[Derrick]

Had some fun and games yesterday with my '95 9000 CSE Turbo. The cooling fan does not seem to be working on the high speed setting. This meant that I had to drive 200+ miles with the heater on full (windows and roof open) to stop the rad. temp. going through the roof!
Anybody got any suggestions? I plan to have a good look this afternoon. I have read the previous posts about the cooling fan system - where are the resistors on my car? My friend's '94/'95 Aero has the resistor in a pretty obvious place (resplendent in its gold coloured heatsink) but there is nothing so obvious on my '95.
Thanks for the help - in anticipation!

 

[Harvey]

Derrick,
Are you sure you have a two speed fan?
If you have then the temp switch in the radiator will have three wires emerging from it ( two for the single speed ).
There will be two fan relays in the relay box and the resistor is always ( according to the info. that I have )fixed to the fan motor housing.
In my experience the fan ( single speed on my car ) only comes on when in traffic or driving slowly in very hot weather.
If you are in Britain I certainly wouldn't expect your fan to be operating on a long journey in November!!
You may have some other reason for overheating.......

 

[Derrick]

Thanks for the reply. The whole things seems odd. In the fuse box there is a relay in the 'High Speed' fan socket along with a 30 amp fuse. With the fan running I can pull either / both of these with no effect on the fan. There is no resistor present on the fan housing (I thought I only had a single speed fan because of teh lack of resistor) There is no temp. sensor in the rad. The fan usually comes on after a short run and switches off after 30 secs - 1 min. But now it stays on fro a couple of minutes and does seem to have the ferocity it previously had (you used to be able to feel the draft quite strongly when stood next to the car) I agree that there might be something else to look for as it got very hot within 20 miles of starting the trip. The outside temp. read as 10 - 14 degrees C. Any other suggestions?

 

[Harvey]

Derrick,
Given that your basic symptom is overheating ( seemingly )I would be inclined to ignore the 'fan problem'initially and find out what is causing the apparent overheating. As said before it is not likely that the fan should have been needed on your long journey in the cold.
The most likely cause of the overheating is ( assuming you have water in the system

)a defective thermostat.
It could also be:- failing water pump, defective head gasket.
Just possible you have a defective temp. gauge / sender unit.......

The 'Townsend' website has useful info and wiring diagrams for cooling system. www.townsendimports.com The diagrams do not match my car exactly but were very useful for tracing a non working fan problem on my '92 9000.
Btw. the temp. switch is on the left side( looking from front of car )of the radiator about two thirds way down, just in case you missed it.
If you don't have this, or the resistor, it seems very strange......
You may get some other ideas from some others when they have finished playing with their fireworks. Please keep us posted on what you find; this is interesting.
Sorry I can't help more.....

 

[Derrick]

The plot thickens!!! HAving calmed down (and cooled down) Yep - your right I should concentrate on trying to work out why there is an apparent overheating. I considered the head gasket, but there seem to be no other symptons - no oil in the water (or water in the oil) and no loss of water or oil. Assuming that the fan system is working, surely speed 2 would kick in if the thermostat ahd stuck closed. Failing water pump might be a possibility - but the temp gauge plummeted (sp?) once the heater was turned on. I am begining to suspect the temp sender unit - but will have to wait until weekend to find out for sure (work, dark nights, life). As ones mind becomes quite focussed when a gusge reaches for the red, I shall continue to melt my feet with the heater until then!
Now the thick plot bit - the 2 speed fan. I have both relays, the 30 amp fuse and experience (in summer) of the fan being quite vicious, but I have no signs of the resistor (unless it is well hidden). Also, there is no signs of the thermostatic switch in the rad. There is a blanking plate where one would expect to find it! Where is my switch? Where is my resistor? I know the history of the car - until me it had always been serviced / repaired at dealer (company car from new) so it's not been hacked about. Any more ideas? Thanks guys

 

[Derek]

 Assuming that the fan system is working, surely speed 2 would kick in if the thermostat ahd stuck closed.[/b]

This is not necessarily true. If the thermostat sticks closed then the coolant does not circulate through the radiator so the radiator doesn't get hot. The temperature switch for the fan is (usually) on the radiator so that doesn't get hot either so the fan remains off.
The sender for the guage is in the block so it will indicate that the block is overheating. The heater matrix is not shut off so any heat output from there will help to cool the engine.
All of which inclines me to think that in Derrick's case the thermostat has stuck closed. Goodness knows where the switch for the fan is though? Maybe I should have a look at my '96 model.

 

[billj]

You can check that theory, sort of. Does the radiator (or the top hose) get hot? If not, the thermostat is stuck completely closed. If it's stuck partially closed, then things get more difficult, as hot water will be flowing into the radiator and both that and the top hose will get warm/hot, but there may not be enough flow to cool the engine effectively. I would have thought that in this case, though, the fan switch would eventually trip.

 

[Derek]

Yes I suppose a partly closed thermostat mucks that theory up.

I just checked my car at lunchtime and it doesn't have the fan thermoswitch where I expected it either. The radiator has a blank at the offside just ahead of the turbo, Hmm!
I'll maybe have a look at the weekend and see where they have put it.

 

[gordoncooper]

To add a another thought to your problem. Earlier this year I had similar problems with overheating and the fan not switching on (I only have the one speed fan). When I looked to replace the thermostat switch I found that one of the connections in the connector block was extremly corroded and so stopped the fan switching on. Maybe you have a similar problem so that the slow speed works but there is a bad connection with the fast speed.

Gordon

 

[haydon]

I had a similar corrosion problem with my last Carlsson. In my case it was the loom side of the fan switch connector that was the problem, the wire had completely corroded away and broke off. Lucky for me it was when I was doing preventative maintenance rather than driving along...
David

 

[billj]

I think we need not get sidetracked about the fan at the moment.
On a long run, the fan shouldn't even be necessary, yet the car still overheated. Even if there is something odd about the fan, that isn't what caused the car to overheat in this instance. Also, the fan stays on for a long time after a run. Perhaps it is not having much effect because the hot coolant isn't reaching the radiator, so the engine takes longer to cool to the point where the fan switches off? It does not have the ferocity it should do - perhaps because the air it pulls through the radiator doesn't get hot?

Since we can't find the fan switch (does a Trionic car have one at all? I seem to remember reading that the Trionic ECU controls the fan), we can't make any assumptions about what the fan should be doing given a particular fault.

All this is assuming that your run wasn't 200+ miles of sitting in traffic, Derrick. If this assumption is correct, I favour the thermostat, as it seems to be a common cause of overheating on the 9000.

 

[Derrick]

Thanks guys. I had not heard about the fan being controlled by the ECU before (sounds very scary). Both the top and bottom hoses of the rad. do get warm / hot and so a sticky thermostat is another good lead - think I will get a new one and stick it in (although I don't know how much they are yet! but given the time and effort required to access the current one this seems like a worthwhile venture - price permitting. So the likely next step (this weekend) is to test the sender in the block and find out if the car really is overheating and possibly / probably change the thermostat mmmmmmm! Please keep the suggestiions coming - I'll feedback whatever the outcome. Thanks.
PS the trip was on A roads at approx. 50mph all the way (very approx.)

 

[billj]

Originally posted by Derrick:
[qb]although I don't know how much they are yet![/qb][/b]

Last one I bought from the dealer (I keep all my receipts) was £8.73 + VAT (comes complete with the rubber sealing ring). I think it's cheaper from Euro Car Parts, but I think the sealing ring is separate, which brings it near the dealer price and postage makes it ridiculous unless you are buying other stuff at the same time. Also the unit from ECP is an 82 deg. unit, which I think was optional in this country. The dealer supplies 89 deg. as standard.

I wouldn't be tempted to go for the lower one just because you have an overheating problem. The 89 deg. one should work fine and the engine will run more happily at that temperature. If the thermostat isn't the problem, then putting an 82 deg. one in there won't make it any better.

I keep meaning to write up the thermostat replacement procedure for my web site, as I have all the notes and photos.

Oh, and make sure you get decent antifreeze. The Saab stuff is a bit pricey. I use Mercedes-branded stuff, which is also a bit pricey but is said to be very good. I think it's still cheaper than the Saab stuff. Mercedes stuff costs about £21 for 4.5l.

P.S. If the thought of the ECU controlling the fan is scary, what about all that fuel and sparks, never mind the boost pressure?

 

[Harvey]

There is a replacement procedure for the thermostat on the Quasimotors site at :--
http://www.quasimotors.com/stat1.htm

 

[haydon]

also see my post in the 'townsend diagrams thread'.
In '95- car the fan is EDU controled (via the relay) by a modified (2 wire) sender in the block, not by a fan switch in the rad.
Because the sender is in the block, the fan should come on even if the thermostat sticks shut (another theory out the window).
Unfortunatley I don't have the specs or wiring diagrams for this setup so I cannot suggest what to test.
Can you clarify the symptoms, I'm struggling to follow.
1) Does the fan come on (at all) when the gauge gets to 9 o'clock (or worse)?
2) at this point, or before, does the top hose to the rad get hot?
If yes to both I'd say rad or pump is faulty.
If no to 1 (and yes to 2) then I'd say the sender/EDU/relay is at fault.
David

 

[Derrick]

Thanks David, and Harvey. The fan is switching on low speed as the neddle is rising (around the 9 o'clock stage), don't know if the hose is hot at this point, but will find out on Saturday. Have got a new thermostat (£9.17 + vat from main dealer) to try that. But now I will add the pump to my list of things to check when I'm maximising daylight! (How can I check the pupm without dismantling the other half of the car?).
Now an aside that will cause alarm bells to ring everywhere - about 1500 miles ago I changed the heater matrix and so had disconnected a lot of the cables between the engine bay and the false bulkhead, could this fact be related (I hope not)? Another thing to check. Thanks... for now... Derrick

 

[EdCambridgeGuy]

Simple question from a (saab) simple person... If the theromstat in the radiator wasnt working correctly would it register a value on the water temp gauge on the dashboard??

 

[StephenA]

Ed

The Temperature sensor for the gauge is in the thermostat housing on the engine block. The one on the radiator only controls the radiator fan as far as I am aware.

Steve

 

[haydon]

Ed is correct, except in the later models ('95-)there is no sensor in the radiator. The block sensor is a two wire version, sending to the temp gauge and the EDU (which controls the fan).
David

 

[Derrick]

Just an update. Didn't get chance to do too much last weekend - but have done some more investigating. I have decided that I am going to change the pump as well as the thermostat! This is largely due to the comments from DrD - and the slightly discoloured patch along the bottom of the pump I found once I had removed the sheild underneath the engine bay - oh and the note on the townsend / quasimotors site that notes water pumps going after approx. 100,000 miles (I'm closer to 150,000).
Will let you know what happens!
Derrick