I am just about at my wit's end!! In restoring my '83 245 Turbo, I put new front seals in the engine, new water pump, new timing belt, and converted to intercooler. Now the water is seeming to boil in the reservoir when I turn the engine off. I thought maybe air was getting into the system someway, but can't see any signs of it. There are no leaks anywhere. The water temperature is good. I have replaced the thermostat and changed the cap on the reservoir. It was another used cap though. I have searched and searched for some possible solution. I understand that a crack in the head or block could cause this, but I see no signs of this. It only started doing this after I put the intercooler in. In doing this, I did have to change the reservoir tanks (from the large boxy one to the smaller round one). Also, what ratio of water and anti-freeze is recommended? I thought maybe that would make a difference since the anti-freeze would raise the boiling temperature. Thanks for any ideas!!