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1995 993 oil cooler fan modification


Vehicle Information: Model: 993; Year: 1995; Body Type: Coupe; Total Mileage: 50,000;

Perhaps you can weigh in on a question regarding 993 oil temps. You've commented in the past about the 993 being prone to valve guide wear, and it stands to reason that heat contributes to it, which is why many people remove the undertrays on these cars. A weak spot on the 993 is ceramic resistors that control the fan speeds on the oil cooler and AC condensor. They are located in a spot where temperatures are hot, and they eventually fail and cause the fans not to operate when they should. On the oil cooler (passenger) side, removing the headlight from the bucket reveals a connector, which, when disconnected, forces the oil cooler fan to operate continuously at the higher of the fan's two speeds. Caught in crawling summer traffic the other night with the fan in "normal" operation, I observed my oil temperatures rising to midway on the gauge, the 9 o'clock position, between the 194 degree and 248 degree marks. It stayed there, but even after breaking free and driving 60 mph for 20 minutes, it went no lower (it was quite a humid night).I pulled the headlight and disconnected the connector. The fan now runs at high speed continuously. Two days later, I got caught in Boston rush hour traffic, temperatures around 90 degrees, sunny, high humidty, idling and crawling forward with the AC on. The oil temperature never broke the 194 mark on the gauge, remaining about a needle's width below, even after 30 minutes of little or no movement.The question is ... what is the optimal oil temperature on a 993 engine? Can the oil be too cool or the oil cooler too efficient for street driving? Obviously, Porsche put the cooler there with a thermostat that opens around 180 degrees, so it would seem that the "worst" that could happen would be the cooler thermostat opening and closing more frequently due to the increase efficiency of the cooler with the fan operating. Do lower oil temperatures help valve guide wear? Any drawbacks, aside from the theoretical wear on the electric fan on the cooler?Some people modify the car with a switch to allow the fan to be turned on at high speed from within the cabinet for use at the track, etc. Thanks

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