[CptMike]

Hi again, cg084...

Was that temperature at 70 a reading from your gauge on the dash though? I would assume that it was since you were traveling. That is why I was talking about an air pocket at the temp sensor - if there is an air pocket at the temp sensor the gauge will read lower than the actual coolant temperature, as the liquid would transmit the heat better than would air. Again, I can not address the 4.2L, but every car that I have owned with an electric fan had a temp sensor for the gauge, and a sensor/relay for the cooling fan (including the aforementioned Mercedes, a SAAB 900 Turbo, and several others.) If the sensor/relay for the cooling fan is actually touching coolant, while the sensor for the gauge is not, this would give you the activated fan while the gauge is reading low. An air pocket (read also as a low level of coolant in the block) would also cause the sensor/relay for the fan to activate sooner as there is less coolant to which the heat from the block can be transferred.

Please know that I'm not trying to play "the guru of cooling systems" here... I'm a long way from that. It is just that the symptoms so closely match my previous experiences that, where I a betting man, I'd put money on it. My concern is not about being right, but in helping you get your problem solved. Hope you don't take my post the wrong way...

Anyway - If I am wrong, I want to know about it, too. That way I will have learned something!

Hope it works out...