Fan running?

[Chakir]

I decided to go fishing for turbo leaks today, and found this was not going to be as easy as I thought with the fan running. It's 70 degrees out, just started the truck and let it run for a few minutes. My impression was it wasn't supposed to be running most of the time. Is that normal for it to run at startup and/or when parked, or is it misbehaving?

[jesilvas]

Ford has a TSB out for the viscous fan cluth. The call it "morning sluggishness" or something to that effect. Seriously.
The fluid in the clutch is supposed to get thicker the hotter it gets and finally engage the two clutches together at a certain temp.
Well if it's cold or really humid also, it will tend to stick until you get a little heat into it. Not that big a deal.

And the fan will always spin. But it will spin at a 1:1 with the fan pulley when it is engaged.

[ttyR2]

Ford Taurus electric fans move a ton of air. Might look into a pair of those.

[jesilvas]

No reason to turn to electric fans. The stock cooling system on the 7.3 is wonderful.

Also to the OP: how do you intend to look for turbo leaks? The best way is to get an adapter the will clamp around the intake on the compressor housing, pressurize from 15-20PSI and see if the pressure drops or not.

[Chakir]

My thought, and don't laugh too hard, was to fire up the truck, and take a piece of string on a length of wire and poke around to see if the string started blowing in the breeze. Obviously my plan was thwarted by the fan running. Not sure why I'm so timid around cars and trucks considering I'll take about anything else apart and fix it.

[jesilvas]

Well actually that sounds like a good idea.
Yes the fan is going to run while the motor is running. It will run more once the clutch engages at a certain temp.
Also if the motor isn't under load, you're not really building boost, so you'll have more vacuum than pressure on the intercooler system. But in that case it would try to suck in the string.
I can't remember who it was but they sold an adapter to test for leaks.

[Chakir]

Thanks for the reply. Glad to know I wasn't too far off in my thinking. I'm reading up on the boost leak detector now, and that sounds simple enough to build.