KatnDougal wrote: Questions:
At what level should expansion tank be when hot, should it go down to half and be half liquid/half air?
And should it refill again when cold?
The left hand tank should ALWAYS be 100% full.
The right hand "top up tank" should be between the marks when cold (about 1/3 full).
It should only get fuller than that when the whole motor etc is good and hot, when the system is cooling down, some water from the top up tank gets sucked back into the expansion tank to keep it 100% full.
KatnDougal wrote:At what point should fan kick in under load?
Could it be a wiring issue?
Load has nowt to do with when it kicks in, it is purely on temperature.
Not sure what temp the thermo switch kicks in - someone will come along and tell us

Yes it could be a wiring issue.
My fan does not come on very often at all, mostly only when sitting in traffic or when I am doing it on purpose by letting it tick over on the driveway for 30 minutes or more, then it will come on (due to no air flowing through the rad fins.)
it should always be full, this indicates you may still have an airlock in the system (imho of course)KatnDougal wrote:p.s. only when i release the pressure off the dalek cap (when cold) does the expansion tank fill up to the brim with water again...
KatnDougal wrote: p.p.s i have just noticed a drip coming from the large rubber seal around the right side of the engine block - is it the water jacket seal and will these cause me problems?
This could be serious I am afraid.
I suspect your seal was less than perfect due to age etc and the excess pressure you experienced has damaged it further by forcing water past it.
See this thread here for more on this subject (it is a long thread but deffo worth reading) =
https://club8090.co.uk/forum/viewtopic.php?f=37&t=52374" onclick="window.open(this.href);return false;