In the case of an original steel sliding roof, water that may enter through the edges is drained off by means of pipes. On the Volkswagen Bay Window Bus and its successor, the VW Vanagon, rubber valves are mounted at the end of the hoses to ensure a good seal on the bodywork and also allow water to drain off, as splashes have no chance to penetrate. If you own a Volkswagen Bay Window Bus, you will need four and for a VW Vanagon, you will need two in case you need to replace them all.
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