Head gasket or bust water pump?

[Bigfella666]

Doogs

With mine I was unable to tell the difference in the heater output both before and after matrix change but boy did I notice the difference re the coolant res bottle not overflowing. Using the heater or not will make no difference in my experience.

Like I say half hour job once you have some coolant hose and 2 jubilee clips, I seem to recall Robert Spinner has a helpful demo YouTube, clearly you have nothing to lose by giving it a go.

And if you do this and change the res cap and it makes no difference you can exclude the matrix as the cause of your problems.

This will then leave you in the position of knowing you have a blockage somewhere else ( some clown mixed different coolant types ? ) or troubled water pump be it seized or that rare beast, impeller broken ?

Best of luck, when I had this problem it really knawed at my sanity, particularly with voices of vast experience telling me it was head gasket failure when it was not !