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Is my antifreeze trying to tell me something


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Evening all. 

Sorry if this is an elementary question, but i've done about 700 miles since a cylinder head refresh on my mk3 Spitfire, and notice that my glycol-based coolant abruptly changed from a pleasing blue to a dull dishwater within the last 200 miles. The overflow bottle is still bright blue, not that that means anything.

Is this a sign of trouble, or just that the rust in the block has worked its way in after a few heat cycles?

It had a new rad and alloy waterpump housing in conjunction with the head work, but the block didn't have any attention.

Suppose I'm concerned it's a sign of impending head gasket failure or something equally undesirable. I have re-torqued the head 3 times since getting it all back together. No other obvious signs, the water doesn't look particularly oily.

Any reassurance gratefully received!

Pete

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7 minutes ago, Sprint95m said:

Did you drain all of the coolant from the block when you had the cylinder head removed?

Hi Ian,

Yeah, certainly did. Block stayed in the car though so there will have been a bit left in somewhere no doubt. 

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Fairly typical I reckon.....  and likely inevitable unless the radiator is new and all other parts have been chemically cleaned.

In fact it looks rather better than Chris's Spit, whose capacity for turning clean water or coolant into evil black gunge is "impressive".   We flushed it several times when it was first commissioned with limited success and gave up.  When the cooling systems was dismantled during the EFI conversion last summer we had another go, including a couple of goes with washing soda and that did seem to work for a while, but when we had it apart again to do the the head gasket it was pretty black again so it was again flushed several times.  This evening, maybe 300 miles on, it's black again.

We have tended to point the finger at the used Golf GTI radiator which had possibly it came from a car that had had oil cooler failure (many did)...... and initially that may have been true.  Now it's actually probably coming from the block water jacket as the discolourant is fine black, slightly magnetic particles.

GT6 is playing similar games, though on a much lesser scale as that has a new radiator and the block (ex-Vitesse) has been in use for most of it's existance and with proper coolant for the last 30 years.

 

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Thanks Nick, that's the kind of reassurance I was looking for :)

It was a newly re-cored rad, and I was taking great pleasure in the pristine blue coolant every time I checked levels. But then like I said, it seemed to abruptly turn dull grey. Noticed after it's longest voyage since the work - 150ish miles of high revving on a hot day.

The astronomical oil consumption of that journey, coupled with the RBRR postponement, mean it'll be having a re-bore in the near future if I can scrape funds together. But I need it for some mileage transporting children around in the next couple of weeks. 

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Guys, have you checked your hoses as well?

Antifreeze/coolant is vicious stuff on the quiet (try putting some neat onto a painted surface and leave it!!), so I always keep an eye on hoses etc.

Not trying to suggest this is the problem (and if you use silicon hoses this should be less of an issue), just a heads up in general.

Phil

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Holts make a two-part cleaner called 'Radiator Revitaliser' and I suspect there are other similar products. I have used the Holts system in the past and it does seem to shift some of the muck. Might be worth a try when you next change the coolant.

Ian

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Hi,

 Black is normally Iron Oxide from corrosion of Iron. It is magnetic. A high temperature magnet in the header will capture some.
Morris Corrosion inhibitor at 2% will help.

Cheers,

Iain.

Edited by spitfire6
https://www.premierlubricants.co.uk/autosport/specialities/morris-ankorsol-anti-corrosion-fluid.html
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Thanks Iain. I assumed the anti-freeze would be sufficient for inhibiting corrosion but maybe my ratio was too weak.

Having done some longer distances now she seems to be running a touch warmer than with the old radiator, although I replaced the thermostat as well so more likely that's the reason.

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We're used to seeing Iron (III) oxide, ferric oxide, Fe2O3, as the red rust we are so familiar with.  

But Iron can form other oxides, in particular iron (II) oxide, ferrous oxide, FeO, which occurs when there is a relative lack of oxygen.   It has a deep black colour, so that's what you're seeing, as all the oxygen dissolved in the water you added is used up.

John

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48 minutes ago, JohnD said:

iron (II) oxide, ferrous oxide, FeO, which occurs when there is a relative lack of oxygen.   It has a deep black colour, 

John

That is the stuff which sits in the bottom of old household radiators, and new ones if no inhibitors are added to the system. Stains cream carpets beautifully, ask me how I know:blink:.

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5 hours ago, John I said:

That is the stuff which sits in the bottom of old household radiators, and new ones if no inhibitors are added to the system. Stains cream carpets beautifully, ask me how I know:blink:.

Oh yeah! No cream carpets here mind - we are much too grubby for those!

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On 21 August 2020 at 9:35 PM, Nick Jones said:

Oh yeah! No cream carpets here mind - we are much too grubby for those!

None in our house either, me and the dog far too messy.

It was a clients house. I sheeted out everything but an area about 2ft square.......and that where the mucky water landed :wacko: Live and learn.

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