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Fix for frequent heat loss in cold. Posted by Kevin K [Email] ![]() ![]() |
Some noted loss of heat in cold weather, when in traffic and gage rises a little.
If cooling system is healthy, install the 'normal' saab 89C (192F) t-stat, and problem should stop. Although many (me) use an optional 82C (180F) t-stat, it can cause this problem ... esp the wahler version.
Did some cook-top testing, since I have the housing out. With proper t-sat, it opens at 193, and keeps gage around 1/2 up. In traffic, temp rises and fans come on at about 200F by oem fan switch. No problem. But if temp rises more (example fans not working right, or fouled rad) then t-stat opens more and closes off the heater loop at 15 deg (wahler) or 20 deg (waxstat brand) above opening point of 193F. These 'heater-loss' temps would be 208F and 213F, both above the normal control range.
If you use the cooler 180F t-stat, then heater shut off is at 195F-wahler or 200F-waxstat, and heat will be lost before fans cool coolant down in traffic situations. Situation is actaully worse than this, since in cold weather, actual fan kick-in temp can rise 5 degF, a bit higher on gage, vs summer operation.
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waxstat seems better than wahler in avoiding heater loss .... anyone know who supplies waxstat? is oem same as wahler?
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DON'T use VW-82C fan switch, with 82C t-stat, unless you are temporarily running with a bad, old, plugged radiator ( plugging will raise fan kick-in point 10 deg F or more. Use of VW switch on healthy system will needlessly wear out expensive fans, and not significantly help engine life.
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