Thanks to Troy Lamoreaux for contributing to this FAQ!
A friend gave me his 900 S. After 14 years it needed some work and his wife just didn't want him to spend any more money on it. I recently replaced the head gasket and it runs good now. However I believe that it is time replace the timing chain. The tensioner is measering at 20mm and the guides are worn. I wish I would have done the timing chain at the same time as the head gasket but I needed to find out if it would run. The guide below is an example of the wear on the guide.
Guide wear as seen in the picture above typically comes from chain slap. We have seen issues where guides get worn from the engine overheating causing the guide material to soften up increase the speed at which a guide wears but in the case shown above it is doubtful that heat caused this. On the 900 1979-1994 Saab 900 guide wear comes from the timing chain tensioner wearing out which leads to the chain slapping the guide causing grooves like are shown this picture. Replace of the tensioner and guide is the cure.
Pricing for 900 79-94 ENGINE TIMING COMPONENTS 16V (engine timing components)
Pricing for 900 79-94 TIMING CHAIN COMPONENTS (engine timing components)
Pricing for 900 79-94 TIMING CHAIN COMPONENTS 8V 79-80 (engine timing components)
Pricing for 900 79-94 TIMING CHAIN COMPONENTS 8V 81-88 (engine timing components)
Pricing for 99 TIMING CHAIN COMPONENTS (engine timing components)
Pricing for 99 TIMING CHAIN COMPONENTS 8V 79-80 (engine timing components)
Pricing for 99 TIMING CHAIN COMPONENTS 8V 81-88 (engine timing components)
