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Discussion Starter · #1 ·
Hello fellow Saabers-
I haven't been here with a Saab problem in a while (she's been very good!) but now I'm in need of some help.
My car recently began to run hot...now, up until now, even in Atlanta summer heat, the needle NEVER got above the 1/2 way mark. The fans always kicked in as normal and kept it nice and cool. Well suddenly the needle rose up to the red mark, like the thermostat had stuck or something. I was at a traffic light, and I assumed that when I resumed driving, the airflow thru the radiator would cool it down a bit. Nope! It STAYED hot, in the red, the whole entore way to work. When I'd stop at the next light, I could here the fans cycling on and off like they usually do, yet the needle on the dash was pegged at high noon! I pulled over to see what the hell, and everything *appeared* normal...full coolant level, no leaks, and fans cycling on and off. I opened the bleed valve thinking I might have some air, nothing but water came out.
What bothers me is that when driving, the temp DOES NOT go down at all. The water pump is new, there's no leaks, and the thermostat is new. It's as if the water was not circulating in the engine whatsoever.
The only thing I can think of is that there's a big air pocket in there that aint coming out, a blockage of some type, or the guage or temp sensor has gone bad. Anything else I can do or check? I plan on spending a little time with it this evening when I get home.
Please note, I thought maybe the thermostat was stuck so I pulled it....no change! It still ran max hot, no matter what speed or sitting still!
Any and all help is appreciated my friends!
many thanks:D
PS: 1986 8V C900 N/A
 

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Sounds like you need to check the radiator for blockage. Move your hand over it when it is hot to check for cool spots. I had to replace my radiator due to this a few years back. Since it overheated you need to replace the thermostat as well.
 

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Wacky temperature gauge would be the first thing I'd check. There are earthing points on the rear of the instrument cluster. When these fail it can cause some of the instrumentation to misbehave.

My 8v's temperature gauge will suddenly ping straight upto max, even though I know the car's not overheating.

I think if the radiator was failing then the rise in engine temperature would be more gradual, rather than a sudden change during one journey. If the radiator core collapsed then yes that would cause a sudden change in engine temperature, but you'd also have had coolant pouring everywhere and probably a blown headgasket. Having said that, radiators are among the most neglected of devices - when was the rad in your car last replaced?

Also check the engine oil dipstick for mayo and the expansion tank for oil deposits. A blown headgasket would definitely cause sudden overheat. However, I still think the gauge is fibbing to you ;)

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Discussion Starter · #5 ·
Thanks everyone-
I've checked the oil a couple of times today, no sign of anything other than nice, clean oil! And there are no leaks or anything like that either. I've bled it 2-3 times today with absolutely a straight stream of coolant coming out of the valve. No air! It's quite frustrating actually HAH
I'm at work right now, so the car's outside cooling down. I'll go out at lunch and get it up to temp, and check for cold or cool spots on the radiator I guess. When I get home I'll flush it out and refill it, and see of that makes a difference of any kind.
What makes me think it's the guage is that the fans cycle on and off, just like normal, as-if nothing's going on.
And this while the temp guage shows it pegged in red! I mean, wouldn't the thermo-fan switch keep the fans on constantly if it *were* actually as hot as the guage says?
BTW everything in the cooling system is fairly new, replaced it all last year when I did the A/C retrofit.
Thanks again guys, I appreciate it!
 

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The temp gauge in my '88 900S (junked back in April due to rust :cry: ) had suddenly started to read full-hot a year earlier. And, as with yours, all cooling system components were new; the fans cycled as normal, and nothing suggesting actual overheating happened:confused:

I figured the gauge had gone bad. If your needle jumps to full-hot as soon as it begins to move off the cold position, the gauge is defective:(

*edit* As the fans cycle, the temp. sensor's resistance varies between about 45 and 55 ohms. (This is the small sensor in the head that drives the temp. gauge, not the fan switch in the rad). Pull its wire and measure the resistance when your engine is fully warmed up--see if it's as above. If so, the gauge is definitely bad.
 

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Discussion Starter · #7 ·
PROBLEM SOLVED!
I was driving home and it was pegged straight up like it had been doing for days..it suddenly kind of jerked up and down a little, and went to the red again.
I smacked the instrument cluster face, and BAM it went right back to normal, and has been acting perfectly ever since! :D It gets near 1/2 way, and the fans come on. It goes down. Back to normal!

Call it the 'Fonz' fix.

Anyway I'm glad it's not actually overheating, what a big relief! I celebrated by giving it 1/2 a tank of high octane.

Thanks all for the help, cheers:cheesy:
 

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:lol:

Having had my car at the red mark, and overheated several other cars, I can tell you that it is always very obvious when the car is overheating that much just from the heat coming out the engine bay.
 

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I was going to suggest that the car might behave after a good beating, but didn't want to be a jerk and post a non-helpful reply. Looks like I was wrong! This does the trick for the temp gague on my 88 900S, but not for the gas. Go figure.
 

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Overheating

Thought I'd share my experience of overheating. Mine started going into the red quite suddenly, I changed the thermostat and antifreeze but it had no effect. It wasn't till I took out the radiator that I got to the cause, all the little fins had come off it seems in one go!! :eek:
Basically, the coolant was as hot coming out of the radiator as it was going in. It also explained why it tended to overheat more at speed than in stationary traffic, were the fans could cope with the engine heat generated at tickover.
 

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Back to bread and butter gents, an electrical temperature gauge can fail and have bad contacts and so on and on, a simpler and more basic gauge is better IMHO, a simple temperature probe is very accurate and dare a say, no i will say its better than an electrical gauge and the 900 gauge is pretty rubbish, what is the green in degrees? who knows, get an after market gauge for only $10 and be safe and secure in the fact your engine is not boiling like a hot totty:cheesy:
 

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Hu Flung Dung said:
PROBLEM SOLVED!

I smacked the instrument cluster face, and BAM it went right back to normal, and has been acting perfectly ever since! :D

Call it the 'Fonz' fix.
Chalk one up for the Flungster. Percussive Maintenance can be quite effective...
 
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