2000 9-5 wagon 2.3L turbo. trouble light comes on and engine temp gauge goes high after about 5 miles of driving (winter with heat on). coolant level full; overflow tank backing up. could it be stuck thermostat or water pump? how can you tell if it's one or the other? [email protected]

SOURCE: Saab 9-3 turbo problem!

Sounds like the recirculation valve (aka diverter valve) is failing. A lot of turbo cars that have them end up with failures from them, since they're usually cheaply made from plastic, and the diaphragms inside don't hold up over time.

What the valve does is, when you shift, there is a backsurge of boost air that hits the closed throttle plate. The diverter valve (DV) opens and dumps the air back into the intake piping. It's kept closed during acceleration by spring and manifold pressure. When you shift, the pressure drops on the backside of the valve and it opens, venting the excess boost air. If your valve is failing, just the pressure of boost in the intake piping could be pushing it open, causing the acceleration to slow. I'd look into a replacement diverter/recirculation valve.

SOURCE: Saab 9-5 Aero Wagon 2000 wont restart when warm or after running

I have a 1999 Saab 9-5. I had a similiar problem. The car would always run cold. It would get hot and the engine would quit. It could be anywhere. One mile from start to 50 miles from start. Once it cooled down it would re-start but the cool down time was always different. Only difference for me was my car would crank, just not run. Replaced the crank position sensor ($60), no more problems! Good luck!

SOURCE: my saab 9-5 wagon wont start

water temp switch faulty.

SOURCE: engine overheating

the problem is your water pump some have a plastic impeller that brakes up which stop the water serculating around the engine thats what causes the engine to overheat. when you replace it make suer the impeller is alloy and change the thermastat has well just to be on the safe side. if its blowing out gray smoke the head gasket needs replacing as well

SOURCE: My 92 Saab 900 blows cold air constantly and the

Unless you have symptoms of over-heating, I rather doubt that your water pump is a problem. I recall that my water pump had a metal impeller (1992 C900); I haven't heard of a plastic impeller on a Saab pump before. (Most pump failures are the bearing seal, and the pump leaks coolant) If your temp gauge is slightly low (and was OK before) I'd rule out water pump issues.

You might have one or more of the following issues:

1. did you use a Saab thermostat? The Saab stat has three stages (no flow to rad - cold; flow to rad and heater core - normal operation; and no flow to heater core, full flow to rad - overheating) that most after market stats don't.
2. did you use a low temp stat? this opens at about 82 deg (rather than 89 deg), and will run cooler during the winter, hence you gauge will show lower than the mid point. The big benefit is that your engine won't overheat during the summer (a very good thing!) with the low temp stat.
3. has your rad and heater core been flushed recently? If the heater core is obstructed flow will be reduced and the heater will run cool. Feel the rad and heater hoses when your engine is warm; if heater hose is much cooler than rad hose with heater temp set to max, then core flow is likely restricted, or valve is not moving much from the shut position.
4. is you vacuum tank properly connected and are there no leaks in the vacuum piping? The tank is in the driver side rear wheel well below the trunk deck on a convertible, and in the passenger side front fender area on the other cars. It's a white bottle with one or two hoses connected to it. If not properly on, your vacuum operated heater flaps won't move. Does the air distribution knob make sucking or hissing noises when you set it to different positions? If not, check the tank connections, look for vacuum line leaks, then suspect the vacuum valve behind the distribution knob.
5. Lastly, the shaft connecting the temp control knob to the valve behind it may not be properly in place. This can be inspected, and adjusted if necessary, from the speaker/vent cutout on top of the dash. Make sure you re-connect the black flex hose to the air vent tube, or you'll get no defrosting afterwards!
6. remember, the centre vents always blow cold air; a brilliant idea from Saab so the driver (and passenger) can get fresh air in the face and stay awake while the rest of the driver, passenger and car is toasty!
7. see http://townsendimports.com/Web/cooling_system_folder/thermostatreplacement.htm for flushing and stat replacement info