Overheating problem Temp gauge reads over heating, but air coming from heater matrix is cold, water in rad expansion tank, and water coming from bleed points in rad and heater matrix pipes on bulk head. Water from heater matrix bleed point exits with some force so system is under pressure. If revs held at 2000rpm heaters blow hot and temp gauge drops, but if on tick over heater blows cold and temp gauge goes up until "STOP" light comes on. Having really bad time with this, was thinking water pump but not sure. Any help will be greatly received.

Could be that the thermostat has packed up...

Check all your coolant levels are correct and then take her for a good run out....keep your eyes on the temperature gauge,,if your temp gauge hardly moves then your thermostat is at fault....replace it.

If temp gauge works fine, you may be airlocked in your heater matrix... Try setting heater to full heat with fan on full power,, whilst car is ticking over, remove radiator / expansion bottle cap carefully and start squeezing your coolant pipes. This should force any air out through your rad/bottle top..

Please be aware that as your temperature rises in the engine. Your coolant will expand and start to flow out of the rad/expansion bottle..at this stage quickly replace the cap....check your heater...leave engine to cool....unscrew rad/bottle cap, check coolant levels, top up if necessary and squeeze pipes again..start car with heater/fan on full and repeat above.....

Hope this helps..

full flush it yet. (AF change out is very limited)
rad tubes clogged, use pyro gun to find this easy.
bad pump. all AF goes acid if IGNORED.
fan belt slips.
Rad fans dead.
thermostat upside down
thermostat bleed hole not up hill , trapping air in block making gauge fail too.
is the block really full of AF or are you reading the liar tank, onside.
check rad levels in the RAD cap neck for full or not. dead cold.

is it is really overheating or only the fibbing gauge , tells you that,?
no steam?
no bursting of AF out side tank
no pinging,?
no loss of power.?
lots and lots of signs , not one stated.......do so please.
A/C trips off line? (it too has over heat detection)

when the gauges are telling you that a problem exists like over heating. Cold air may mean an air lock in the cooling system. So I consider it to be foolish to risk a motor without checking the temp gauge for correct operation for starters . After running for 10 minutes feel the top radiator hose and if it is not hot to the touch but the gauge shows hot then you have a cooling system problem that would be checked by a radiator shop.. It may just need pressure bleeding to get the air out of the system

CHECK COOLANT FAN FUSES AND RELAYS. CHECK COOLANT LEVEL.MAKE SURE ITS NOT TOO LOW BECAUSE IF COOLANT TOO LOW . BY NO COOLANT AROUND OR COOLANT SENSOR NOT SUBMERGED IN COOLANT COOLING FANS WONT TURN ON.MAKE SURE YOU HAVE 50/50 ANTIFREEZE AND WATER. CHECK FOR CLAPSE RADIATOR HOSES.CHECK RADIATOR HOSE AT WATER PUMP.IF HOSE LOOK CLAPSE REPLACE IT AND BLEED COOLANT SYSTEM.IF EVERY THING HAS BEEN DONE YOU NEED ENGINE BLOCK FLUSHED OUT.HEATER CORE ALSO COULD BE STOPPED UP.A VERY HIGH MILEAGE ENGINE WILL OVER HEAT.OLD ENGINE LOSES COMPRESSION AND HORSE POWER.PUTTING MORE LOAD ON THE OLD ENGINE WILL MAKE IT OVER HEAT.IF COOLANT LEVEL IS LOW.BLEED COOLANT SYSTEM.START THE ENGINE LET IT IDLE FEW MINUTES WATCH THE COOLANT TEMPERATURE GAUGE.WHEN TEMPERATURE START RISING.TURN OFF THE ENGINE LET IT SET FOR 20 MINUTES.TAKE A LARGE RAG PLACE OVER RADIATOR CAP ON COOLANT EXPANSION TANK SLOWLY OPEN RADIATOR CAP JUST A LITTLE TO RELEASE A LITTLE PRESSURE AT A TIME.DONT OPEN CAP RAPIDLY OR YOU WILL GET SCALDED.ONCE THE RADIATOR CAP REMOVED.IF COOLANT LOW ADD MORE COOLANT IN THE THE COOLANT EXPANSION UNTIL YOU GET TO THE COLD MARK.REPEAT THIS PROCEDURE START ENGINE LET IT RUN UNTIL TEMP GAUGE START CLIMBING A BIT DONT LET CAR RUN TO OVER HEAT JUST IDLE UNTIL TEMP JUST START TO RISE.THEN YOU TURN OFF ENGINE. WAIT 20 MINUTES.THEN USE LARGE RAG OPEN RADIATOR CAP LITTLE AT A TIME. DO THIS PROCEDURE UNTIL THE COOLANT IN THE EXPANSION TANK STOP DROPPING. THEN ALL THE AIR IS BLEED OUT THE COOLANT.WHEN COOLANT LEVEL STOP DROPPING, WHEN YOU DRIVE CAR AROUND.AND TURN OFF ENGINE.WHEN ENGINE OFF CAR SET FOR A WHILE KEEP CHECK ON THE COOLANT LEVEL IN COOLANT EXPANSION TANK. THE COOLANT LEVEL SHOULD BE AT THE COLD MARK IN THE EXPANSION TANK.MAKE SURE COOLANT IS IN THE EXPANSION TANK.IF NOT AIR WILL DRAW IN COOLANT SYSTEM. CAUSING ENGINE TO OVER HEAT.IF BLEEDING AIR OUT THE COOLANT SYSTEM DONT HELP AND COOLANT FANS DONT TURN ON YOU HAVE PCM PROBLEMS.

Does the engine actually warm up enough to produce hot air thru the heater? In other words, does the radiator get hot to the touch? Does your temperature gauge on the dash indicate a normal operating temperature , or does it show cold? Make sure the linkage from the temperature selector in the dash is connected to the water control valve for the heater.

My guess would be the engine is indeed warming up, but a faulty (or disconnected) water control valve to the heater is preventing heated water from ever reaching the heater core.

your car is cooking!!!! if your heater starts to blow cold air its got an air lock in the system and need to be blead out to get this air out of the water jaket in the engine sounds like your gauge is working fine to me, its screeming at you to stop! as its over heating the engine, look under your hood for the water hoses you should find a hose with a kind of nut or screw in it at the higest point on a water hose, this is the bleed point, fill the rad up with water and turn on the heater to hot only do this when the engine is COLD undo this screw or nut start the engine up and watch the water flow out this bleed point till there is no more air coming out with the water, keep the rad full of water and you dont need to put the rad cap back on till the air has been bled out but keep the rad full of water all the time after all the air is out refill the rad or top it up put the cap back on and run the motor it should not show as hot as it was and the heater should work just fine

USE A RAD FLUSH SOLUTION OR CHECK THE HEIGHT OF THE HEATER MATRIX IN THE CAB , IF ITS HIGHER THAN THE FILLER/EXPANSION TANK. THEN ITS AN AIR LOCK, LOOK FOR THE HIGHEST PIPE AND SEE IF THERE IS A BLEED VALVE, IF NOT TAKE BOTH PIPES OFF THE MATRIX FEEDS AND FLUSH OUT TO SEE IF IT IS BLOCKED, AND RECONNECT LOWEST PIPE FIRST AND FILL SYSTYM TILL WATER APPEAR FROM TOP AND RECONNECT RUN MOTOR, AND KEEP TOPIN UP

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
   

it may have a blown head gasket if it keep over heating or there could be just an air lock in the cooling water,, you will need to bleed the air out to stop the over heat as the water is not going around the engine its not opening the thermostat so it cant bleed its self take off a water pipe thats the higest pipe you can find it may have a bleed vent in a pipe were you can bleed it from ,,,top up the rad and header tank take off the bleed nippel when water with no air is coming out and the jobs a good un? run the motor for a time or go for a drive to check its not ever heating again and the heater should by now be blowing hot air,, top up the rad and header tank when its coold down

Hi,
Not too familiar with this model but.... First some questions! Has the fault started after the pipes & rad replaced or were they replaced to remedy problem? If fault happened since work then i'd suggest an air lock in the system in which case you will need to 'bleed' the system of air. Make sure the expansion tank is the highest point & look for any bleed valves on the hoses - usually near the heater matrix. Sometimes it may be necessary to help the process by removing the temperature guage sender unit to allow the air to escape as air cannot pass through a closed thermostat. If the fault was there before, does the expansion tank seem to build up pressure very quickly? Do lots of air bubbles appear with the engine running & the pressure cap off?