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97 Aero slightly over heats after extreme speeding.

3122 Views 15 Replies 5 Participants Last post by  inspectorman
Okay so I really love taking care of my poor old saab and I am really panicking if anything seems to be going slightly wrong with it. So my question is today I was driving on the highway home from my mall and this 2000ish ford mustang pulls up beside and challenges for a race, I ignore because I pay no attention to idiot spoiled kids and there under powered 6cylinder wannabe muscle cars. Well he then swerves and front of me and that pisses me off so then its on, well I beat him to my exit(4th gear 120, he was 3 car lengths behind) well as im slowing down to the red light off my exit I notice that my aftermarket temp gauge(which reads very accurate) starts to rise and hits about 230ish so I quickly pull into a parking lot and let her sit for a while. i popped the hood expecting to see a leak or something but all looked fine. Later I left and on my 35 minute drive the rest of the way the temp stayed pretty normal. What Im wondering is like because of the high speeds would that have effected the engine that much to make it over heat for a little? I'm really confused and would like to find some kind of answer.
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Doesn't sound unreasonable. There is much, much more heat produced when you're travelling at that sort of speed. With the age of your car (you don't say what year/model but it's going to be at least 12 years old...), it's quite likely that the radiator isn't doing as good a job as it might be, probably as a result of mild furring inside and bent fins from stone impacts over the years. Plus your engine may have lost some of it's efficiency. Put all this together and it could be struggling to dissipated the extra heat.
As its a 97 then the stock gauge will only read "nominal" readings, if it didn't go high at the same time as your aftermarket gauge then it seems normal, perhaps built into the ECU as a stable parameter?
Yeah idk I was just kinda worrying about it, I had recently replaced the whole entire heating system(radiator,hoses,heater core, overflow tank, thermostat,temp sensor, coolant level sensor) that took a lot of time and money even thought me and my dad did it. And its weird also maybe someone could answer this too. The factory temp gauge doesn't really work, like it will go up a little bit on someday s and others won't work at all and like when the days it works a little bit that's it, It only goes a little bit above the blue bar. Now the fan still works though, it will kick on when the car starts to hit about 180ish I believe(that's Fahrenheit). Yeah its got like 200,000 miles on it now too so idk. I have done a lot of work to it as like replacing and taking care of it and I just don't like breaking down when I'm far away from home. Oh and to Mark E. my car is a 97 9000 Aero, sorry for the confusion.
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Aha! Sorry, I missed the model info in the thread title- must read it all.

From what you've said about the temp gauge behaviour I would suspect that the thermostat is faulty, possibly stuck part way open. This would also mean that you wouldn't get full flow as it heats up.

The temp gauge on that MY isn't a real one as such- it shows cold until the engine gets up to the correct temp, then stays at around 8 o clock almost without moving until it starts getting very warm. You might also have a faulty temp sensor. It would be worth getting hold of an OBDII reader with live data to see what is really happening.

When you start the car, does the top radiator hose heat up slowly or stay cold then all of a sudden get warm? If the former, you've got a faulty stat.

If you look at the picture Mark E has as his Avatar then that shows the normal position for the temperature guage. This is a 'virtual' gauge which outputs what the ecu thinks you should know. I suspect that you are a victim of why Saab decided to change to this system back around 1994. Prior to that the gauge was 'standard' outputting what it got from the sensor. Too many owners were taking their 9000s back to the dealers worrying about overheating. The virtual gauge shows 'cold' until normal running temperature and stays there until it gets really hot and you ought to know about it. The needle then jumps up to the 'hot' area so that you notice.

The fan is driven by a separate sensor mounted in the radiator. The gauge is driven by the one on the stat housing. A third one mounted under the middle of the inlet manifold in the head and feeds the ecu for mixture control. - simples !

Your self fit 'standard' gauge gives the 'real' temperature at all times. You may still have a thermostat problem though I wouldn't have thought that it would fail statically and inhibit flow at high temps as well as not closing. I had a 'failed open' stat in Mrs P @ K's LPT and this gave very erratic readings in cold weather. It would sit resolutely in the 'cold' blue section them jump up to 'normal' for a few seconds before dropping back to 'cold' again. It would cycle up and down fairly regularly. A new 89 degree stat sorted it.

200k miles - just run in !

Paul @ Kippen.
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Yeah I kinda understand what you guys are saying, I don't think I had replaced on of those sensors you where talking about Paul so I'm going to look into it a little more. See what I don't understand is like you guys are talking about replaceing the thermostat with a factory one but I know you guys know a lot more about Saabs then a silly American boy like me but I just replaced the thermostat with a factory one when I did the rest of the heating/cooling system and I mean like this was only about two months ago. But yeah I have to change my oil here soon in like 200 hundred miles and that will be prolly in the next week. I drive a lot(like 40 miles to school and back then 50 miles to work and back so that's 90 miles a day). So I will prolly have my dad or someone take a look at it with me then. Also is there a way of telling if your water pump is on its way out. I haven't really thought of that till now but I was just wondering if anyone knew if there was a sound or something to look out for.
Like I said I really am grateful of all the help this website has been.
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Oh and also like I said before too. My stock temp gauge doesn't work for anything. Like a while ago I had a over heat in winter cause of a hole in the one heater hose. I had stopped very quickly in good time before any damage was done. But after that my temp gauge has never worked since. Don't know why but it just doesn't work at all. Barely any movement from it. Just goes up to about the blue cold line and stays like that. And I drive pretty long everyday so it's not like its just super slow or anything.
Looks like one of your temperature sensors has given up - or the thermostat is misbehaving. I'm not sure if it's possible to fit it wrongly but someone willl be along soon to tell you.

Water pumps tend to work for ever - then start weeping from the shaft as the bearings / seals give up. Quite easy to spot as the coolant streaks and evaporates.

Don't forget the obvious - are the sensors still connected after you did all that other work on the heater hoses, thermostat replacement and so on?
Did you replace the thermostat with a 82 or 89 degree one? There is different temperatures in which they open y'see. Here in the UK its best to use the 89 degree Celsius one as it opens later with a higher temperature so it doesn't allow the engine to run too cool, as mine did. Bought the car and it rarely got a little above the blue, took it off and found it was a 82 degree (had it stamped on it). Changed it for a 89 degree with the hole on at the top and its been fine ever since.
Still have issues with a dodgy connection with the sender next the thermostat but thats by the by :)
Yes I had replaced it with a 89 degree(192ish in Fahrenheit) one. So like and yes as far as I can tell everything seems to be fine. But the one thing I noticed is I do not see a sensor directly on the radiator. When I had replaced that I don't believe there was one on there unless I did put it back in and just don't remember it. Could someone please post a picture of it and its location on here for me? Thanks
The sensor in the radiator was for the fan controller and I'm sure had been deleted by 1997. All radiator mounted sensors have the possible fault that as the coolant disappears due to a leak, the signal they send tends then to read normal or cold! ( Fan control was then taken over by the ECU reading the engine temperature). There should be one sensor in the inlet manifold, well hidden at the back and underneath; and one in the right hand side of the cylinder head as you look into the engine compartment.
Okay thanks for the clarification on that radiator one. ( Spend a 1/2 after work yesterday with a Rockstar Energy and a flashlight trying to find one on my radiator) Also I'm prolly gonna have my car up on a lift within the next week I believe so could you please give me the sensor's name/number? I usually use a parts website called because its in America and its good priced and always has the parts I need.
Temperature sensor 91 77 213 at back of engine

91 82 270 (1/8 thread) OR 91 82 205 (m12 thread) for the one next to the thermostat / IAC - so you'll need to check the thread on that one.

Charge air temperature sensor 91 74 442 on the big air feed tube running up from the intercooler to the throttle body.
Okay cool thanks for the numbers I'll prolly buy them here soon. Also The air temp sensor did you mean "charge" or "change"? Anyways thanks again for the help
Charge - think turbocharger - the air is "charged" - but with a part number there should be no confusion. That one should be easy to spot on your car.
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