VW blessed these engines with not one, but two plastic coolant parts sitting right where heat, pressure, age, and bad decisions can do their best work. One is the factory coolant flange. The other is the bypass valve: a fiddly little plastic science project full of moving parts. Both work fine until they do exactly what old plastic does under the hood: crack, swell, warp, leak, and ruin your day.

This kit deletes that problem twice.

You get both billet 6061-T6 aluminum replacements in one package: the coolant flange and the sealed bypass valve flange. No brittle plastic bodies. No failure-prone valve guts. No warped sealing surfaces. No mystery coolant smell. No puddle appearing right when you were already late.

The coolant flange replaces the weak factory plastic flange with a solid billet piece built to hold shape, seal properly, and survive heat cycles without turning into garbage. The bypass valve flange replaces the overcomplicated factory valve with a sealed, no-moving-parts solution that closes the loop cleanly and permanently.

Run them on a stock engine.

Note, on a non EGR deleted engine without a tune, this will cause a P125A00 or similar CEL, as the ECU notices that the difference between temperature of coolant at engine outlet and temperature of cylinder head is less than 5 °C (9 °F). It is recommended to tune it out by a tuner, but you can run it without issue untuned. The CEL might be annoying.

Both parts are machined from solid 6061-T6 billet aluminum and use genuine VW/Audi seals, because the sealing surfaces matter and cheap rubber has no business living in your coolant system.

Two parts. One fix. Less plastic. Fewer leaks. More not-being-stranded.