Thats great advice, thankyou.
As soon as the stud is in the hole the leak stops, as it's a new engine just fitted it has been run for approx 10mins on the drive with no problems and driven home for approx a mile, again no problems. Will need to keep an eye on coolant level though.
Will the exhaust paste be waterproof though?
If I use the "bung" method any suggestions of what to use or where to get a suitable "bung"?
Thanks again