Saab's history has had its high and low points over the years; for certain the company had its fair share of wacky ideas that fell with dull thuds with consumers. But Saab's greatest legacy is that for every iron bomb it dropped, it wrote one pure symphony of genius and design. The original Saab 900 turbo wasn't just the most legendary car the company ever built -- it was a true legend in its own right.
The Saab H-engine's thermostat is in much the same place as it is on most other engines: the thermostat housing, where the upper radiator hose connects to the engine. The thermostat housing on this engine is a bit difficult to get to compared to that on most other four cylinders, because it's on the back of the transverse engine, facing the firewall. In order to get to the thermostat housing, you'll need to remove the idle air control valve, which is held by a bracket bolted to the thermostat housing. Once you get to the housing, remove the two 12 mm bolts, clean the surface, and use a new sealing ring to reinstall. Tighten both bolts to 6 foot-pounds, and top the system up with a 50/50 GM Dexcool and purified water mix.
While you're in there, you might seriously consider either snugging down or replacing the hose clamps on the three hoses connected to the water pump. These hoses are notorious for leaking if not tightened down as a part of regular vehicle maintenance.
