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After a water pump is changed, should the cooling system be pressure tested and checked for leaks?

Eight weeks after having the water pump replaced on our vehicle the heater matrix started leaking. This resulted in a head gasket failure.

We have been told by a radiator repair specialist that if the cooling system had been pressure tested after the water pump was replaced the garage would have discovered the leaking heating matrix.

Richard

Yes, the cooling system should have been pressure tested after the water pump was replaced and I would be most surprised if the garage did not do this. If they did, there is a good chance the pressure test did not indicate any additional problems at that time.

Because a cooling system is pressurised there will always be pressure applied to the weakest point. In your case once the water pump was replaced the next weakest point was probably the heater core and the slightest amount of weapage could easily turn into a much bigger problem very quickly .

No doubt once the heater core was removed there were signs which indicated its condition was far from perfect but it’s hard for any garage or mechanic to make those calls when the heater is still mounted inside the car.

Short of replacing every hose, pipe and other associated parts connected to the cooling system, it is very hard to guarantee there won’t be any future leaks after any repair is carried out.

What I would say however is this; working on a cooling system is fraught with danger for the reasons I have outlined above. Once obvious leaks have been repaired the garage/mechanic should run a trained eye over all the obvious places to check for dampness and weaknesses that may create possible future problems. They should not rely on a pressure test alone.

The garage should also sit down with their customers and explain the need for them to keep an eye on the water level and the temperature gauge on a regular basis after any cooling system repair to ensure there are no further problems. They should demonstrate how and when to do this. If it suits, they should also encourage a return visit to recheck the levels themselves (free of charge).

In other words every effort should be made to avoid exactly what has happened to you. You are not the first to have this happen and unfortunately you won’t be the last.

It could be bad luck or it could be a job that could have been done a little more thoroughly. The garage could argue eight weeks is a long time after the water pump replacement and because of this they may not accept any responsibility.

Moving forward; part of the head gasket and heater repair should be a thorough check of the main radiator core itself. If the heater core is in poor condition I imagine the main radiator core will need at least a flush and an individual pressure test to check its longevity.

It can become a never ending and expensive exercise.