View Full Version : 03 4.6L DII Cooling System Operating Parameters

12-10-2007, 11:26 PM
I have posted this on the Discoweb forum so bear with me if you have seen it before:

RAVE and Workshop Manual state the electric fan comes on (A/C off) at 212 F and off at 204 F. Mine operates when the engine is warm while driving around town (today it was a foggy 55 F) and idling at red lights.

The vehicle has 40K on it and has done this under my ownership since being purchased with 32K miles. The dash gauge has NEVER gone over the middle hash mark; not in Denver in the winter or the beach and south Texas in summer.

The electric fan has never operated with the engine off to reduce heat soak. The coolant was flushed with O.A.T. coolant last year. The radiator fins are clean of debris.

With the engine hot and the electric fan running, the upper radiator hose measures 192 F and the lower hose 88 F. Live data stream on my scantool indicates 212 F when the fan kicks on and then it never goes above 212 F.

There has been no appreciable loss of coolant in 8K miles. I installed a new OE fan clutch just to eliminate it as a problem.

So, are the larger tranny and engine responsible for the increased operating of the electric fan? Do any 4.6L DII owners have similar experience with their vehicles?

I'm curious to know if this is normal for this vehicle or if it indicates a possible problem. I can't find anything in the archives about this. Any experience/help would be appreciated.