Date: Tue, 09 May 2000 21:24:45 -0600 From: Bob Landry <utahbobnopsamnet> Subject: Re: 85 900T possible overheating?????
On Mon, 01 May 2000 09:45:29 GMT, grothnopsamiot.net.au (Gareth) wrote: > >>The other replies to your post had some good ideas, let me give you a >>couple more. >>Switch to the 82 degree C thermostat and fan switch. That will get >>your fans to come on sooner and reduce the heating problem. >>Check to see that your current fans are both working the way they >>should. Short across the terminals of the fan switch (upper left >>corner of the radiator) and see if both fans come on. Now you know >>that the fans are working. With the engine running, turn on the A/C; >>both fans should come on. This is as it should be. Consider doing the >>rewiring that will have both fans come on when the engine heats up, >>even if the A/C is off. (Check the site http://www.townsendimports.com >>for a wiring diagram. Keep trying, their server and ISP is acting up.) > > > >Here's a paragraph taken from http://www.townsendimports.com : > >==== > >For all 900s and Early 9000s with the two wire fan sensor, we strongly >suggest you swap the original fan sensor that turns the >fans on the first time at 92 degrees Celsius for one that turns them >on at 82 degrees. When used with a factory 82 degree >thermostat(8817538), this avoids the temperature overshoot problem >seen when getting in traffic after highway driving, and >maintains the gauge reading at about halfway. The sensor simply screws >into and out of the radiator and the wires plug right up. >We use a sensor made by Wahler for VW. You can get this sensor from a >VW dealer under the part number 823959481D, or >from us if you can't find it. That is a pretty old VW part number now, >but it is what we order it under. We have not found a >cooler direct replacement for later 9000s with the two stage fan, but >are searching. You can rewire them to accept the cooler >old style switch, but that is detailed in another page on this site. > >==== > >It firstly mentions replacing the two wire fan sensor with one that >turns the fans on a 82 degrees C. > >It then says: > >" When used with a factory 82 degree thermostat(8817538), this >avoids..." > You are correct, both items need to be replaced. >Now, my understating is that "when used with" means in normal english >"when the fan sensor is used with the factory 82 degree thermostat..." > >This would mean two items would need to be replaced - a fan sensor and >a thermostat. The thermostat regulates engine operating temp and coolant access to the heater core. The fan sensor monitors temperature in the radiator and activates the fans. >However, I thought the thermostat *was* the fan sensor.... ? > snip > >Oh, and to the original poster - have you actually done this upgrade? >Australian summertime can be quite nasty to a SAAB, and so I'd love to >know how much an improvement the 92 -> 82 degree C modification would >make in reality. > >Many thanks, >Gareth >Computer Systems Engineering, >University of Adelaide Yes, I've done it on both our Saabs ('85 900T, 260K miles, and a '92 900S, 70K miles) and there is a definite improvement even with the original radiator. Here in Utah, summer temps are routinely in the high 90's, so engine temp control is a definite priority. With an older car, an '85 for example, probably the best thing to do is to replace the radiator unless you're the original owner and have been compulsive in coolant flushes and changes. Eventually, corrosion takes its toll on heat transfer, and having the A/C condenser in front of the radiator doesn't help on hot summer days. Bob Landry
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