Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat?

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Fri 29 Nov 2019 19:31
Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat? - DPScott

Hi,

I'm new to the forum and I'd love some help with my 64 plate Ford Focus 1.6 TDCI.

I've had the car for about 3 years and I've not had this issue before.

The engine seems to take a while to heat up, but when it does it only reaches about 75 degrees on the temperature gauge before it then drops back down again and hovers around 65. The 'normal' running temperature is 80. This temperature drop happens even whilst I'm doing consistent motorway speeds.

If I come to a stop the needle will slowly drop down to the bottom of the gauge and only rise when I pick up speed, at which point the same fluctuation will happen again.

I believe it's a problem with the thermostat, as the heat coming out of the dash vents seems to fluctuate slightly in line with the engine temp gauge.

The garage I took it to tested it for a day and seem to think that it's a faulty display gauge rather than the thermostat or the water pump, but I'm just not convinced.

Any help would be great.

Thanks!

Dave

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Fri 29 Nov 2019 20:30
Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat? - elekie&a/c doctor
From your own analysis , I would say it is very likely to be a thermostat problem . Get yourself a cheap code reader, and you can check the real time temp of the engine against the reading of the gauge . I’ve never seen a temp gauge fault on these. If it were a problem, then it would need a complete instrument cluster . About £1k new . It is also coded to the car, as it contains the immobiliser security info .
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Fri 29 Nov 2019 21:32
Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat? - DPScott

That's great. Thanks. I already have an obd 2 reader but didn't think to use it to check the temp. I'll give it a go.

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Fri 29 Nov 2019 21:35
Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat? - daveyjp

Many Fords have a hidden menu feature on the cluster.

Once in you can read battery voltage, engine rpm, engine temp etc.

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Wed 11 Dec 2019 17:14
Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat? - DPScott

Update - Thanks again for the help on this. Just had my thermostat replaced and all is working well now! Engine sounds like it's running smoother too.

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Wed 11 Dec 2019 19:10
Ford Focus 64 plate 1.6 TDCI - Engine temperature fluctuating. Thermostat? - jc2

Most Ford thermostats are between 88 and 92 deg.C-the ECU is calibrated to treat this temperature as FULLY warmed-up;that's probaly why it's ruuning more smoothly-should help your mpg. too.

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