• Blue

• None, Colour alone is not a reliable indicator of coolant condition and should not be used as a sole means for determining if the coolant needs replacing

• Green

Simply using your eyes can be a powerful diagnostic tool when working in the automotive industry. How can you determine the condition of the coolant by observation alone?

• A warning light on the dash will come on if the coolant level is too low.

• By observing the colour. If the coolant is a dirty, rusty colour then you should recommend a radiator flush

• colour alone is not a good indication. It is the first step in the coolant testing process

• Check for sludge and other floating matter, especially around the radiator cap and expansion tank. This indicated a full flush of the system is required

What can cause an error when reading Test Strips?

• Timing is crucial. If the timing is wrong when dipping the test strips, or waiting for the chemical reaction to take place before reading the scale, it may cause a false result

• All of these answers may cause an error in result interpretation.

• The strips may be out of date

• Each brand can have slightly different instructions. If you apply the wrong method to the strips you may get a false result

When using a multimeter to test the coolant, what value indicates the coolant is in good condition, and when should it be replaced?

• A reading below 10 mV, indicates the coolant is in good condition, and above 30 mV means the coolant is too acidic and needs to be replaced.

• A reading below 100 mV, indicates the coolant is too acidic and needs to be replaced, and above 300 mV means the coolant is on good condition.

• A reading below 1000 mV, indicates the coolant is on good condition, and above 3000 mV means the coolant is too acidic and needs to be replaced.

• A reading of / or below 100 mV, indicates the coolant is in good condition, and above 300 mV means the coolant is too acidic and needs to be replaced

The coolant used in a particular vehicle has a service life of 1, 000 000 Km or 10 years. As a professional technician, how often should you check and test the coolant?

• You should always test any coolant at the half recommended service interval, and replace it at the end of the full service interval. So in this case, test it after 500, 000 km or 5 years.

• Once per year as a minimum, however, if possible, every time the vehicle drives through the shop door.

• once a year

• Every 1,000,000km or 10 years

Can the colour of engine coolant look new, be free of sludge, slime and unwanted floating contaminants, yet still cause damage to the system?

• Yes The concentration of ethyl-glycol may change, altering the freezing and boiling point but not always change colour.

• No. Even if the colour looks new there will be sludge and other contaminants around the radiator cap

• No. you can always tell if the coolant has gone bad because the colour will change

• Yes. the additives used to prevent electrolysis and oxidation from eating away the metal components of the cooling system, may become depleted, but may not change the colour.

When using a multimeter to test coolant what setting should you use on the multimeter?

• mV

• mA

• Ω

• μA

When using test strips, what is the recommended safe pH range for coolant?

• Below 7.5

• between 6.6 and 11

• between 7.5 and 11

• Anything over 11

When using a multimeter to test the coolant, how can you quickly determine if there is stray voltage giving a false reading?

• No answer here is correct

• By turning off everything in the vehicle like radio, lights, heaters, fans etc

• By turning off the ignition

• By removing the battery from the system. (disconnect the battery negative terminal)