after reading through here, I would go rad cap ($10aud), exhaust gas tester from filler tube kit, then new rad first steps with increasing costs. The exhaust test kit shall tell you if it is your head gasket.
I also got a pressure tester for the rad, which is the first thing a radiator shop does. Seemed ok, but doesn't really tell you if there is blockage.
I had some temp changes of late and the overflow level was low (strange, unusual). So, new cap, thermostat and pump (unnecessary) and fluids. I put some head gasket sealant goop through the coolant system. I don't usually use snake oil goop but was pressed for time and had a 2000km round trip to do straight away. Did the head gasket blue liquid test which made me feel better at least.
Things settled in the overflow but still I run a little warmer than the last 100k. I still get a bit of the goop settling on the new cap every time I check fluid levels. Don't think I like the goop, it would encourage the radiator to block up, or make a blockage worse.
Bush mechanics use to crack an egg into the running radiator if there was a leak, but that is out bush.
New fan clutch, does the job of bringing the temp down.
But my rad seems to hold pressure for much longer now, even cold in the winter morning, it still has a bit of pressure.? Anyone explain that one?
I am going to get a new rad as mine is probably 34 years old and I can get a new 4core copper for $550 aud on special , delivered.
The last thing you want is an overheating engine.
Go for the radiator before your head, after the head gasket test, head gasket is a biggish sort of job.
