The Holden Commodores with the 3.8 V6 engine is a vehicle I see regularly, today was a VT model. During a service I always pressure test the cooling system to check for coolant leaks. This time it presented a couple of different coolant leaks. A cracked radiator – cracked down the side tank which is made from plastic. Also the heater tap which was also cracked – Once again a plastic part. The heater hose were worse for wear as they were swollen when under pressure. Just a matter of time before one split. These failures are common now as these vehicle all have a few kms on them. The plastic components have a hard life with the high temperatures and eventually become brittle and crack causing coolant leaks.
The radiator was replaced with a new unit as was the heater tap. The heater taps are very common fault at this age of commodore. That is why aftermarket suppliers offer a complete heater tap kit which comes with all 4 heater hoses, all the clamps need and the heater tap. This is the best way to carry out the repair.
After the parts were changed out, new coolant is added to the system not just water. This is very important as it stops corrosion and raises the boiling point. Then the cooling system must be bled to ensure no air is trapped in the system.