malcolm bell · Sep 17, 2021

Since I have changed my radiator for a larger alloy one the temperature is reading 3/4 on the dash.
I know thermostat opens around 88degrees the clock is reading about that.
Any body got any ideas.
Don't fancy cooking it.

lynall · Sep 17, 2021

I would say try a new sender, or get one of the cheap laser temperature guns off ebay and see if it agrees with the gauge.
Which engine? 200s like a stat or two, could be a bit of debris you have disturbed effecting the stats operation.
Have you done any miles in it with new rad fitted? if not it might need bleeding.

discool · Sep 18, 2021

malcolm bell said:
Since I have changed my radiator for a larger alloy one the temperature is reading 3/4 on the dash.
I know thermostat opens around 88degrees the clock is reading about that.
Any body got any ideas.
Don't fancy cooking it.

An alloy radiator is brilliant in cooling the engine as the rad absorbs more heat than brass, they have been used for years in performance cars.
But there’s a science involved, all vehicle radiators have to be cooled, therefore the D1 system involved in cooling the old brass/ copper isn’t up to the job… maybe, air flow into the front of the rad plus on a D1 the viscous fan pulling air through the rad isn’t good enough in cooling the your new larger alloy rad.

I went over to an alloy rad on a car I own around 35years ago and at first temperature gauge showed an increase, so I removed the the existing fan and fitted the largest electric Kenlow fan on the front, the problem was solved and the cooling system is still to day ok and untouched, other than replacing the antifreeze every couple of years

Obviously I didn’t have the access to the WWW back then, so just went fitted a different cooling fan, so you maybe able to do the same with you disco, and assuming its a diesel fit a V8 D1 eleven blade fan plus its viscous coupling or if easer fit a suitable electric fan/s… like ‘most up to date’ cars

malcolm bell · Sep 19, 2021

discool said:
An alloy radiator is brilliant in cooling the engine as the rad absorbs more heat than brass, they have been used for years in performance cars.
But there’s a science involved, all vehicle radiators have to be cooled, therefore the D1 system involved in cooling the old brass/ copper isn’t up to the job… maybe, air flow into the front of the rad plus on a D1 the viscous fan pulling air through the rad isn’t good enough in cooling the your new larger alloy rad.

I went over to an alloy rad on a car I own around 35years ago and at first temperature gauge showed an increase, so I removed the the existing fan and fitted the largest electric Kenlow fan on the front, the problem was solved and the cooling system is still to day ok and untouched, other than replacing the antifreeze every couple of years

Obviously I didn’t have the access to the WWW back then, so just went fitted a different cooling fan, so you maybe able to do the same with you disco, and assuming its a diesel fit a V8 D1 eleven blade fan plus its viscous coupling or if easer fit a suitable electric fan/s… like ‘most up to date’ cars [/QU

Thanks pal for reply
Will try those suggestions.would I be able to leave viscose off and use just the electric fan or not.
many thanks.OTE]

malcolm bell · Sep 19, 2021

Thank for reply.
Will try the electric fan . so would I remove viscose all together or not.
Or put fan the other side of rad.dont have any ac rad on.
Many thanks.

Zed. · Sep 19, 2021

malcolm bell said:
Since I have changed my radiator for a larger alloy one the temperature is reading 3/4 on the dash.

what did the gauge read before fitting the alloy rad?

what did you have fitted before the alloy rad? (guessing standard??)

why did you fit the alloy rad?

^^ NOT stupid questions.

some thick alloy rad cores can be too thick - they actually heat the air flowing through the core and loose efficiency so not transfering coolant heat into the air

Rich.

discool · Sep 19, 2021

malcolm bell said:
Thank for reply.
Will try the electric fan . so would I remove viscose all together or not.
Or put fan the other side of rad.dont have any ac rad on.
Many thanks.

Your into ‘try & see’ unfortunately, due to fitting a non standard rad, but yes you will have to remove the viscous coupling completely with its fan, and fit if possible in the space , the electric fan to draw air through the rad, also it gives the fan protection at the rear or the rad.
As you dont have A/C then a fan could be fitted on the front of the rad to blow air through it.

I don’t know how many blades your fan has but if you could find a 11 blade V8 fan and fit that to the your existing viscous coupling to see if it makes any difference, I say find as u don't want to waste money or your time on something that has no affect.

So onto the electric cooling fan, get the largest one that will cover the rad with out touching any other part and of course not to big making it difficult to fit, a big fan wont over cool, as like all after market electric fan they come with a thermostat, so when the rad temp starts moving up above the ‘normal running temp’ the fan starts spinning bring temp back to normal.
When the disco is moving on the open road the engine should then be a normal running temperature, if not the fan will then cut in briefly, I believe that the standard tdi runs ok without a fan fitted.

The above is based on a petrol engine, but as you have a Diesel engine there’s an intercooler to look after… No comment on that, as diesels are dark matter for me

Disco1BFG · Sep 22, 2021

First port of call is to find out, for definite, the actual temperature .... not what the LR gauge is telling you - so, either, as post #2 or fit a Durite capillary gauge - even as a temporary fix, it'll tell you the actual temp....

A laser thermometer is always worth having, and should help work out if the rad is actually working, by enabling you to measure inlet and outlet temps .....

And, another vote for electric fans - the dual fans for a D1 with air con might be available cheapish - I have them fitted to my tuned 300 Tdi .... just in case - but I'm running the standard coolant rad - even with EGT's above 600 C, the cooling system copes, and my coolant temp gauge stays in the same place ....

I'm curious as to where your IC is ... ?

Europa486 · Sep 23, 2021

As has been said check the real temperature you are getting with a laser temp gun, but on the early MK1 you have
A voltage resistor on the back of the instrument panel that drops the voltage to 9 volts,
This is so whatever the voltage main battery has the gauges only see 9 volts so are accurate,
But if the resistor starts to fail it will allow a higher voltage to the temp/ fuel gauges that will then give a higher reading,
The other possibility is an airlock near the temperature sender unit so a good bleed to make sure you have only coolant circulating,

malcolm bell

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malcolm bell

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