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Temperature Guage

Hope Someone can help

The car is a Vauxhall Astra 1.4 16V W reg (2000) I have had a problem recently with the thermostat making the car run cold ie wouldnt rise past 80 on the guage, so replaced it along with the Temperature sensor after advice from a garage and drained/ flushed/refilled with Vauxhall coolant at the same time . Now the vehicle warms up fine until the needle sits just past the middle of the guage ie 90c is this right? Also on a run ie motorway the guage rises slightly past 90 then moves back down a bit then rises past the mark again is this the right behaviour? The cooling fan kicks in if the car is left idling or in traffic and cycles with 2-3 mins between . I guess my question is where should the needle be on the temp guage as im a bit worried its now running too hot! Prior to the old thermostat going the guage sat just before the middle line. Could this be an airlock because i filled it up incorrectly as someone else said might be the case or is this normal? Should i drain/bleed the system? And is there a specific way to bleed this car?

Any advice would be gratefully recieved to settle my mind.

Damian

Reply to
damian.tomlinson
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Well, the midway point on my SD1 is 100C. ;-)

But all cars will change their running temp according to conditions. BMW use a gauge that sits exactly half way, but it's not reading the actual temp. It's driven off the ECU which translates any 'normal' temperature to exactly mid gauge. If it goes below or above this range the gauge shows it same as a 'normal' one. But you can go into a test mode where the OBC shows the actual temp, and it's all over the place. ;-)

Reply to
Dave Plowman (News)

Assuming you've fitted an 88degC thermostat then that's about right, allowing for gauge inaccuracies...

Yes, the temperature will fluctuate slightly either side of the thermostat's rated temperature. The fact you notice it shows that your gauge is sensitive and responding quickly (unlike many!)

As long as the fan comes on long before the gauge enters the red, and it goes off reasonably soon (about 2 minutes or less at idle, depending on the air temperature outside), then I'd say it was working fine.

The Haynes manual or your friendly Vx dealer should be able to tell you what temperature thermostat is needed - hopefully you noted the rating of the one you fitted, and the original?

Assuming it uses a sealed expansion tank then you can warm the car up to normal temperature with the cap off and this, along with gently squeezing the rubber hoses, should be enough to get the air out. Don't forget to have the heater control set to "hot" and you only need to have the engine idling. Once the fan has cut in/out then replace the cap and take it for a run.

Darren

Reply to
Darren Jarvis

The Thermostat that i replaced was 92deg C and the new one was the same rated temperature!

Should the fan come on after being on the motorway for 15 miles shortly after slowing down at this time of year?

Do you think i should drain/refill/bleed to be on the safe side or leave it for a few weeks?

Damian

Reply to
damian.tomlinson

I don't know. Maybe somebody with more experience of your particular model can help? 92degC seems quite high and IME the fan switch tends to actuate at less than 100degC, so with such a small margin it may be normal behaviour.

If you do decide to, make sure you fill the system slowly, slackening any bleed bolts that may be fitted (ala early Rover K-series), or even disconnecting the radiator top hose. Once it is filled idle the engine with the cap off until the fan runs.

Darren

Reply to
Darren Jarvis

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