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Adding Pusher Fans - Circuit Help ?
Hi Guys:
I have a set of twin pusher fans that came with ERA #375. These are the type that mount in front of the radiator. At present, my ERA has the splitter wing in the nose and a single large puller fan behind the radiator. I am aware that the wiring harness accomodates both the puller and pusher fans. However, I would like to set up the new pusher fans on their own independent circuit with their own flip switch. I really do not want 3 fans running for about 6 minutes when I pull into the garage after a run. Am I being too cautious about having 3 fans running? Bob, what is the best way to wire these fans independent of the puller fan? I just want to turn the pushers on or off with a switch, with no thermal switching activation (via the water temp switch on the puller fan circuit). What is the best way to protect the proposed new circuit with a fuse? Can I use an existing fuse? Should I use a fan relay? What are the pros and cons of not using a relay? Sorry for all the quesitons, thanks so much. Cheers, |
Art,
What I did with mine was run all new wire. I used an in-line fuse, and mounted a new relay near the front. Then I took the power through a toggle switch on my dash. You can either use switched power or have it hot all the time in case you want to run the fnas while the switch is turned off. It has worked great for 8 years. I also drew a schematic and keep it in my book showing all the connection points and wire route. Ron :) |
One option is to wire a kill switch in the low amperage relay circuit. Thus when you shut down the motor you have the option to allow the fans to run until the coolant temp drops or flip the switch to kill the fans immediately. Another option is to wire the low amperage current thru the relay from the ignition switch. That way when you shut off the ignition, the fans will shut off also.
Rupert Hartmann |
The above advice is all valid. Personally, I would install a second relay that got its main power from fuse 3 and its pull-coil power from the hot lead (the wire that goes to the main fan) of the first relay. Run the other side of the relay pull-coil connection through the new switch to ground. You'll end up with front fans that only run when the rear fan, the ignition, and the new switch is on.
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Thanks Bob, and guys, those are great ideas. This will be my next rainy day chore. I may have to stop by ERA someday soon to pick up a matching switch. Seee Yaa!:D
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I am curious about the utility of running the fan when the engine is off.
My feeling is that you will receive only a minimal benefit of running the fans after shutdown since the only coolent circulation will be a small amount of cooler water in the radiator flowing from the bottom hose back to the engine block. Or is it the hot water flowing from the engine to the rad via the upper hose thus cooling the heads a little that justify using a fan after shutdown? I have always been puzzled why the car makers bothered with it. Now, fans and an electric water pump would be a different story. John |
John,
For the most part you are correct. My fans push so much air through even at a stand still that it hits the engine block and heads. Just that movement of air is a help but I hardly ever turn them on once the car is stopped. Normally I just let the engine idle for a minute or so after I stop with the fans going and then shur it off. Ron |
Besides cooling the block a little, we keep the fans running for a while to reduce fuel percolation in the carb.
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The early cars first cars ever made did not have water pumps but used only coolant to keep the engine cool. This was done by using a larger rad and letting the cooler water flow into the engine by the hot water rising to the top. Running the fans after engine shut down will do the same thing till the stat starts to close if you run it that long. We set up our cars to run till the temp sensor on the fan drops below the pre set temp and breaks the relay.
Helps cool the engine for easier starts and does cut down on boiling fuel out of the carb on those hot Florida days. The way we set them up you drive the car, shut it of after your trip and if the engine is to hot the fan will run till it cools off. Jump back in after your visit and go with a engine that is not heat soaked. |
Fellas,
I'm not a "fan" of running fan[s] after shut-off for fear of battery weakness. A five minute, big amp draw, drain in hot weather is asking for trouble IMHO. I also run MSD and fuel pump which keeps my Optima plenty busy, but my alternator works well. Am I wrong to worry about fan running without charging? Thanks, |
Maybe I'm a little cautious, but I keep thinking the exposed pushers running when I'm not there (on a sensor) is a liability. I'm thinking of putting on pushers, but only the fan under the hood will run on a sensor.
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The fan only runs for a few minutes and will not cause any harm to the battery. Again here in Florida were it can be in the 100+ range in the summer it works very well. Never had one of our cars not start due to our fan set up. If some of the big three can set up there cars in a way much like we use and not have a problem with all of the new electrics on those I do not see the problem.
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A fully charged battery has approximately 60 amp-hrs capacity. 25 amps x 5 minutes absorbs about 3% of that.
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To ease your feelings, why not just run the relay off of the ACC.
That way the key would have to be on to have the fans run. Just a thought |
Hi Bob:
Do you know how many DC Amps the single puller fan (mounted) behind the radiator draws? Mine is circa, 1992 - ish as my ERA is number #375. The only insignia on it says "Made in Canada" from what I can see. It is a single fan with paddle blades connected to a circular rim (which turns with the blades). Reason I ask is that I am wondering what the total AMP draw will be when all 3 fans are humming along? My Bosch Fan Relay is a number 0 332 002 156 which I think is a 30A relay. I suspect I will be okay with all the fans on one circuit. My particular fan wiring does not have the auxiliary pusher fan plug up front for the pusher fans. Maybe you guys added that feature to the harness after my car was made or perhaps it was removed? However, adding that to the existing wiring would be easy to plumb up. |
Red,
The standard fan of that vintage drew 15-18 amps. The front fans draw 4-5 amps each. We haven't had a problem using the 30 amp relay with all three fans. Even our optional fan that draws about 20 amps seems to be OK with the front fans. The wiring changed some time after your car to have two plugs coming out of the main harness, but I changed the system back to a single plug a couple of years ago. Now I include the "jumper" in the front fan harness. 'Makes the system cleaner when the front fans aren't installed (and saves me work, too :rolleyes: ). |
New Single Puller Fan Set Up
Bob, I understand that ERA has a relatively new single fan puller set up. Can you share specs or a picture / diagram of this fan and mounting brackets? Next I want to convert my puller fan mounting system (plastic tabs thru the radiator) to some configuration of metal brackets. New hub carriers installed and back on-line!
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The newer mounting system looks like this:
http://www.erareplicas.com/427man/cooling/radmount.gif I think that the stud spacing for the upper and lower mounts is the same as the brass radiator mount, although you may have to space the fan to adjust the distance to the radiator. Give Peter or Fernando a call for pricing. |
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