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Discussion Starter · #1 ·
Hello all - I recently purchased a 1997 saab 900s with 105000 miles. Before purchasing, I had a mechanic conduct an assessment of the vehicle. He pronounced it in great health except the water pump and a pulley would need to be replaced. The private owner selling the car has a mechanic friend. He offered to purchase the parts and have his friend make the replacement rather than pay the inflated cost of the non-friend mechanic who conducted the pre-purchase exam. After the repair and my subsequent purchase, there is a coolant low message being displayed. I've examined the coolant level in the reservoir and it appears quite high (it is well above the Kalt - Cold line). I drove the car for about 30 minutes the other day and the temperature remained at 9 o'clock on the temperature dash gauge. There didn't appear to be any significant coolant lost from the reservoir. I'm worried the seller's mechanic didn't attach some piping along the way, but wouldn't the temperature of the engine register much higher? I'm also concerned there is a leak some where but wouldn't there be a loss of liquid in the reservoir? A lot of older posts on this subject mention a faulty sensor. That remains my primarily culprit but I have my doubt on that as well. Why would the sensor all of a sudden stop working now after the water pump was changed. When we drove the car for 2 - 3 hours before purchasing it, there was never a low coolant level message. I'd appreciate any thoughts or expert/knowledgeable suggestions. I really don't know cars well, especially the internal workings of an engine. Any pointers are greatly appreciated. Thank you!
 

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As far as I know, the only way you can get a "coolant low" message on our cars is if the coolant really is low, or if the sensor is faulty or stuck. Make sure the coolant in the overflow tank is all the way up to the cold/kalt line... only has to be down a little bit to set the message.
 

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Discussion Starter · #3 ·
Thanks Frogdude for the reply. The coolant level is well above the Kalt-Cold line so it is pretty close to full. But if it was a leak, how fast should I expect the fluid to leave? Does it continue leaking when the engine is not on?
 

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Unless you have a really serious leak, it shouldn't leak when the engine is cold. Sounds like you have a faulty sensor, or it may just be stuck. The sensor has a little float inside the overflow tank that could be stuck in the down position. Might be worth giving the tank a small "whack" with your hand to try to dislodge it, or maybe try removing some fluid with a turkey baster and adding it back quickly...

Also, make sure the wiring is connected to the sensor properly.

Here's a link about sensor repair.
http://www.saabcentral.com/forums/showthread.php?t=184277
 

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Discussion Starter · #5 ·
Great suggestions and thanks for the sensor repair link. The only reason I thought it may not be the sensor is that the problem didn't exist before the repair. It just seems odd to me that the sensor would magically stop working once the water pump was replaced. But I agree, the sensor seems the most likely issue.
 

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It's possible that the person who fixed it dislodged the sensor. The first step would be to make sure the little electrical unit on the front-bottom of the tank is snapped in tight. Just push on it and make sure the little hook on it is snapped into the little slot that holds it in place.

The second step would be to make sure that the float is working properly and/or to clean it. To test it, the next time you start the car and the message is on, open the cap on the tank and use a short piece of coathanger to push the float against the front of the tank. If the message goes off, the problem is the float operaton. You may need an assistant to watch as you hold the float in place, but chances are it will stay there once you push it up into place - at least long enough to check the message.

If moving the float doesn't fix it, chances are that the reed switch mentioned in the previous link (above) is the culprit. Best fix then is a replacement tank from a junkyard.

If you can shut it off by fooling with the float, then you should probably clean the float and tank. That's best done by removing the tank. All you need to do is to disconnect the two hoses, pull them off, and then remove the one bolt that holds the front of the tank down. Pull the tank up off the hanger and it's out.

Go to work with some long q-tips and/or a mechanic's grabber tool with a bit of cloth on the end. Clean all around the float as well as in the other two chambers. Rinse and continue to clean until everything is out of the tank. Reinstall. If you were careful and you caught most of the old coolant on the way out when you pulled the hoses, you can resuse it... or you can add a 50/50 mix of whatever coolant is in there (tell us the color, we can tell you what to buy), or just add water if you're confident that the mixture in there is strong enough to handle a little minor dilution. If you add water, take a drive to mix it up before it gets down to freezing temps where you are.
 

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Discussion Starter · #8 ·
Thanks BobSaabit (great name) for the super detailed message. I appreciate you taking the time to reply. Your first suggestion, insure the electrical unit is snapped in, was attempted earlier and the message still remains. Its dark here now (I live in DC) so I'll try the coat hanger with the float tomorrow morning. I'm hoping that is causing the concern. When I look at the coolant reservoir, I can see some sediment build up on the inside. So maybe a cleaning would do the trick.

Again me being a novice, this may be a stupid question, but if I remove both hoses won't the coolant just continue flowing out through the hole onto the engine or ground?
 

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If you can see sediment, there's a good chance that's it.

When you first pull the hoses some coolant will run out which you can catch in a container. You can either stick something in the hoses like large bolts, or you can just twist them so that the ends are sticking up higher than the radiator and they won't drip much.
 
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