Cooling temp query

[kervaig]

Does the thermostat open gradually and vary the opening depending on temperature or is it just fully open or closed. Reason I ask is my temp gauge has been showing strange readings over the last couple of weeks, for the 35 months I’ve owned the car the gauge has risen to 82/83 within 2/3 miles from cold and stayed there, the only exception being heavy traffic in warm weather when it’s risen to 90. Now it’s struggling to get to 80 (still within the usual 2/3 miles) then drops down to 70/75, creeps up to almost 80 and then seems to slowly fluctuate between the two extremes. Also, on a 250 mile trip last week the gauge sat at 80 the whole way with one exception where it rose to it's normal reading for a very brief period then back to 80 again. All very perplexing.
I’m pretty sure it’s the stat, just looking for an other opinion.
Ta
Jim

[Windrew]

only thing i can think is it is very cold at the moment?

[montyfox]

The stat should open in a fairly progressive movement, it does not snap open or snap shut. And yes, the stat will be open by varying degrees dependant on the coolant tempertature.

Take the stat out and tie it to a bit of cotton and dump it in a jug of boiling water, note the action of the opening. If its very jerky then its time for a new one.

Current ambient temp. are going to play a part also, mine was running cooler than usual.

If your coolant system is sludged up, this will affect the coolant temp as well.

[kervaig]

Changed the thermostat at the weekend and normality seemed to have returned i.e 70 mile trip yesterday temp reading a steady 82/83 again. Unfortunately the temp fluctuations reappeared again today along with a new problem, when the gauge was reading it’s lowest (the second of the two close together marks – 70oC?) the revs at idle dropped from 750 to 500rpm almost but not quite cutting out, it may just have been coincidental but........ Coolant sludge isn’t an issue as the system was drained 18 months ago. Again, any suggestions most appreciated.
Jim

[Scottyboy]

I'd replace the coolant temperature sensor first if I were you - only about 12 quid iirc and easily done yourself.

Check this thread for it's location...

http://www.astraownersclub.com/vb/showthread.php?t=97444&highlight=coolant+sensor

[Daz_Arden_GSi]

ive got a GSi 53 plate with 32k on the clock and mine sits at 80 and only goes up further if im stuck in traffic and then when i move off again it goes back down.

i dont mind it doing that at all. seems perfect to me?? im gonna keep an eye on this post, let me know what u do about it.

oh and ive replaced the cambelt/water pump/Coolant lately aswell and it was still doing it before that.

[kervaig]

Replaced the sensor last night, temperature now sitting at 90oC – wtf!! Checked the part number, muppets gave me the wrong one. Replaced the replacement sensor tonight and bingo back to normal, sits at 82/83, idles 750rpm never misses a beat. Also, got my replacement Irmscher spoiler from LMF today – all’s well in my universe for another 5 minutes – oh and I can now change a sensor in 10 mins!
Daz, I wouldn’t get to worried if I were you I read in another post that the gauges aren’t all that accurate and you’ll struggle to find two the same, so if yours has always sat at 80 then should be okay unless like mine where the temp would drop way down for no apparent reason.
Thanks for the advice folks
Jim

[astranoob]

Replaced the sensor last night, temperature now sitting at 90oC – wtf!! Checked the part number, muppets gave me the wrong one. Replaced the replacement sensor tonight and bingo back to normal, sits at 82/83, idles 750rpm never misses a beat. Also, got my replacement Irmscher spoiler from LMF today – all’s well in my universe for another 5 minutes – oh and I can now change a sensor in 10 mins!
Daz, I wouldn’t get to worried if I were you I read in another post that the gauges aren’t all that accurate and you’ll struggle to find two the same, so if yours has always sat at 80 then should be okay unless like mine where the temp would drop way down for no apparent reason.
Thanks for the advice folks
Jim

What are you saying? Shall the temp be sitting at 82/83 when it's normal? I have "problem" with my coolant temp...I thought, until I read this. I spoke to a local dealer, and they looked up the normal values of the coolant sensor, and told me it was at 92. I'm still getting heat in the car though, so that's not the problem. Just the coolant temp. I'm also getting a fault code on the coolant temp, so there seem to be something that's causing this.