On the 79's, don't the mechanical fans (mounted on the water pump) turn in the same direction as the engine?
How does this happen?!
Thread Starter
Racer
Joined: Feb 2005
Posts: 373
Likes: 1
From: Bayonne NJ
How does this happen?!
Ok so im finished with the rebuild on my 79 and all the bugs are out.. so i thought.. When driving on the highway i noticed that my temps were rising.. checked all possible problems.. air in the system, fans not operating ect.. I hooked up my auxilary electrical fan to the ignition and had my mechanical fan also running.. after many headaches and questions asked on the forum i stop by my local mechanic to see if he wants to take a shot at it.. As we are sitting around BSin i decide to turn the car over but not start it.. just to see the direction the mechanical fan is turnin.. Turns out that the mechanical fan is pulling air from the engine while the electrical is pushing.. While at cruising speeds all the air is trapped between the two fans!!! Countless hours of tinkering and it turns out to be something like this.. My question is, is why would my mechanical fan pull the air away from the motor.. any thoughts on where to get the right fan?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by BanGnGearS
Turns out that the mechanical fan is pulling air from the engine while the electrical is pushing.. While at cruising speeds all the air is trapped between the two fans!!! Countless hours of tinkering and it turns out to be something like this.. My question is, is why would my mechanical fan pull the air away from the motor.. any thoughts on where to get the right fan?
Is anything on the motor aftermarket? The fan? Water pump? Anything like that?
Racer
Joined: Aug 2004
Posts: 419
Likes: 4
From: Lewisville TX
The Mechanical Fan should be pulling air towards the engine. The only thing I can think of is that somehow he has a reverse direction waterpump. Looking towards the car's nose, the engine should be turning the belts in a clockwise direction. Now.. if you put in a serpentine belt, it could be reversing the direction of the fan.
Only thing I can think of!
If you have an electrical fan, remove the mechanical! It just puts drag on your engine, and with an electrical fan (or dual fans) you don't need the mech. fan.
Only thing I can think of!
If you have an electrical fan, remove the mechanical! It just puts drag on your engine, and with an electrical fan (or dual fans) you don't need the mech. fan.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by SIXFOOTER
did you put on a serpentine belt kit? thats about the only way I can see the mechanical fan running backwards. If you did, just lose the mech fan
That's what I was thinking. If he built this motor, it could only be two things. Wrong fan for the pump, or wrong pump for the fan. Either way, something else would have to be noticed. A wrong fan could work on a proper rotation engine. The wrong pump would still turn the fan the wrong way because the belt and engine rotation dictate it's rotation. In that case, of the wrong pump, the fan would spin the right way while the engine over-heated because the pump was not flowing correctly. I think he has a fan from a reverse rotation setup, like a serp fan, on a non-serp motor...or the other way around.
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Thread Starter
Racer
Joined: Feb 2005
Posts: 373
Likes: 1
From: Bayonne NJ
I doubt that it is an aftermarket water pump.. I got the universal fan from autozone who in my town could screw up a cup of coffee. But when i bumped the engine to see which direction the fan was spinning it was turning counter clock wise if you were sitting in the drivers seat looking at the engine.. is this right? I took off the mechanical and it is running cooler but i will still need to run a larger fan.. maybe like a 16" i think im running like a 12 or 14. not to sure
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by BanGnGearS
I doubt that it is an aftermarket water pump.. I got the universal fan from autozone who in my town could screw up a cup of coffee. But when i bumped the engine to see which direction the fan was spinning it was turning counter clock wise if you were sitting in the drivers seat looking at the engine.. is this right? I took off the mechanical and it is running cooler but i will still need to run a larger fan.. maybe like a 16" i think im running like a 12 or 14. not to sure
I'm pretty sure you have the wrong fan. A mechanical fan will almost always out do an electric. I would suggest taking the fan a referance, and finding a correct fan, from a different location. Ebay, ZIP, Corvette Central, Echlers, Mid-America, Paragon...to name a few.
Burning Brakes
Joined: Jul 2006
Posts: 1,047
Likes: 12
From: SoCal
with Twin Turbo.Same thing happened to me - the local speed shop got me the wrong fan (the blade pitch made the fan a pusher instead of a puller). Luckily, I didn't have any cooling problems - in fact, I ran the car that way for several months with no problems, but I ended up replacing the fan with the correct Flexalite flex fan.
Thread Starter
Racer
Joined: Feb 2005
Posts: 373
Likes: 1
From: Bayonne NJ
its a flex fan.. but i took the AC out of the car when i rebuilt the engine because the compressor was seized up.. its gotta be the blade pitch that they gave me.. im runnin ok temps with just the electric fan on but after a while it'll run around 235. still to hot..
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
man, first get rid of the flex fan, they do NOT move as much air as the stock fans not to mention that flex fans have a tendency to break off blades and when they do they like to take large chucks of fiberglass with them.... 
. you are better off replacing it with the stock fan and fan clutch.
Also, as long as the fan is turning in the correct direction you may have installed the fan backwards so that the pitch of the blades is wrong as Twin Turbo mentioned.
. you are better off replacing it with the stock fan and fan clutch.Also, as long as the fan is turning in the correct direction you may have installed the fan backwards so that the pitch of the blades is wrong as Twin Turbo mentioned.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by BarryK
Also, as long as the fan is turning in the correct direction you may have installed the fan backwards so that the pitch of the blades is wrong as Twin Turbo mentioned.
FAN BLADE 101:
The direction of the pitch will not change if the fan is removed and mounted backwards. It'll still blow the exact same way.
Thread Starter
Racer
Joined: Feb 2005
Posts: 373
Likes: 1
From: Bayonne NJ
Yea the blades will still direct the flow in the same direction if the fan is reversed. I think i may just buy a larger electrical fan and run that an then hook up the aux fan in the correct manner to a t-stat switch.