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smithsta

Green Coolant Light

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hi

my first post on here I have just purchased a yaris 1.4 diesel, I have noticed that there is a green coolant light staying on for quite a while with the word cool underneath it does eventually go off after prob around 10 mins is this normal?

thank you

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Yes, perfectly normal. Diesels usually take longer to warm up than their petrol counterparts (better thermal efficiency). It will possibly take longer too, when the weather turns colder.

The Yaris 1.4D4D I had took a similar time and about 5 miles driving at 40/50mph.

In comparison, my petrol Yaris takes around 4 minutes for the light to go out.

I suspect too, that when the light goes out the engine hasn't yet reached operating temperature either.

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Its also possible that your thermostat is on its way out and sticking open, causing the car to take longer to warm up. This will result in overcooling, and poorer fuel efficiency ultimatly.

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Our Yaris d4d takes about 4 miles driving on the flat to extinguish the Green light. Our petrol Jazz takes 1 mile.

Of course if I drive either up the one mile long 100 meter high hill outside our gate, it takes considerably less.

I've not heard of any Yaris thermostat failing. Ours is 13...and works (touch wood).

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Yes, perfectly normal. Diesels usually take longer to warm up than their petrol counterparts (better thermal efficiency).

I don’t think it’s that simple, that diesel engines take longer than petrol engines to heat up because of greater thermal efficiency.
Diesel engines get more power from burning hydrocarbon fuels because they burn it at a higher temperature than petrol engines do. So they have higher cylinder head and piston ring temperatures and the internal pressures are higher. So to withstand this, diesel engines are bigger, heavier and clumsier than the equivalent capacity petrol engines.
It’s in the best interests to get any IC engine up to its operating temperature as quickly as possible but manufacturers typically overcool their diesel engines because if they ever have to be worked hard they get very hot indeed. So they’re operating marginally at the top end and the poor driver has to suffer the consequences in winter time with a cold heater.
The last diesel engine I had was brutally cold in winter and I went looking for a winter thermostat to help it but couldn’t get one any higher than 80 C while thermostats for petrol engines are readily available up to 94 – 96 C. Just another reason why petrol engines are better.

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I've not heard of any Yaris thermostat failing. Ours is 13...and works (touch wood).

How would you know though, unless driving about with a scan gauge in constantly telling you what temp the engine is? Its the joys of not having a temp display on the dash :(

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I had a 2 litre BMW diesel which warmed up very quickly - at least hot air thro the fan.

A Vauxhall Vectra 2 lire diesel took much longer.

Our Yaris 1.4 diesel was fairly quick.

Now I have a i30 1.6 diesel and thats taking a much longer time, dreading winter, it will be colder for longer in the "cockpit". The wife now has my 1.4 diesel and she will be as warm as toast and I will still be cold.

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I had a 2 litre BMW diesel which warmed up very quickly - at least hot air thro the fan.

Sounds like it had an auxiliary heater rather than the engine warming up quickly to be honest.

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