On the heat exchangers of all Type 4 engines mounted in the Volkswagen Bay Window Buses, an air duct inspection cover is mounted to access the cooling air valve mounted in the fan shroud.
This valve ensures that the cooling air can only exit the fan shroud. If a fan is fitted and this valve is not present, heated air from the engine compartment is used to cool the engine, cooling is then done with hot air and this is fatal for an air cooled engine, the cooling air must be drawn in as cold as possible, or from outside.
Not all Type 4 engines are equipped with an additional fan from the factory, in which case these valves are of little use but are standard on these engines. The Volkswagen 411 and 412 had a standard fan at the time and the same engine was later used for the VW Bay Window Bus, so they are there and sometimes have no use.
If the heat exchanger needs to be replaced due to rust, in many cases the inspection cover has also done its time and needs to be replaced.
Don't forget to order the gasket as well, our inspection covers are identical to the 1973 Volkswagen revision, which used a loose gasket instead of one built into the cover.
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