If the cylinder heads have been removed for any reason, it's not a good idea to reinstall the old pushrod tubes, as the risk of leakage is very high.
Volkswagen claims that this is possible, but only if the pushrod tubes are still in perfect condition, which is not the case in 99% of engines.
Rust affects the tubes to such an extent that a permanent seal can no longer be guaranteed. You can only reuse them if they have little or no corrosion. In this case, you'll have to remove the harmonica part slightly, as they have to be mounted under slight tension.
Standard pushrod tubes, like the original, are not treated, which explains why they rust so quickly. To get rid of rust for good, it's best to opt for stainless steel. Some motors are even available only in stainless steel. This isn't how your Volkswagen left the factory back in the day, but they're still neat and tidy, and you can reuse them after tearing them out slightly if necessary.
Installation tip : Make sure the welds face upwards, to avoid leaks.
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