This is probably a complete newb question, but should the radiator fan on my 72 f250 390 be spinning constantly (from key start to shutdown)?

 

Depends.


Does your rig have an electric fan, a clutch fan, or a mechanical fan?

 

If it is just hard bolted on to the engine, then yes.

 

It's a mechanical clutch fan (hard bolted)

I asked because some "race mechanic" at an auto shop mentioned that my truck fan shouldn't always be running. his thoughts seemed stranged but wanted to confirm on this site.

Thanks for the replies

 

Dump your "race mechanic".

 

Probably yes. The fan on my 72 F250 was bolted to the engine. So, if the engine was turning, the fan was turning.

Unless you have a fan with a separate motor or a clutch, it would be bad if the fan were not turning all the time.

 

Thanks! Noted lol

 

Do yourself a favor. Fire up the rig, open the hood, stare at that set up for a while, and try to figure out any way whatsoever that it would not turn all the time.

And try to get that race mechanic over there to help you out.

And out of curiosity, how did this come up? How did it come to be that a "race mechanic" told you that your fan shouldn't be running all the time?

 

"race mechanic" is on crack... do not let him or her touch your rig.


Drive away.... FAST!

 

If it shouldn't be running all the time, while you have the "race mechanic" over to look at it, get him to show you how stop it...

 

The race mechanic was telling me how there is a clutch in there that releases with springs somewhere, and that I would probably want to looking into getting a new fan/fan innards, or change over to electric because it would free up something like 30HP....LOL! I literally laughed when he said that. He replied with; you think I'm kidding but I've been building cars for 40 years.... Etc etc...

 

Free up 30 horsepower?
I could belt that fan to a 2 hp Briggs Stratton lawn mower engine and rev the blades off it. That has been done.
Get rid of the guy.

 

I had a stock, fixed 4-blade fan on the 240 in my truck. If the engine was running, the fan was turning at the same speed as the water pump pulley.

I replaced it with a 7-blade Ford fan with a clutch. As long as the engine is cool, the fan turns at a slower rate than the water pump pulley but, it still turns. As heat from the radiator blows across the thermostatic spring in the middle of the clutch, it has more positive lockup to spin the fan closer to the speed of the water pump pulley.

 

And watch out for the direct drive type when you have the hood up and the motor's running. Your hand/fingers will only get in the way of the meat grinder. That's why they eventually put the warnings on the fan shroud (if you actually had one).

 

Good Info. Thx!