Cooling system on S11 4.2 roadster (1970)

[Simon123]

Hi there

I have recently acquired the above and hopefully someone can help me with some advice. I had a little problem being that the drive belt bust to the water pump, which caused engine to overheat spitting out some coolant, I stopped immeadiately and hopefully no damage was done. My question is that on reading the orginal manual about engine cooling it made reference to expansion tank which is pressurised, and radiator is not, also it mentioned top up should be at tank not radiator, also it mentioned that caps should not be mixed up, I found cap to radiator had spring on it and one to tank did not, I think cap with spring on it should be for the pressurised expansionn tank, can anyone help me with the answer please?

Thanks,


Simon Couldridge.

[christopher storey]

I think it very unlikely that you will have done any damage, since you stopped immediately. On my S2, if having to refill after a substantial loss of coolant , I always fill the radiator first, despite what it says in the book, as I found that airlocks can be a problem. Then, having circulated coolant round the system by running the engine with the rad cap off for 2 or 3 minutes, and ensured that the radiator is not airlocked, I replace the unpressurised cap which as you say should have no spring on it , and then fill the expansion tank to the half way mark and put the pressure cap on that. The pressure cap should have a marking on it, probably either 4 lbs or 7 lbs although some people do fit 13 lbs ones which I regard as unnecessary at our temperatures and altitudes