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TR2/3/3A Pusher Fan Again....Direction of airflow.

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K

karls59tr

Obi Wan
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I have a yellow TR6 fan mounted backwards that replaces the stock fan. I have a Pusher fan mounted "in front" of the radiator that I turn on by toggle switch when it's really hot out and I'm in bumper to bumper traffic. The car does not overheat and the temp gauge reads 160 degrees in day to day driving.
Today when the car was idling I put my hand in front of the grille and noticed that the electric fan is pulling air away from the radiator and out thru the grill. Is the electric fan supposed to be drawing air from outside the grille and "pushing" it thru rad as the name implies? In other words should I switch the wires around so that air is blowing thru the rad towards the engine?
Mild dsylexia issue here:friendly_wink:....if the electric fan was on when I was doing 60 on the highway(not that it would be needed) would it be fighting the Tr6 fan in terms of direction of airflow?
 
Sure sounds like the polarity is backwards on that electric fan. A reverse airflow would, at best, be inefficient and under most circumstances counter-productive.

Probably just a matter of swapping the leads (Hot & ground) to turn things around.

Many electrics also have blades with slight airfoils (curved in profile) that work more efficiently of they are correctly oriented. To change that (if necessary) you would have to remove the blade and flip it over (this does not change the direction of air flow). The curved profile (if it is there) is like the surfaces of an airplane wing and you would want the 'top' of the wing profile to be towards the front of the car. Most electrics are shipped with the expectation they will be pullers so if no one has messed with it then it quite possibly needs the blade flipped. Again, that is for optimum performance - it will still move air even if mounted 'backwards'.
 
tdskip said:
Do you want anything in front of the cool air flow?
Click to expand...

I guess the body of the electric fan does block some of the incoming cool air but I wanted to have an extra fan for hot weather traffic jams. The way the front cowl is on the TR3 the part under the grille blocks about 1/3rd of the rad. I cut four 2&1/2" holes there with a hole saw to get airflow to that part of the rad. Put some black mesh on the inside of the holes to keep debris out.
 
Geo Hahn said:
Sure sounds like the polarity is backwards on that electric fan. A reverse airflow would, at best, be inefficient and under most circumstances counter-productive.

Probably just a matter of swapping the leads (Hot & ground) to turn things around.

Many electrics also have blades with slight airfoils (curved in profile) that work more efficiently of they are correctly oriented. To change that (if necessary) you would have to remove the blade and flip it over (this does not change the direction of air flow). The curved profile (if it is there) is like the surfaces of an airplane wing and you would want the 'top' of the wing profile to be towards the front of the car. Most electrics are shipped with the expectation they will be pullers so if no one has messed with it then it quite possibly needs the blade flipped. Again, that is for optimum performance - it will still move air even if mounted 'backwards'.
Click to expand...

In regard to the TR6 fan mounted backwards....it appears to also be pushing air out thru the rad rather than pulling cool air in thru the rad towards the motor?
 
karls59tr said:
In regard to the TR6 fan mounted backwards....it appears to also be pushing air out thru the rad rather than pulling cool air in thru the rad towards the motor?
Click to expand...

No, flipping the fan over does not change the direction it pushes the air -- like a nut will go on a bolt the same way no matter which side of the nut you start.

Flipping the TR6 fan probably makes it a bit less efficient due to the air foil I mentioned - but not enough to worry about.

I used a front-mounted electric pusher when I had the stock TR3A fan but ditched it when I went to a bigger, more-bladed, more-pitch fan. I no longer seemed to need it and was sure it did block some air flow (motor & blades) when not in use.
 
Not all DC fan motors are reversible by swapping polarity. I believe all Hayden fans are reversible, but the Spal in my TR3 is not. Check with your manufacturer. Also, if the motor direction is reversible, usually the fan is reversed too, especially if it curved.
 
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