Electric cooling fan

[40 Chev Coupe]

Looking for a electric cooling fan for my Merc, I have a 16" Zirgo right now and dont seem to get the job done. I dont have room for a mechanical fan. Looking for a dependable and high cfm, any suggestions? What works for you?

[wayne petty]

a few things..  and i know nothing about your current installation. this is just 3 am stuff..

relays..  to power the fans..  as close to the fans or positive power source.. so you have less voltage drop which will take the speed and cooling abilities from your fans..

you may want to measure voltage drop with your current fans..  with them operating at max speed...

meter set to 20 volts DC..  measure between the positive battery post and the  positive wire into the fan motor..  you may want to use a thin very sharp pin so the insulation will self heal..  you can usually back probe the fan connectors.. but do it on the fan motor side of the connectors.

then do the same test from the negative battery post to the negative fan wiring.

with the amp draw of fan motors.. i would like to see less than 0.3 volts  less is better.. that is over 1/4 of a volt.. this is done engine running.charging system over 14 volts. . headlights on.. and the fans running..

you may want to perform this test first.. to check the rest of your electrical connections in the car.. http://i.imgur.com/WMDprhm.jpg  

if you have a rear battery.. front engine.  use a single jumper cable laid on the ground under the car as an extension to the negative battery post for tests 2 thru 4.. and to the positive battery posts for test 5 and 6.

these are just early morning rantings..

i am hoping that you are also running a thermostat and the cooling system is equipped with a bypass circuit.. so the water pump flow goes thru the block. up the back of the heads.. into the intake crossover where its blocked by the closed thermostat.. forced thru the 5/8" bypass hose and back into the water pump or lower hose where it can get pushed around thru the block and heads until it has picked up enough heat to open the thermostat..

at that point the coolant will swap.. the cooler coolant will close the thermostat and the hot coolant in the radiator will cycle the fan switch on to turn on your electric fans..  when the fans have cooled the stationary coolant in the radiator enough.. the fans cycle off and await the next swap of hot for cooler..

at highway speeds the heat build up will result in a partially open thermostat..  which is totally normal..

if your thermostat temp is too cool ..  there may not be enough temp differential to allow the ambient air to reduce the coolant temp in the radiator before the thermostat opens again..

when this happens.. its a run away cooling system.. the coolant gets hotter and hotter.. the thermostat opens farther and farther.. the water pump moves the water thru the radiator faster and faster never slowing down enough to cool any.. but at some point  the water flow from the pump can exceed the flow abilities of the radiator.  this can really effect large top tank radiators.  the flow against the resistance can expand the top tank and blow the top tank solder joints or crack the top tank..

[jaybee]

40, are all the right panels in place to make sure air can't circulate from inside the engine compartment to the front of the radiator? Seriously, it doesn't take much to create a situation in which you're pulling hotter and hotter air through the radiator. I watched a 370hp diesel generator do that inside a brick enclosure with open top and an opening in front of the radiator. On these units air is pulled in over the generator and exits through the radiator. Even with a hole in the wall the same size as the radiator enough air failed to exit the enclosure that the unit would shut down in about 10 minutes. A sheet metal duct from the radiator opening on the unit to the brickwork fixed it so the generator would run all day long in 100 degree heat.

Wayne, how does a fully modern cooling system with pressurized degas bottle change what you've described? Such a system still has a bypass, but it also has connections from the heads to the degas bottle and degas bottle to the hot side of the radiator. It seems to me there ought to be some level of circulation involving that as vapor comes in through and the block & heads need to have that volume replaced.

[papastoyss]

If your electrics are in order I like the Cooling Components self contained fan/shroud unit. They do require a 70 amp relay. I use the adjustable sensor w/a probe in the radiator to ground the relay to turn the fan on & off.

[wayne petty]

40,
Wayne, how does a fully modern cooling system with pressurized degas bottle change what you've described? Such a system still has a bypass, but it also has connections from the heads to the degas bottle and degas bottle to the hot side of the radiator. It seems to me there ought to be some level of circulation involving that as vapor comes in through and the block & heads need to have that volume replaced.

many cars with the remote pressurized coolant reservoir have a small hose that feeds the top of the bottle and bleeds the system of trapped air/steam bubbles.

all engine cooling systems have a bypass or they will overheat..

the thermostat is almost a foot from any heat generating parts..


with the weird cooling system and heater systems it gets to be a challenge to identify the bypass circuit..  but its always there..

Fwd mopars had an issue in the late 80s.. that they used an H shaped heater control valve.  when the heat was off..  the heater core flow was stopped.. the coolant flow was directed directly back to the other hose.. but because the flow stopped.. the heater cores clogged.  when the heater control valve was activated.. the coolant bypass circuit was blocked by the clogged heater core and the engine would start to over heat..

chevy trucks and a few other GM cars had a weird design..  the heater core flow went back to the radiator tank.. but if you looked closely it went to the bottom tank.. the side that fed the lower radiator hose..   so the coolant was circulated thru the block. heads, intake. heater core.. bottom tank of the cross flow radiator.. lower radiator hose water pump and around again.


when the water pump is turning there must be coolant flow past the thermostat.

there are a few things i did not mention as it was the middle of the night..

because the bypass is smaller diameter than the amount of coolant flow the pumps can move.. at highway speeds..  the pump is working hard and building mechanical coolant pressure in the block and heads above the radiator cap pressure. this increases the boiling point of the coolant in the block and heads.. this stops the hottest areas around the exhaust valve seats.. the spark plugs and the exhaust valve guides from boiling..

somebody reading this should really produce this idea..

ever seen a front wheel drive 3.1 /3.4 GM motor.. where the water pump is moved out in front of the left head. so the engine will fit in the narrow engine bay..   imagine building an eyebrow shaped coolant passage that bolts to the stock chevy water pump mounting points. that moves something like the 3.1 water pump out in front of one of the heads..  a whole new short pulley set would need to be produced and some way to mount the alternator..  this could really free up front end space for hot rod installations..  make more room for electric fans..

i have been meaning to go over to edelbrock and talk to them about it but up till recently .. i had no good way to get there.

[Topsterguy]

I like Pappastoys idea - I used a Coolinf Components setup in my 40 and my 32 and they worked great......very nice unit overall.

[kb426]

I'm a Cooling Components guy also. I used a Centec adjustable controller that takes it's signal from the temp gauge.