Recently my '06 6.0 was diagnosed by Ford and a P0528 code was one of the codes found. The tech noted, too, that the wire support for the fan clutch was broken, but the wires looked OK.

The problem seems to be intermittent. I've seen NO high temps on the factory gauge and the fan sounds normal (roars when it should and then goes quiet). My first run with my new Scangauge II showed a sudden jump from about 190F to 205F and then a drop to 188F and back to 190F.

At 300,000+ miles, I'm thinking a new fan clutch and thermostat would be a good idea. And, of course, a check/repair of the connection and wire support.

Anyone without a snowplow have a "snow plow" fan clutch installed? I'd consider one, but I don't tow commercially any more and don't think it's needed.