Checking & replacing a coolant hose

Part 1. Preparation and safety

Objective

• Check, remove and replace coolant hoses.

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

• Never try to assess the serviceability of a coolant hose while the engine is hot. Let it cool down so that you can handle the hoses comfortably and safely.
• Always ensure the engine is turned 'off' before attempting to check the radiator hoses.
• 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

• If you find one defective hose, the chances are that the other hose(s) may be deteriorating in the same way and will soon need to be replaced. For this reason, most technicians will generally replace both hoses at once as a sensible precaution.
• You may need to use a torch to inspect the coolant hoses so that you can clearly see if the surface is starting to crack.
• Radiator hose problems:

  

• Swollen hose. This hose has lost its elasticity and is swelling under pressure. It may soon rupture.



• Hardened hose. This hose has become brittle and will break and leak.



• Cracked hose. This hose has cracked and will soon start to leak.



• Soft hose. This hose has become very weak and may collapse and close up completely.
  
• Clamp types

  

• Gear or worm-type clamp. Adjust with a screwdriver.



• Banded or screw-type clamp. Also adjusted with a screwdriver.



• Wire clamp. This spring clamp is not adjustable, and is fitted and removed with special hose clamp pliers, which have grooved jaws.
• Clamps are not expensive, so it is good practice to fit new ones at the same time as new hoses. Even if not corroded, the old clamps may have become distorted when being removed from an unserviceable hose.

Part 2: Step-by-step instruction

1. Inspect hoses and clamps
   Locate both the hoses that carry coolant between the radiator and the engine. One is at the top and the other is at the bottom of the radiator. Squeeze each hose. It should feel pliable and springy. If it feels very soft and weak, or very hard and brittle, it will need to be replaced. Look for signs of swelling or cracking, particularly on the vulnerable underside of the lower hose. Check that the clamps are holding the hoses firmly in position and are not corroded.
2. Remove hose
   Drain the coolant from the system before removing either of the hoses. Remove the clamp using the appropriate tool. If the hose is stuck and won’t pull off easily, be careful you do not damage the radiator fitting by using too much force. It is better to cut the hose in several places so that you can remove it easily. Clean the hose fittings thoroughly on both the engine and the radiator with fine sandpaper or emery cloth, so that it will make a good seal with the new hose.
3. Verify replacement
   Obtain new hoses and compare them with the removed hoses to make sure they are the same length and diameter. If the hose is a molded type, the new one must also have the same pre-formed curve.
4. Refit hose
   Apply some sealing compound to the hose fittings and place the loosened clamps over the hose ends before sliding the hose into position on the block and radiator fittings. Tighten the clamps securely about a quarter of an inch or 6mm from the end of the hose. Be careful not to over tighten and damage the hoses, but it is important they do not fall off once the pressure in the cooling system increases.
5. Refill cooling system and check
   Refill the cooling system, and then run the engine for a few minutes. Check the hose connections to make sure that there are no leaks. When the engine is at its normal operating temperature, check the tightness of the clamps again, as the clamps and hoses will both expand at different rates as they heat up.