Years and years back, had the tach drive cable back out of the case of a 985. Tach went crazy but the engine was running fine. Then noticed the oil pressure and temp were both going down. Too much weird stuff going on so feathered the engine. Turns out it dumped the oil so fast it wasn't going bsck into the tank and so the temperature reading went down. Only engine failure I've seen where the temp wasn't rising.