Volvo S40/V40 (1996 - 2004) - 02 1.9 TDCi Running temp.

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Tue 7 Mar 2006 13:11
02 1.9 TDCi Running temp. - bobda
I have a 52plate 1.9 TDCi S40, which seems to have a rock steady temperature. It takes what seems to be a normal amount of time to get the neddle to just before half way up the guage, but once it's there it never seems to move until the engine goes off!

It's either super efficient or there's a needle stop on the half way marker.

There are no temperatures printed on the guage like my last car so I don't know what it's running at.

Does anyone know roughly where it should be sitting?

Edited by Pugugly {P} on 12/01/2008 at 17:20

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Tue 7 Mar 2006 13:20
Running temp, Volvo S40 - Glaikit Wee Scunner {P}
Do you mean the needle moves very slowly up to the midpoint?
Or takes a long time before it starts to move up to the mid point? If the first , maybe the thermostat has stuck open. If the second , well it can depend on the external ambient, heater demand etc..
I always expect temperature needles to stay rock solid nowadays- the cooling systems are so much better.
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I wasna fu but just had plenty.
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Tue 7 Mar 2006 14:47
Running temp, Volvo S40 - Altea Ego
On a good healthy well sorted modern car the needle should rise to a set point and stay there - ALL the time - be it freezing cold outside or boiling hot, on the motorway or in Jam..

If it starts to vary depending on the situation, then is the time to worry.
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TourVanMan TM < Ex RF >
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Tue 7 Mar 2006 15:47
Running temp, Volvo S40 - Aprilia
The reason for this is that the temperature senders Volvo use ('thermistors') are actually composed of two different metal oxides with different temperature coefficients. The overall effect is to give a resistance vs. temperature profile which has a large 'plateau' in the middle. i.e. there is a fairly wide range of temperatures where the resistance of the sender is more or less constant, making the gauge much less sensitive over this region. If your gauge starts to rise above this mid-point then that indicates that your engine is getting *really* hot, and you need to investigate.
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Wed 8 Mar 2006 08:27
Running temp, Volvo S40 - P 2501
I have noticed this on a few modern cars i have been in recently. Old gauges used to wander around a bit, but now they all seem to be rock steady at the mid point. My Honda is a case in point.

Is this a better system? it seems less than ideal to me to have a gauge that is insensitive around the mid point - you see no change in the needle for ages until the engine gets very hot and then the needle goes through the roof in 2 seconds.
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Wed 8 Mar 2006 10:07
Running temp, Volvo S40 - Aprilia
I guess its done because its aesthetically more pleasing to have a gauge the behaves this way. Also it stops panicky owners contacting the dealer if the engine runs a bit hot (but not overheating) on a warm day when air-con is on.

On older cars (e.g. Cavaliers, older Mercs) you could actually see the thermostat cycling open/close by watching the gauge needle carefully.
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Wed 8 Mar 2006 10:31
Running temp, Volvo S40 - mss1tw
My 306 evidently hasn't got all this 'aesthetic' rubbish (Good!) as like you said, you can see it cycle as it warms up - goes to 70, then drops again, then back up to 70.
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Wed 8 Mar 2006 13:05
Running temp, Volvo S40 - bobda
Thanks for all the replies. I can drive a little easier now...

I was wondering, because as mentioned, the 1996 Alfa I drove before the Volvo used to wander a fair bit, especially when the thermostat opened up.
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