I was looking for a fun car and I came upon a 1993 SAAB 900 Turbo for $9,500. The vehicle had 135k miles and an Automatic transmission, so I am wondering if those engines are reliable.
I am wondering if those engines are reliable.
They can be. Unlike modern turbocharged vehicles Saab's Triumph-derived 4-cylinder engines are heavily built (some say over-built) with cast-iron block, forged internals, and sodium-cooled exhaust valves. The turbochargers are simple devices and not nearly as expensive as in today's cars when replacement is needed. A weak point is due to having a cast iron block and aluminum head it's pretty much a guarantee that the head gasket will blow if the engine overheats. Ditto if the cooling system is not properly maintained.
I've owned several "Classic" (original, non-GM) 900s over the last 40 years and have run them for hundreds of thousands of miles without any internal engine repairs needed. I currently have a 1986 900S with 300,000 miles and the engine still runs practically like new. Of course getting this kind of service out of one depends on proper maintenance.
Unless it was beaten to death and not maintained the engine will be the least of your problems. The transmissions are not nearly as bulletproof as the engines. The automatics are terrible and even the manual transmissions have their issues.
You say the one you're considering has an automatic trans. The automatic transmissions in these cars are horrendously bad - a front-drive variant of the 3-speed Borg-Warner type 35 or 37 transmission whose basic design dates back to Studebaker. The trans saps engine power and reduces gas mileage. Engine RPMs at freeway speed are high. Lifespan is typically 100K miles or so and at this point almost no one knows how to rebuild them. Quite a few people who own 900s with the slushbox convert them to manual transmission.
Watch out for rust. They'll rust in the area where the drive axles go through, and the rear control arms for the twist-beam rear axle are mounted under the trunk and can break free due to rust. Fender lips are susceptible to rust and the entire body is one piece - front fenders are a welded part of the structure, not bolted on.
The other issue of course is that it's a niche vehicle over 30 years old from a long-dead manufacturer. Be prepared to do some searching for parts and some may need to be ordered from overseas. Most mechanics don't know how to work on them and a lot of Saab specialists have retired or passed away. However for most things they are not difficult for the shadetree mechanic to work on.
If you do buy one you'll want to join a Saab-specific forum for technical information, such as:
https://www.saabnet.com/tsn/bb/general/
