on my 300SD. As soon as I turn the key to fire up the glow plugs, the fan is kicking hard. This is not normal, correct? Normally it only kicks on when the engine gets to a certain temperature?

The vehicle runs/drives great and never gets over 80C. Please advise.

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1985 300SD - 167k miles
1992 F350 7.3 (Soon to be converted to 2 tank Veggy/WMO)