I'd like to share my knowledge of the air cooled VW's. I am currently working on an 81 Westy and have just installed a new engine. The cooling system on these vans was well engineered and must be returned to the factory specs in every way. The cooling tins must all be there ( the bottom ones too!), and the thermostat must be working and in place. Freddyray had a question about the Thermostat being full cool or full hot. The Thermostat will fail in the full cool position. When it fails, the bellows extends from the spring pressure and it goes to the full cool position. This will also occur if the cable breaks. To check your Thermostat, remove it from the van and place it in water about 90C or about 200F. It should extend to about 46mm. If it doesn't go that far, it is no good. Awesome Powdercoat has started making Thermostats again. Type 4 two liter engines require the 85C to 90C ones which is why retrofitting a beetle or Mexican star won't work. The bottom tins also need to be in place so the air around the stat warms it up in good time and it will begin to do its thing. Also remember that equally important is the engine air seal which separates the cooling air from the warmed engine air. I also recommend torquing the heads again after a rebuild. Bring the engine up to temp and let it cool. This step requires removing the engine etc unless you do what I suggest: using a hole saw put two 7/8" holes and one 1" hole in the Center and both sides of the upper tins to access the upper head studs with the engine in place. You will need six grommets to plug these holes afterwards but they will save you hours of time. I think this step is a good check to ensure your heads remain tight and do not blow by. Remember, the cooling system on your van MUST be 100%! Do not cut corners, this is why people are having problems with their air cooled buses. Good luck.. I am just waiting on my Awesome Powdercoat Thermostat and ill be camping soon!! Cheers, Rob