Unusual Temperature Reading From Engine Temp Gauge

[mikebeasley]

Hi all and first off, hope everyone had a nice Christmas and pleasant New Year! Now, I'm going to try and pick some brains! To help, my motor is a 2003 Signum 3.2. OK so onto the issue:

I noticed this morning that the temperature gauge for the engine didn't appear to warm up at all unless giving the car some load. If I drive at a constant speed, whether it's 65mph or 95mph, the temperature needle won't move off cold. If I either give it some acceleration or go uphill for example, then the needle will move to about 75c and then back to cold - I took the car up to 100mph and the needle moved to about 80c and settled back to cold. Sitting idle or a little light traffic, it seems to make the needle move to 75c.

So I've opened the bonnet and had a look at obvious things I know about - the coolant bottle looks the right colour, doesn't seem to have lost any or got oil in it. What does concern me somewhat is that in the oil filler neck was what I consider more than should have been of the creamy mayo stuff.

Finally, this afternoon when I went out, almost immediately after starting the engine, a cooling fan came on for about 10sec then cut out again. I drove about 40mi and nothing seems to be amiss other than the above description.

What I'd like to know is does anyone have any thoughts or seen this kind of thing before? I've done some research on here / the web in general but I'm not sure that I have a leaky gasket as I'm not losing fluid or finding oil in the cooler bottle - but, I'm no mechanic so I'm looking to you helpful people for advice.

Thanks all, Mike.

[Jezzy]

First the good news: Seems to me it's a faulty thermostat, and it's probably stuck in the open position, hence allowing too much cooling. It's probably not something far more serious such a head gasket etc, which is what you may have thought as you've looked for oil in coolant etc.

The bad news: If changing the thermostat on the 3.2 V6 is anything like it is on the 3.0 V6 (e.g. Omega), then it's a royal pain the whatsit, especially when compared to the fairly simple operation of a thermostat change on the inline 4 cylinder engines.

[markj23]

the gunk in the filler neck is a norm just remove the neck and clean or remove neck and put cap straight on the block condensation causes the reaction, and yes sounds like thermostat gone just replace