The 24-valve VR6 (Mk4-era R32/VR6) has an infamous coolant weak point: a plastic coolant crossover pipe that runs underneath the intake manifold and becomes brittle with heat and age, then cracks — the legendary "crack pipe". It leaks coolant in the valley of the engine where you can't see it, and getting to it means removing the intake manifold. See VR6 Timing Chains for the other big VR6 job
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