Hey guys I took on this job and im stuck! It was overheating so we did the obvious first. Replaced thermostat and resovoir. Test drove and still overheated. Replaced water pump and it helped but still overheating. Ran a pressure test and holds pressure. Radiator is new. No coolant in oil. What next? Any help will be greatlg appreciated. Thanks

 

Is the temperature actually what the sensor is telling you?
Is the radiator clean inside & outside?
Fan working as it should?
Good airflow through the radiator? All the original air baffles & shrouds in place?
Did a hose collapse internally and block the water flow?

 

Yes the temp is reading correctly. It starts gushing out of the resvoir. No trash or anythkng blocking the radiator. Everything is in place. Took it to the Mazda dealership and they had to tear to the engine to diagnosis it. Nothkng has been changed or removed from OEM. When it overheats the gauge goes up to 3/4 of the way but dosent go any further. Just stuck now and do not know what else tk do.

 

Can you confirm the fans are working?

Try wiring the fans up full time, go for a drive & see what happens.

Have you flushed & backflushed the entire cooling system?

Is it loosing/using any coolant?

Have you carried out a TK test?

Pressure test the cooling system when hot(20psi), remove all the sparkplugs, crank the engine, while still pressurised & see if any coolant flies out the sparkplug holes. A good test for a blown headgasket.