Nodge68
Well-Known Member
Td4 has a plastic thermost housing too, sealed with an o ring. ..mines now got a new o ring and gasket sealer for extra strength. ... theres another plastic bit stuck to the head which has also got new o ring and huge dollops of gasket sealer on it too......and its fixed.
In 20k id have to do this again on a k series![]()
BMW do love there cheap plastic bits bolted to metal.
O rings simply aren't designed to last forever like a proper metal housing with a gasket.
From what I've seen over the years, these plastic bits fail long before the engine. However it's often the failed plastic bits that cause the engine to fail.
Lots of manufacturers use plastic for thermostat housings, top hose connections, cam covers and the like. The downside is, plastic has a short life in the engine bay environment.