Originally Posted by Caddyshack

Here is an odd issue: when Mark Shead had the car he noticed that the cooling system was pressurising to the point of splitting the metal expansion tank. I found that the coolant cap had no pressure relief so added that. As a precaution I went over to Evans waterless as that doesn't expand. I flushed it through with the prep fluid and then filled with waterless.

Today I went for a blast and gave it some full throttle up to about 6000 rpm in 3rd (God does it fly) and when I got back the cap was steaming and the coolant expanded out of the tank. When I removed the cap it pumped out some fluid. Now if the Evans doesn't expand I wonder if the head is lifting under boost and pressurising the system? Mark did say it could be this before.

I guess the thing to do it to have a new expansion made by spec r with a good relief valve and do some testing before I resort to a rebuild with long studs and better head gasket etc.

I am trying to hold off the engine rebuild as want to get some miles on the car to sort other niggles and this will give me more time to decide on long stroke or not as that is a whole other heap of money.