Hello all,

If the viscous fan on a 7,3IDI is good, how should he feel?

Mine has reasonable resistance when cold, though there is this one spot where the resistance is less when I turn the fan by hand when the engine is cold ( about 15 centigrade).

I just don't know the whatabouts with viscous fans, hoping somebody helps me out here?

Thanks.

 

The viscous feel is unimportant. What matters is whether the clutch is locking up when it is supposed to. That is a huge fan, and when it engages it sounds like a tornado under the hood. If you are not hearing a fan sound and your engine is running really hot that is your cue to replace the clutch.

 

That's basically it. You won't know if the fan is good or not unless you get the engine /hot/ - you basically have to run the truck towing a heavy load up a long grade and once the temps get up to like 220F it'll engage(and you'll really feel it at high RPM).

Problem is, if the rest of your cooling system is working right, you'll have a very hard time making that happen(as it should). As long as the fan isn't fully locked(with the engine warm and shut off, it should spin pretty freely), it's probably OK, unless you get to a situation where you can prove it isn't.
Also make sure to look it over for fluid leaks; that's pretty much *why* it would fail over time.

 

my fan clutch has never once locked up in the 28 years and 494,000 miles i have had my truck because i keep the cooling system in top notch shape.
my 02 on the other hand needs a radiator because 1/4 of the tubes are clogged, and the clutch regularly engages the fan.

 

you should hear the fan roar the first time you hit the throttle when you leave the drive way, as idling will usually not unlock it from sitting over night. if you rev it good it should slow down and pin wheel slowly when cool.