My suspicion has been that the Four's showing mild symptoms of the infamous BHG (blown head gasket). However the car has been running better than ever, tick over is sweet as a nut. Nice and quiet, no rattles. Performance is A+. No mayonnaise or gunk under the oil filler cap or in the coolant system.

However, an inspection of the newly replaced spark plugs, revealed a slight pink discolouration on one of the plugs?



Pink being the staining colour of my coolant. This confirmed the worst in my mind. Breaching of the head gasket across the waterway.

A coolant system carbon leak test



resulted in a slight discolouration of the blue filtration fluid



to a noticeable greener shade.





The instructions confirmed the worst. The indicator should change from blue to either green or eventually yellow if carbon was present in the sample.

It’s not the end of the world. Hopefully I have caught it in its early stages. Plan is to drop the engine out. Fit a replacement TTE hg & ARP hardware. Port match the head. Remove the TVIS butterflies.
In addition the sump will be removed as a precaution to inspect the big end shell bearings and replace if necessary. I also intend to replace the hose from hell and anything else that looks to be on its last legs.

Finally intend to add a little more boost...