Chain tensioner replacement on air-cooled 911s,dont wait

The timing chain tensioners on air-cooled 911s are the Achilles heel of the engine. There are two, one per bank, and they're spring-loaded with a hydraulic assist. When they fail the chain goes slack, skips teeth, and the engine is destroyed. Early tensioners with the rubber pad are the worst offenders. Upgrade to the Carrera-style update tensioners or the aftermarket LN Engineering units. About $400 for the pair. If you hear a rattle on cold start that goes away after a few seconds, that's the tensioner not pumping up fast enough. Get them done immediately.