Part 1. Preparation and safety
Objective
- Check and adjust coolant levels and test coolant quality in a vehicle with a recovery reservoir.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Always be very careful when opening a radiator cap because the cap keeps the coolant under pressure to raise its boiling point. Sometimes even the pressure in a warm engine can force the coolant to spurt out when the cap is released.
- Always cover the radiator cap with a rag to catch any hot spray.
- Always wear eye protection.
- NEVER open a radiator cap on an overheated engine; wait for it to cool down first.
- Always make sure that you wear the appropriate personal protection equipment before starting the job. It is very easy to hurt yourself even when the most exhaustive protection measures are taken.
- Always make sure that your work area/environment is as safe as you can make it. Do not use damaged, broken or worn out workshop equipment.
- Always follow any manufacturer's personal safety instructions to prevent damage to the vehicle you are servicing.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- There are two correct level marks on the reservoir because the coolant in the system expands and contracts in volume depending on how hot it is. The coolant level should be at the lower mark when the vehicle is cold. The coolant level should be at the upper mark when the coolant is hot.
- If the reservoir is completely empty, add coolant until the level is up to the appropriate mark for the engine temperature. Then run the engine until it is at its normal operating temperature, and check the level again. You will probably need to adjust the level again.
- For each 10 kPa increase in the radiator cap operating pressure, it will increase the boiling point of the coolant by 2°C (1 PSI for each 3°F).
Part 2: Step-by-step instruction
- Check fluid level
Most modern vehicles have a coolant system that uses a transparent recovery tank as a coolant reservoir. Check the level of coolant in this reservoir; if the engine is hot the level should be visible at the upper mark. If the engine is cold it should be at the lower mark.
- Check protection level with a hydrometer
Before adding new coolant, check the specific gravity of the coolant in the system with a coolant hydrometer. Draw some coolant up into the hydrometer and read the mark on the float at the level of the fluid in the chamber. This will indicate the freezing point of the coolant mixture in the system, so you can tell if it has the right proportions of antifreeze and water.
- Adjust fluid level
Check the service manual for the recommended type and mixture of coolant that will produce an appropriate level of protection for the conditions where the vehicle will be used. Use a funnel to add enough coolant to bring the level up to the appropriate mark. Replace the coolant reservoir cap.
