.
If you use descaler/rust remover be aware that the core plugs can leak shortly afterwards.Failure of one of these is not ideal.Steve..
I've used the CLR on some pretty rust blocks and never had that as an issue, however, yes, it is possible for sure, but only if the plugs are rusty and going to leak anyway.
Hi again folks, I'm still battling this 'overheating' thing and I don't think it is overheating at all. I got a new digital thermometer & I tested it out on a pan of boiling water & it read sort of between 95º and 109º (centigrade that is), you know how they bounce about without a definitive reading. OK, so I ran the Mini up to 'operating' temperature & checked the temp on all the cylinders on the head near the spark plugs & it was reading somewhere near 80º, I left the rad cap off & water was flowing out of the overflow at a fair rate of knots, I run it like that for ten minutes & it lost a litre of water. When I finally stopped the motor, the rad was still looked full! I left it to cool & sure enough the level in the rad went down to the tune of around 1 litre (that's a lot). Now please tell me I'm not losing the plot, Am I too old for this? I've had Minis all through the seventies through to the eighties & then my daughters had them into the nineties & I've never come across anything like this......it's weird. Is it possible to have an airlock? I've not heard of this before, but I'm clutching at straws! Somebody out there must have come across this before! I always found that Minis were always simple to work on, especially the standard 850s with HS2 carbs, totally without modification ( except electronic dizzy). The engine is in fantastic nick with beautifully unmarked bores, totally flat head & top of block, oil pressure is at around 90 even when it gets as hot as it suggests! I think I need a new water temp gauge as it goes straight over the H limit as soon as it has warmed up......that doesn't help. So, come on guys, get your thinking caps on! Cheers!
It's a bit difficult with an IR gun to get some good places to taking readings from. I find the end of the head, next to no. 4 cylinder a good place as well as the thermostat housing and top tank of the radiator, though the latter is really only effective if you have a header tank so that the radiator is full all the time.
That brings me to something I often overlook with Minis. Most don't have a separate header tank, our Mokes have them and as a matter of course, I've always fitted them to my Minis. Given what you have found here, I cant say with certainty, but I think fitting one would make the world of difference to yours, but, only if the cooling system is otherwise clean and in good order. Having a header tank, among other things, keeps air out of the system and reduces or eliminates the ability for rust to start forming in the cooling system.
If you have a heater then yes, you can get an airlock for sure and a header tank here can help no end.
