PeteStupps Posted August 12, 2020 Share Posted August 12, 2020 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 Link to comment Share on other sites More sharing options...
Sprint95m Posted August 12, 2020 Share Posted August 12, 2020 Did you drain all of the coolant from the block when you had the cylinder head removed? Ian. Link to comment Share on other sites More sharing options...
PeteStupps Posted August 12, 2020 Author Share Posted August 12, 2020 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. Link to comment Share on other sites More sharing options...
Nick Jones Posted August 12, 2020 Share Posted August 12, 2020 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. Link to comment Share on other sites More sharing options...
PeteStupps Posted August 12, 2020 Author Share Posted August 12, 2020 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. Link to comment Share on other sites More sharing options...
thebrookster Posted August 13, 2020 Share Posted August 13, 2020 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 1 Link to comment Share on other sites More sharing options...
Gt64fun Posted August 13, 2020 Share Posted August 13, 2020 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 Link to comment Share on other sites More sharing options...
spitfire6 Posted August 20, 2020 Share Posted August 20, 2020 (edited) 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 August 20, 2020 by spitfire6 https://www.premierlubricants.co.uk/autosport/specialities/morris-ankorsol-anti-corrosion-fluid.html Link to comment Share on other sites More sharing options...
PeteStupps Posted August 21, 2020 Author Share Posted August 21, 2020 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. Link to comment Share on other sites More sharing options...
JohnD Posted August 21, 2020 Share Posted August 21, 2020 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 1 Link to comment Share on other sites More sharing options...
John I Posted August 21, 2020 Share Posted August 21, 2020 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. 1 Link to comment Share on other sites More sharing options...
JohnD Posted August 21, 2020 Share Posted August 21, 2020 It is described as a useful, black dye! Link to comment Share on other sites More sharing options...
Nick Jones Posted August 21, 2020 Share Posted August 21, 2020 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. Oh yeah! No cream carpets here mind - we are much too grubby for those! Link to comment Share on other sites More sharing options...
John I Posted August 27, 2020 Share Posted August 27, 2020 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 Live and learn. Link to comment Share on other sites More sharing options...
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