Disco 2 Temperature Guage - Why doesn’t anyone trust it?

Hi all, struggling to understand why so many respected members of the forum warn against trusting the engine temperature gauge on a Td5 D2. I see references to “once it shows hot, the damage is done” and “it’s only relative”. Could anyone help me understand why this is the case, and are there any simple mods to provide something more reliable if I can’t trust the dashboard? Many thanks!

Its ECU driven so it'll sit in the middle from "warm" at about 78c ish (correct if im wrong!) to about 99c then hits 100c and in the red until but you could be sitting at 99c and not know kinda thing.

Ahh, got it, so not linear in line with a rise in temperature. So, maybe an after-market fitted that provides an actual reading would be a good safeguard. Appreciate the reply!

Pretty much yeah, if you want accuratr best use an aftermarket gauge (Stack are nice) or diagnostics.

bankz5152 said:

Its ECU driven so it'll sit in the middle from "warm" at about 78c ish (correct if im wrong!) to about 99c then hits 100c and in the red until but you could be sitting at 99c and not know kinda thing.

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+1 - the cynic in me might contend that this is deliberate policy by manufacturers to make the thing as uneconomic to fix as possible when the inevitable happens

GJ1 said:

Ahh, got it, so not linear in line with a rise in temperature. So, maybe an after-market fitted that provides an actual reading would be a good safeguard. Appreciate the reply!

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Absolutely! Proper aftermarket gauge is the way forward IMHO .

I might suggest that the trend toward such rubbish involves references to Harry Braverman ( a 1960's Philosopher ), and involves the term "de-skilling".

bankz5152 said:

Its ECU driven so it'll sit in the middle from "warm" at about 78c ish (correct if im wrong!) to about 99c then hits 100c and in the red until but you could be sitting at 99c and not know kinda thing.

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It's worst than that, if it was like that at least you'd know when it gets above 100 which happens quite often and doenst hurt too much for short periods, here's how it works:
- 20 - 69*C at the quarter
- 70 - 119*C at the middle
- 120 - goes up to the red
so while it's at the middle you can drive it much without even knowing it with stuck open thermosetat at 75-80*C which means high EGT and high consumption or at 110-118*C which can hurt many things on a long run, IMO a gauge which shows the real temperature on a D2 is compulsory so is an EGT gauge for those who are towing and have bigger than standard dimension tyres

Thanks! Was hoping youd come along and confirm for me

That said mine sits around 1/3 even when fully warm! Around 83 or so

Mines constantly just above halfway when it's warmed up. Doesn't go any higher on long runs but I still don't like it. Must get an EGT and coolant temp gauge sorted

OK... so really, all it does is provide some symmetry to the layout of the dashboard?

Is there a proven (simple) solution that anyone has for a real read-out... I see plenty on the internet.... I am happy enough to have a go at things but where I should go to safely take a live feed from and where I would position the sensor type advice would be appreciated from those in the know!

GJ1 said:

where I should go to safely take a live feed from and where I would position the sensor type advice would be appreciated from those in the know!

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That makes two of us

Here's the easy way how i fitted my sensors, the elbow was removed, drilled and tapped with the proper thread and the EGT went into the EGR blanking plate.... for the EGT is better in the middle right before the turbo but to warn you about some trouble it's enough there too cos if one of the other cylinders makes tricks the first will compensate and the EGT will rise there too



i pushed a straightened wire coat hanger through the grommet where the bonnet release cable goes, hooked the wires to it and pulled them in, there is a free ignition live on the front of the fusebox, only a female spade connector is needed

sierrafery said:

Here's the easy way

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....
That's grand, thanks very much

Plus one for fhat, thank you @sierrafery!

So what's the general consensus on upper limits for coolant and EGT temps?

I've read anywhere between 620 - 750°c for EGT on a td5

Thats what Ive read too

It depends on many factors but 750 should be the extreme only for short periods uphill under heavy load