Wifes VX 'overheated' - or did it?

[psyolent]

My wife has a VX2 Berlina - like mine. Identical actually. Except mine is series 1. Ecotec V6.

It 'overheated' yest. Its done something similar before.
She was on the phone to me ironically when it happened ; the alarm on the dash went off for high heat, gauge was on H. Pulled over - engine off.
So she 'Facetimed' me so I could have a look.

The thing here ; is that ; theres no indicators to suggest it overheated.
1. She put her hand on the bonnet of the car before she opened it. She took her hand away - her hand was warmer than the steel and I could see the imprint of where her hand was on the bonnet. normally this would be steaming hot.
2. The fans were still running after she took the key out of the ignition. Full speed.
3. No water or coolant pissing anywhere

After the fans chilled out, I got her to turn the ignition to reds. No over heat gauge, gauge read normal. No alarms, no fans. Engine was not seethingly hot. Started car. Everything normal like nothing had happened. She carefully drove home (about 1km) and put the car away in the garage.

I got home from work lastnight and had a look.
1. Water still in overflow - no problems
2. It took about 500ml of water while i re-bled the system.
3. No overheating, nothing. all fine.
4. Best of all no milky oil.

Note in the 12+ years we've had the car, I've never replaced any of the usual culprits, radiators, water pumps, thermostats - nothing. Just done the usual coolant changes along with routine servicing.

My thoughts - couple of things. Air lock, or, seized thermostat, or, possibly (given the fan on condition) faulty sensor in the neck of the thermostat housing.

Appreciate input/thoughts

[immortality]

I'd go with a dodgy thermostat, but drive and monitor before spending any monies.

[psyolent]

so took to maccies this morning to get coffee. it ran 'colder' than usual. right.
religiously with the dummed down dead zone type gauge, these things run 1/3
brought home, swapped thermostat just now. bled er up, all good, fannies came on and made their presence known - and shut off - all good.
will monitor - and drive to work next week - she can have my series 1 - anything bad happens, RACV and day off work. weut.

[psyolent]

thermostat.
just dunked in boiling water. sealed shut.

[vlad01]

you have to boil them for a while before they open.

[VK_3800]

With the quality these days I usually test (brand new) thermostats before installing - a pot on the stove brought up to temp slowly along with a multimeter that has a temp probe allows you to gauge open and fully open temps within a degree or so. There's a lot of variation and it helps weed out the duds.

[psyolent]

yeah this didn't do shit, vlad.

good idea VK......either way the thing seems much happier now. it was driven around today ; apparently it had been running at half - they don't run there - they sit below half and about 1/3. now it runs at 1/3. will keep an eye on it ; keen to read codes and see what has been going on too.

however, i did note the lifters are VERY bloody noisy. it gets horrible rattles up inside it. it seems as it warms up though they lessen. so will be up for a set of those too. also the exhaust is rattling its ass off sounds like the baffles in something have got loose and piled up in the muffler or something. time for that to get done as well.

[psyolent]

well, no issues with the loungeroom since the thermostat change at all.
its had a few good runs up it too ; it got to gisborne yesterday and down to geelong today.

i do think its time to get rid of the magnatec oil though.