Overheating ???

I have a 90 fitted with a 300tdi Disco engine and box and have recently fitted an aftermarket temp gauge which is in degrees C, after a recent run of about 8 miles it was sitting at 90 degrees then about an hour of greenlaning it was sitting at 80 - 85 then on the journey home which was around 6 miles it suddenly went up to 100 as i got home. After letting it cool down I checked the coolant level and it was fine.............any ideas why the sudden rise??
Regards Andy

13aldy13 said:

I have a 90 fitted with a 300tdi Disco engine and box and have recently fitted an aftermarket temp gauge which is in degrees C, after a recent run of about 8 miles it was sitting at 90 degrees then about an hour of greenlaning it was sitting at 80 - 85 then on the journey home which was around 6 miles it suddenly went up to 100 as i got home. After letting it cool down I checked the coolant level and it was fine.............any ideas why the sudden rise??
Regards Andy

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Whats the betting you blocked yer fad fins with mud.

surely your engine is too cold at 80 - 85? Anything up to 110c should be ok? That's why people need anti-freeze. It raises the boiling point of your coolant to well over 100c. I have another car which has an ideal operating temp of 102c, that is petrol though, and I am talking in a general sense, so I might be talking absolute arse </disclaimer>

allways thought it was bein a pressurised system that upped the boilin point

Ethylene glycol - Wikipedia, the free encyclopedia

boiling point of pure anti-freeze is over 190C

According to that page, a 50:50 mix of water/anti-freeze gives you a boiling point of 107C, and being under pressure will raise it even higher!

oil dripper said:

allways thought it was bein a pressurised system that upped the boilin point

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It is mostly pressure that raises the boiling pint of the coolant water.

In round numbers,

with NO added pressure, the water will boil at 100°C / 212°F that is, in a pan on the stove or with the radiator cap off.

If a 15 pound pressure cap is fitted, such as on a Pressure-Cooker or the car radiator, the water won't boil until it reaches about 120°C / 250°F. which is VERY hot.

Because of this, we have to keep in mind that if the system is pressurised, and is hotter than 100 degrees C, the water will practically explode out the filler hole if the cap is taken off and the pressure released. This can be very violent, and many people have been badly scalded doing it.

All our engines are HEAT engines, and they are at their most efficient the hotter they get, up to the point the whole engine goes into melt-down.

In a power station, using steam to drive turbines, the water in the boiler will be up around 375°C / 700°F and under a pressure of 220 BAR / 3,200 psi! After that they super-heat the steam even hotter, well over 500°C and sometimes nearly double that.

A burst pipe there would be quite exciting!

CharlesY

does anyone know the ideal working temp of a 300tdi? (also interested in 2.5na which is what I've got in mine)

tombardier said:

does anyone know the ideal working temp of a 300tdi? (also interested in 2.5na which is what I've got in mine)

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Around the middle of the guage Tom LOL .

Id say a around 96degs for normal engine temp

That's why people need anti-freeze. It raises the boiling point of your coolant to well over 100c

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Anti-freeze is mainly for ( apart from the obvouse ) a rust inhibitor , stops your motor from rotting from the inside out ..

.

I have the same on mine. I am running a 300TDi in my 1990 90" and after fitting a TIM electric gauge i was getting readings of 95 on a normal run pushing 100 towing a caravan up a long incline and working the engine hard. I was initially worried but after lots of checking and no coolant loss i have now accepted that this is the normal running temp and have given up worrying. I changed the head gasket and fitted a new rad and thermostat when i did the conversion so knew that it was unlikely to be a problem with any of these. I am running an electric fan which never seems to cut in so i might need to look at the setting of that if we ever get a hot summer and i am towing but otherwise what you are getting seems to be normal when compared to mine.

yellowbelly said:

I have the same on mine. I am running a 300TDi in my 1990 90" and after fitting a TIM electric gauge i was getting readings of 95 on a normal run pushing 100 towing a caravan up a long incline and working the engine hard. I was initially worried but after lots of checking and no coolant loss i have now accepted that this is the normal running temp and have given up worrying. I changed the head gasket and fitted a new rad and thermostat when i did the conversion so knew that it was unlikely to be a problem with any of these. I am running an electric fan which never seems to cut in so i might need to look at the setting of that if we ever get a hot summer and i am towing but otherwise what you are getting seems to be normal when compared to mine.

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A good thing to do when you have an electric fan is to fit a MANUAL ON switch to it, that you can hit on the dash.

This means in traffic, heavy work, slow off-road and so on that you can make the fan run BEFORE the engine gets too hot.

It also ventilates the whole engine bay, and helps keep the place cool.

CharlesY

Sounds like a good idea. Particularly in the summer when towing. I will have a look at doing it over the xmas break if the weather isn't to bad.
Thanks.