Disco 2 Got warm at high revs

So after fixing my oil cooler leak with a 2nd hand unit and new gaskets then a busy week with the d2.
It's done about 1000 miles this week. 500 of them towing with load.
Not used any coolant or oil.
Then on the dual carriageway unloaded temperature crept slightly. Pulled over checked coolant level and it was fine..
Checked coolant today and coolant flow back to header tank is good.
Just back from stimulating when it did it.
Everywhere warm hoses like you would expect.
Lower rad hose to thermostat cold (hot the other side)
Fuel cooler to rad cold
Rad cold all over.

Stat stuck or bad rad?

Picture of the two cold hoses it's a eu3 engine with egr cooler

I'd say your thermostat is malfunctioning.

Nig43 said:

I'd say your thermostat is malfunctioning.

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I hope so ordered one this morning here tomorrow.

So new thermostat fitted, bled up, drove 4 miles home, left to cool a bit checked level again let it warm up and did a good 30mile permanently above 3k temp gauge sits a tiny touch cooler pipes highlighted are still noticable cooler but when its upto temp now I can now feel warm air being pulled from the radiator by the viscous fan so I think job done.

But having put my old stat in boiling water it has opened

stustrong said:

But having put my old stat in boiling water it has opened

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it should open at 86*C when the water is far from boiling... or do you want it to open on your vehicle when the water is boiling in it?

sierrafery said:

it should open at 86*C when the water is far from boiling... or do you want it to open on your vehicle when the water is boiling in it?

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I didn't even think about it opening late I was expecting stuck shut

It might have been stuck but got unstuck by the boiling water

stustrong said:

I didn't even think about it opening late I was expecting stuck shut

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So now it is unstuck, heat it slowly with a thermostat in the water and if it opens consistently at around 86 C add it to the emergency spares pile. I would not trust it long term though.

Si Click said:

So now it is unstuck, heat it slowly with a thermostat in the water and if it opens consistently at around 86 C add it to the emergency spares pile. I would not trust it long term though.

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I just took it home kettle water. Looks like some of the 4 holed passage ways was blocked.
Motor seems fine and Was 2am so old one just went in the bin anyway

It's just touched 198k heres hoping il get a couple week and upto 200k without another

sierrafery said:

It might have been stuck but got unstuck by the boiling water

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Which is why I said it was malfunctioning rather than completely shot.

If a waxed-based stat goes off, it will leak molten wax out. Then when it is cold, it will shut again. Then when it gets warm, there will not be enough wax in it to open it at the correct temperature, but it may eventually open once it gets really hot, by which time the damage may well be done. So basically a fubared stat blocks the water. Luckily they are cheap and easy to replace, and it one jams shut on the road, you can get it out, and use a bit of greased cardboard as a gasket, when you replace the stat holder on the engine. It'll then run better, i.e. cooler but the flow will not be right, as the shape of the stat and its opening actually matters for correct water flow. They are so cheap it is worth buying two and keeping one in the vehicle as a spare so you can fix it by the roadside.
Hope you've solved the prob and will have a trouble-free Christmas!

Stanleysteamer said:

will not be right, as the shape of the stat and its opening actually matters for correct water flow. They are so cheap it is worth buying two and keeping one in the vehicle as a spare so you can fix it by the roadside.

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My routine on board spares storage is one of the rear bins, (I have a seat on the other side). So with restricted space I limit spares to those I am really quite likely to need. Do thermostats fail often enough to warrant carrying one all the time?

Si Click said:

My routine on board spares storage is one of the rear bins, (I have a seat on the other side). So with restricted space I limit spares to those I am really quite likely to need. Do thermostats fail often enough to warrant carrying one all the time?

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Good question! Where do you stop? I have both storage bins at the back full of both tools and spares. I always carry a spare serpentine belt, a proper jack and fluids. We could start a whole thread with all this. But I do have to more or less make my vehicle into a mobile workshop when I go to France as I dread breaking down and once there for 6 months I don't have a garage or workshop with the same amount of tools as I do in the UK. As the weather is better I do actually do quite a lot of maintenance in France. And mine came with 5 seats only
Funnily enough I was thinking of starting a thread today "What spares/tools do you carry in your Landy?" While driving the wife's C3 Pluriel and the electric power steering just failed out of nowhere. My left thumb is curently crook as I cracked a bone in it working on her car, first time I have ever done myself a nasty working on a car! So heaving on the steeering wheel with one and a half functioning hands isn't easy. But I don't think I'll be carrying a spare rack/electric steering motor, and/or steering ECU anytime soon!