Intermittent overheating issue

[slystiguy]

So I'm having this intermittent overheating issue. It's now happened twice and I'm getting nervous. I'm upto 5000kms on a fresh build and it's been running awesome and hasn't really missed a beat. I sometimes do a lap around the port hills (nice open roads mainly empty so you can give a bit of guts) and while I'm driving them it runs mint no overheating... Today when I was just coasting down the suburban area of the hill(after doing a 5min run) the temp gauge starts climbing and sits about 1cm away from top... I pull over and let it sit for 5mins. Turn key on and it's about halfway again, start coasting down hill again and it climbs to about 2cm away from top of gauge and then slowly and steadily falls back to normal heat. I drive home and it sits there nicely at normal operating temp.

I drive this car mostly everyday and it never overheats on the flat when doing normal town driving.

The first time this happened I had been around the hills and was all the way to the bottom of the hill and just pulling out of a petrol station when it started climbing. It almost feels like an air lock or something... And I think I have a weeping leak on one of the turbo hoses. I'm going to replace the leaking hose today. I've also noticed one of my radiator fans isn't working which I will investigate.

Has anyone come accross a fault like this before? I'm hoping it's not the head gasket (no water or oil contamination).

The temp sender unit was one of the only sensors I didn't replace during the rebuild and is assumed to be 250kms old. Do these sensors fail and give incorrect readings like that?

Thoughts/help/save my bc

*specs - ej207 bottom end, ver 3 sti heads, td05 turbo(10-12psi), aluminium radiator,

On another note if anyone in chch has a cheap water temp gauge and sender they want to sell/lend me that would help me out heaps

[Rosssub]

Which fan isn't working? Main fan is passengers side, sub/AC fan is drivers side. They should both cycle on/off in test mode.

[slystiguy]

Hmmmmm I think it maybe my radiator cap. I took this "sti" one off my 2 door as it looked cool lol but it doesn't appear to be holding. Swapped back to my old cap for now. And also noticed leaks around coolant overflow area which I've fixed. Can't see anything leaking from turbo area. Maybe the leak was the cap and it was running down the engine and onto the uppipe.

Pass side not working. Will check with plugs thanks for tip

[94 Leone]

Your thermostat okay?