I have an '85 Westfalia with the stock 1.9 WBX engine.  The engine has been recently rebuilt.( about 3000 kilometers ago) Everything has been working great until yesterday when I found a puddle of coolant on the garage floor.  After a bit of looking I found the leak.  The thick rubber gasket between the right head and the water jacket was torn and one end was sticking out.  What may have caused this to happen?  I was driving the van yesterday and the day before, the temperature has been over 30 Celsius (near 100 F).  The temperature gauge has been reading normal (near the led).  There is still coolant in the overflow bottle.  Is there a reason that there may have been to much pressure in the coolant system, or is it possible that the part of the gasket that popped out was not properly sealed when the engine was being re-assembled?
I will be talking to the shop that re-built the motor on Monday.  Any ideas will be welcome.
Thanks,
George
'85 Westfalia