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Discussion Starter · #1 ·
So I've been having some issues with my Saab, got about 105k miles on it.

Two times lately after idling (while in drive) in hotter than usual weather my car has started smoking from under the hood. The first time I got it home and there was coolant spraying/hissing out of the hose that connects to the the top left part of the coolant reservoir.

At the time I figured the clamp wasn't on right so after it finally cooled down and stopped spewing I retightened that and didn't think much of it.

Well on Friday I was coming home from work and got stuck in a drive through for at least 10-15 minutes. It was also 95+ degrees out. I didn't notice any smoking develop at the time but when I got the car home a few minutes after and parked it some massive smoke started. I popped the hood and the coolant reservoir was going nuts bubbling out from under the cap and spraying all over the engine. I threw some towels over it to dampen it and keep from getting burned. I also started seeing a pretty significant puddle forming underneath the car.

I never had this happen other than those two times which both had the combinations of idling for 10+ minutes in drive coupled with hotter than usual weather. Is this a thermostat issue? I tried to do some searching on here and also saw stuff about bad head gaskets messing up the coolant line pressure and whatnot. Would keeping the heat on full-blast in similar situations do anything to minimize the issue?

For what it's worth my dashboard temp gauge has never seemed to work since I've owned the car. The needle always stays at the bottom - EXCEPT on one or two occasions (Friday in the drive-thru being one of them) where the needle rose to about the mid-point and then dropped again once I got moving.

Honestly I think I'm about done with this car but would like to know how serious this issue is timetable-wise. I have nothing against Saabs but this particular one has given me nothing but trouble. I like to blame the previous owner but who knows.
 

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There are two engine coolant sensor probes. One feeds the ECU and helps it compensate for cold startup. The other feeds the ICE (Integrated Central Electronics) module, which uses the information to control the dashboard temperature gauge and to kick the radiator fan between off / on-low / on-high via its low and high relay. This sensor screws into the back side of the block (which is the driver side on left-hand-drive / North American SAABs).

While it's possible you have a failed coolant gauge in the dashboard or a failed ICE, it's more likely that the corresponding coolant sensor is not working as it should, either because it has failed or because there's a wiring fault. This can lead to overheating, usually when the vehicle is 'standing' (e.g.: idling and not moving) due to inadequate heat exchange in the radiator, because the ICE module doesn't know when to kick the radiator fan on. While the car is underway, the air flow from moving forward may be enough to keep the engine from overheating some of the time, at least when the ambient temperature isn't too hot, though it will be a lot less precise than is ideal, because the only temperature regulation at that point is coming from the engine thermostat opening and closing coolant flow to the radiator.

With the air conditioning off, does the radiator fan ever run? Does it run immediately after you shut the engine off after a drive? If no to both, it's more than likely the sensor or wiring for same, or an ICE internal problem, though the latter is less common I think. It's also possible there's a problem with the radiator fan wiring, low-side resistor, or one of its relays, though none of this would explain the usually-low coolant temperature gauge readings you're describing. If the sender, ICE, and gauge were all fine and you were seeing these readings, an explanation might have been that the engine thermometer valve was stuck open-- if this happens in the winter, the engine may run cool or cold, but this would not explain why your gauge was indicating low while you were overheating, and generally speaking, during the summer months, a stuck thermometer won't be enough to prevent the engine from getting warm enough to at least indicate something on the coolant temp gauge.

If the problem is the sensor, it's a $15 part that takes only a few minutes to swap, although you'll have to deal with spilling and topping off coolant if you don't drain the coolant first. If you haven't flushed the coolant or don't know when it was flushed last, or don't know what sort of coolant is in the engine, this might be a good opportunity to flush and replace with Zerex G-05 or a similarly appropriate coolant for this engine. (Generic green propylene glycol is not an appropriate coolant for this SAAB).
 

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I'd start with a new temp sending unit, thermostat, and complete flush. Maybe even a water pump. It sounds like its boiling over. A pressure test would be in order too. Also check or have someone make sure the radiator is flowing freely. Sound like a lot of work, but this will insure your coolant system is right.
 

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A friend told me the other day I should be using Dexicool in my 1995 V-6 2.5 liter cooling system??? He said this came about because of the GM connection!!! I had never heard this before...always the Zerex G-05...any insights on this...I want to treat my "baby" right. Love my Saab!:confused:
 

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Been using this for many many years in all my bikes and cars with never a problem. Use it and don't look back. Supertech 50/50 and regular.

 

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Discussion Starter · #6 ·
Hey guys I appreciate all the responses and insight.

In the interim until I get those things tracked down is it possible to just blast the heat when I'm stuck in idling situations to force the fan on?
 

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I have the same problem, had steam coming off the engine when i was stuck in traffic on a hot day, temp gauge has not worked for a while, called out a roadside repair as i was in the country side and had nowhere to get water to top up system, he topped up system and ran a few checks and it turned out it is the
sensor not working which is stopping the gauge from getting a reading and also not switching the fan on, he bypassed the sensor as a temporary measure which means the fan is running all the time even when engine is off so I have to pull the fuse to stop it until i can replace sensor.
 
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