[Z Code 400]

Steve,

If I take the fan off the car, it will run hot even at 70+mph...Robert

[old66tiger]

What's a good test to see if the clutch isn't working like it should? The belt squealing thing is really bothering me and I am pretty sure that I have exhausted all other avenues thus far.

[Joel Koontz]

old66tiger,

I did a Google search and got a bunch of responses with "clutch fan test". I looked at some of the results and most seemed to be about determining if the clutch was engaging properly VS disengaging properly(which seems more likely to be your issue)

If the engine is off/cold and you try to turn the fan, does it turn easily?

I think it should turn with just a slight resistance. The tests indicate that if it rotates more than 5 times when you spin it it should be replaced. That makes me think that it should probably spin fairly easy, just not freewheel.

If yours is reluctant to turn(or stops instantly) it is probably bad.

Just my opinion, I'm no expert on this.

How are you checking belt alignment?

Eyballing, and/or measuring out from the block/heads may work, but I have found that it is not nearly as reliable/accurate as using a straight edge. If you lay a straight edge across the face of a pulley it will show you if the adjcent pulley is in line.

[Joel Koontz]

Steve, I doubt that the mechanical fan is slowing the car at 70 MPH, it might at some speed, but I would expect it to be a lot higher than normal highway speeds. At that speed it may be that the air coming through the radiator is just "helping the fan turn" which probably reduces the HP draw. Probably quite a bit compared with same engine speed and car stopped.

Z-Code, if you need the fan at 70 to prevent overheating, I think it suggests the rest of your cooling system is not working properly. Without correcting those issues, an electric fan would probably not be a good choice for you.

[Z Code 400]

Originally Posted by Joel Koontz

Z-Code, if you need the fan at 70 to prevent overheating, I think it suggests the rest of your cooling system is not working properly. Without correcting those issues, an electric fan would probably not be a good choice for you.

It is based on the aerodynamics of the vehicle. I have seen many Corvettes that would not cool without a fan as there is nothing to create negative pressure behind the grille.

During qualifying at the 1969 Daytona 500, Ben Arnold tried to pick up some horsepower by removing the engine driven fan on his Ford Torino Talladega. He experienced heating problems at 170+mph.

Very common issue...Robert

[Formulafr]

Originally Posted by Joel Koontz

If yours is reluctant to turn(or stops instantly) it is probably bad.

well, so why my 30 years ols fan cluth (probably an heavy duty) was mostly free and the new i've put was just like you describe (hard to turn)?

[lust4speed]

The silicone fluid settles to the bottom of the clutch mechanism and will take a little while to distribute itself aafter startup, and the fan will be engaged for awhile. The settled out silicone will also produce a noticeable drag when testing it cold when turning it by hand. If the silicon has leaked out, then the fan will free-wheel cold and this is why they suggest testing it for free spin.

[Steve C.]

Do remember the engine heat generated at 70 mph with gearing for a lower cruise rpm will probably be less than a car at 70 mph with differant gearing and a higher rpm. I saw a differance out on the open highway with my overdrive transmission compared to the TH400 trans just by the approximate 600 rpm drop.

The speed and rpm involved in a Circle Track operation is another situation.

[1971WARBIRD]

Jay,have you been able to get any numbers with your combo?interested to see how it works out as i plan a clutch fan for my 72 Lemans.