Temperature Gauge and MPG

W

Wibber

Member
Hi all,

Sorry, this has probably been covered before, but despite reading through previous posts on the topic, I'm still not sure if my car has a problem or not?

I've only had the car for a just under two weeks, so still getting to know it so to speak, and I have noticed that the temperature gauge does what I would say are some strange things.

Firstly, whilst on a long distance trip on the M25 by Heathrow, whilst sat in traffic I noticed the temperature gauge was resting at the bottom of the gauge on 60 degrees. A few minutes later, the traffic started moving again and the temperature started to rise again, eventually getting to 90 and staying there, in what was free flowing traffic for the rest of the journey.

Not sure if this is normal or not, as the car may well cool down whilst sat in traffic, and I haven't ever had a diesel before so perhaps this is a trait, but I am now paranoid about the temperature gauge, thinking I may have a temp sender problem.

To back this up, the car seems to take ages to warm up on some journies. For example, I did a long distance journey this morning and the car took a while to warm up, and the gauge only started to rise once the cabin temperature warmed up and I had switched my climate to Auto.

To make me even more paranoid, I am watching my MPG, both to see how much money my new diesel is saving me, and also in regards to the temperature gauge, as I presume that if the car is cold, more diesel is used by the engine???

I filled up from the red this afternoon and the car took £25 worth for only 270 miles, which is only 45 MPG, so really wondering now whether something is not quite right?

Should the temperature gauge climb quicker and then stay at 90 degrees once it gets there???

Any advice would be much appreciated. Thanks
 
The movement of the temp dial needle is not usual, for either a diesel or petrol, so you may have a duff sender. Don't panic though, it's not the end of the world!

As for warm up times, they do vary depending on whether you have the older style Webasto heater or not.

The Webasto type (which I don't think you'll have on a 2002 car) acts like a mini boiler, actually burning fuel to heat up the air entering the cabin and also the engine temperature very quickly indeed. Newer types without this heater warm up a lot slower and this is normal.

You are right that more fuel is burnt when the engine is cold and also, don't expect a massively high economy figure - the published numbers of up to 80mpg are rarely, if ever achievable in the real world. Depending on traffic conditions, driving style and so on, 45mpg isn't that bad and you can expect to take 10 mpg off that for a petrol model.

Cheers,

Mike
 
Hi Wibber
As Skipton indicated, you almost certainly have a faulty temp sender. If you have not already read it, the attached link will provide more info.
http://www.a2oc.net/forum/showthread.php?t=3208&highlight=temperature+gauge.
I think your 2002 car should have the Webasto auxiliary coolant heater. You'll soon find out as it cuts in automatically at ambient temps below 6 degC and sounds like a jet fighter when it fires up. The Econ button overrides it and I use this when pulling the car out the garage etc, to stop the heater running through its cycle when I only want to run the engine for a minute or two.
The long warm-up time is one of the drawbacks with all small high efficiency diesel engines which is why early cars had the Webasto heater. It's quit an expensive piece of kit which is why Audi stopped fitting it (they claim they lost money on every A2 made)and fitted a cheaper electric heater to supplement the cabin heater. Only drawback is this does not warm the engine up faster in cold weather.

Cheers Spike
 
You must log in or register to reply here.
Back
Top