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Discussion Starter #1
Hello,

I just checked my radiator level today and it is full to the top, but my coolant expansion tank seems empty. I can not tell for sure because it is so hard to check. Is that normal? I mean it is important for radiator to be full, I do not have any problems with heating. Temperature guide is always bellow half.

Honda fn2 type R


Thanks!
 

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Earth Dreams :)
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Easy: just fill it up with water so it's somewhere between Min and Max...
Of it was me, I would use Honda coolant and not just water.. as it mixes with your engine coolant, it will dilute it... the coolant has additives which prevent rusting, provide better cooling properties and also gives a lower freeze temp point for those winter months..
 

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Use honda coolant. a 5L ready mix isnt expensive either. If the expansion tank is empty (make sure its actually empty because theyre not the easiest to read) then make sure the radiator is full as well.
 

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regrets his username
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Between min and max when warm from memory, I think it reads pretty low on a cold check.
I made the mistake of filling it cold and when my engine was hot the level was near full, had to buy myself a fluid syringe with a long tube on it and drained it until ok
 

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Discussion Starter #8
Thank you all for help ! I already topped it with total G12 coolant. I will never put just water, I think total is good enough because it is not easy to find Honda coolant in my country.
 

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He didn't say that he had got it, just that topping up with tap water can possibly cause it, however unlikely given the amount needed for a header tank top up.

What really surprises me is that the OP needed to ask about topping up the coolant in the first place.
 

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I Hate tailgaters!
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Yep, good old fashioned tap water!
Water boils and turns to steam at 100 degrees. Coolant doesn't = another reason not to use water. I had something similar with my mk8, radiator full yet expansion looked empty. i just bought a 1 litre bottle of honda coolant and topped it up until half way between low and full. It is difficult to reach and see what levels its at. I stuck my ledlenser on the side which lit up the interior giving me a good idea of its level.
 

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Water boils and turns to steam at 100 degrees
Yeah, no it doesn't.

Dihydrogen monoxide/water/H2O

At 1 bar water boils at 99.6°C
But that is just being a bit anal.

When under a high pressure water boils at a higher temperature

At 2km above sea level which is around 0.8bar water boils at 93.4°C

When the radiator is under 1.1 bar of pressure
You would be at -700m below sea level to get the same boiling point of 102°C

But overall it is the pressure that dictates boiling point.

Now start adding other compounds into it and the boiling point changes.

Add 1oz of Sodium Chloride to water and the boiling point increases by 1°F

Not under pressure it doesn't. At 16 psi it boils at about 120C.
Best double check that.

Water boils at 120°C when at 30.5psi
 

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I Hate tailgaters!
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Yeah, no it doesn't.

Dihydrogen monoxide/water/H2O

At 1 bar water boils at 99.6°C
But that is just being a bit anal.

When under a high pressure water boils at a higher temperature

At 2km above sea level which is around 0.8bar water boils at 93.4°C

When the radiator is under 1.1 bar of pressure
You would be at -700m below sea level to get the same boiling point of 102°C

But overall it is the pressure that dictates boiling point.

Now start adding other compounds into it and the boiling point changes.

Add 1oz of Sodium Chloride to water and the boiling point increases by 1°F



Best double check that.

Water boils at 120°C when at 30.5psi


1. I stand at 100 degrees.
2. What's sea water got to do with it, he's not adding that is he.
3. The person who suggested water is from Staffordshire, England. When we get High pressure we think summers arrived but it goes after a couple of days. Usually we get low pressure front after low pressure front rolling in from those yanks.
4. As mentioned, it is a bad practice and can cause problems if you add water to your coolant diluting it. It will lower the boiling point. And if left unchecked will cause corrosion in your system.
5. It lowers the ability of your coolant to protect engine at freezing temperatures. Stafford should know we can get those after this years winter.
6. Plain old tap water is the worst offender to cause corrosion, in a desperate situation distilled water should be used. But only when engine cooled.
7. If he suspects his system is leaking coolant, check for the obvious drip signs. Re-seat or change the radiator cap incase that's misbehaving. My mk8 used to wind me up by leaving white residue around the base of the radiator cap. So I took it off, wiped it, refitted and then topped up expansion tank to midway on a cold engine. Then spent every time I lifted the hood checking around the cap with a ledlenser.

And 700m below sea level 1.1 bar. ?



Sent from my iPhone using Tapatalk
 

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At an absolute pressure of 30 psi water boils at 121C REF
As atmospheric pressure = about 15psi add 15 psi = 30 psia = 121C so I wasn't far out.
And I did say "about" as I can't be assed to do it to the nearest 0.1C

The point that I was trying, but obviously failed, to make was that the coolant in a car is much more affected by the pressure in the system than the actual coolant mix.
 
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