MX5 Fisher Fury build diary

Went down with Alistair with the hope of doing some work and him having a drive. We tidied up a few earths first then started the engine which ran smoothly at first but then an odd lumpiness / misfire like the second run last week which I had put down to the very wet conditions. Then Alistair noticed steam coming from the plug lead area of spark plug 4. Drew the plug leads and found water swimming round the plugs of 1 & 4. A was very concerned, although I thought it was just condensation. Also noticed milky white inside oil filler cap which was not there before. Wondered if we had an airlock (did not want to think about cracked head). Released the cap on the expansion tank, which was bung full, and water flooded out so we let a bit more out and ran the engine with no cap on the expansion tank. There is no expansion outlet in the system I've installed and I had not thought about a pressure relief cap anywhere. The aluminium cylinder head has water cooling and we think that the pressure must have been pushing it out into the rocker cover and hence into the spark plug recess. There must have been air in the system too because as we ran it the level dropped and I had to add a litre of water before it stabilised. Now the engine ran sweetly, and idled fairly smoothly. The fan soon started to cut in and out as needed and all seems well - the milkiness even dissipated from the oil filler cap. There is a slight weep on an old rubber water pipe I have not replaced at the idle control valve and a fuel leak at the injector on 1 - I cannot have seated it correctly but that's easy to do.

Need to find a water pressure relief method.

Then I drilled the vent holes in the ends of the exhaust pod for extra cooling while Alistair fitted spiral wrap around some cables. Nev has started re-doing the bonnet and he is going up to Evesham to collect a non-runner MX5 Alistair has bought.

Delicious day today.