Pusher Fan Advice?

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Mike Paradise

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I'm looking for input on a pusher fan, I have a 69 Dart 383 GTS, aluminum heads, intake & new aluminum radiator, everything is new, has a 165 degree thermostat. The car runs like it's supposed to with no overheating issues as long as it's moving along. During slow moving parades it wants to creep up to the 230-240 range so I bail out at the first cross street I can find. I was thinking about installing a pusher fan to be run manually, but there are many options on CFM ratings, The radiator is an 22" aluminum stock replica of the original copper one. If anyone has dealt with a similar situation I would apprceiate your thoughts, Thanks
 
Advice? Figure out what's wrong with your cooling system. A pusher fan is just a band-aid.

If it's overheating when in traffic or while it's moving slow the most likely culprit is an underdrive pulley on your water pump. Not having a fan shroud could also contribute to the issue.
 
Nothing wrong with a pusher fan if that's what your asking, I am using one on my Barracuda with a Wizard radiator that has dual 1.5" cores.......zero overheating issues.
 
Mike, is that a 2 row replica? As mentioned, a shroud and a close fan is necessary for a stock type system.

One other thing i'll mention is, make sure your running as much initial timing as the setup can handle.
 
'68cuda416 said:
Nothing wrong with a pusher fan if that's what your asking, I am using one on my Barracuda with a Wizard radiator that has dual 1.5" cores.......zero overheating issues.
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Of course there's something wrong with pusher fan. Your cooling system shouldn't need it, and it obstructs airflow through the radiator. There are both mechanical and electric fan options that work great standalone. If you need a pusher fan in addition to a mechanical fan to keep from overheating you either aren't running enough radiator or your mechanical fan isn't up to it's job. Both can be remedied and the result is a more efficient system than what you get throwing a pusher fan band aid into the system.
 
For starters not everybody runs a mechanical pump, I am using an electric pump and there is no room for a puller with any kind of substance. Take some advice.......you don't have the power I have and power is heat so just take a step back and work on your stock combos with circus wheels.
 
I assume it's a stock style WP. Keep in mind a hi flow pump or overdriven pulleys can overrun a stock capacity system. Meaning the coolant doesn't spend enough time in the radiator to dissipate heat. Your aluminum heads should help though.

For you other guys...Been a long time since i fooled with a cooling system, is it possible to put fan on backwards? just spitballing here.
 
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'68cuda416 said:
For starters not everybody runs a mechanical pump, I am using an electric pump and there is no room for a puller with any kind of substance. Take some advice.......you don't have the power I have and power is heat so just take a step back and work on your stock combos with circus wheels.
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Well gosh, if you’d actually read my comments you’d see that they’re about running a pusher fan in front of a mechanical fan, which means they don’t apply to you.

And if you read what the OP said, you’d probably have realized he has to be running a mechanical fan and is talking about adding a pusher.

And finally, it sounds like your set up is totally different than the OP’s, and since this is about his car and not yours your car isn’t super relevant is it?
 
Mike Paradise said:
I'm looking for input on a pusher fan, I have a 69 Dart 383 GTS, aluminum heads, intake & new aluminum radiator, everything is new, has a 165 degree thermostat
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Tell us more about your current fan, shroud?, Pulley diameters, type of water pump (number of vains etc.)

I know 2 guys with 383 darts both have stock cooling systems and no overheating issues
 
[1] Post #8 is completely wrong about coolant not spending enough time in the rad. Old wives tale. See link below for tips. Think about this: if the coolant spends more time in the rad, it then means the coolant stays longer in the engine...& picks up additional heat...which the rad now has to cool.
[2] If you have an overheat problem, changing the t/stat rating will not fix it.
[3] Overdrive the w/pump by 10-30% & make sure the impeller blade gap is tight.
[4] The hole in the housing under the stat. You can reduce to about 3/8" diam; it will help cooling because less hot coolant is diverted to the intake side of the pump.
[6] Ignition timiiiiiiiiiiiiiiiiiiiiiiiiiing!!! Make sure you have plenty at idle & 45-60* at cruise. Not enough timing, a sure fire way to cause o'heating.
[7] lean mixture at cruise can also cause hot running, but would have to be veeeery lean....
[8] www.stewartcomponents.com
 
OldmanRick said:
I assume it's a stock style WP. Keep in mind a hi flow pump or overdriven pulleys can overrun a stock capacity system. Meaning the coolant doesn't spend enough time in the radiator to dissipate heat. Your aluminum heads should help though.

For you other guys...Been a long time since i fooled with a cooling system, is it possible to put fan on backwards? just spitballing here.
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NOOOOOOOOO. This is wrong. You do NOT a want the coolant hanging out in the radiator. That is exactly backwards.
 
I had a similar problem. My radiator tubes were expanded on my aluminum rad from a over pressured leak test when made. The air was not flowing through the radiator sufficiently. Just something to check although it may not be your problem. See if you have good air flow with your fan by holding a piece of paper in front of the radiator while the fan is pulling at idle.
 
Water flow can be checked with a gutted thermostat. one inch restrictor hole is what you need that is the correct flow rate. I ran one inch hoses.

Steve 100 (3).JPG
 
Wow guys!! Funny how a simple question can cause such a fuss, let me provide a little more information of the set up.
When the lower end was returned the from the rebuild shop I installed an Edlebrock Performer top end kit which included the heads, intake, cam, etc. The Performer heads have no cooling ports that connect to the block, they are basically air cooled, The radiator is an aluminum exact replica of the original big block radiator for the GTS, the difference is that the original radiator had 3 - 1/2" core tubes and the new aluminum one has two 1" core tubes. The fan is an original 7 blade with the original fan shroud, the water pump is factory original, the pulleys are aluminum but standard diameter size. The issue occurs after about 20 minutes of very slow moving parade traffic.

P1170502.JPG


P1170501.JPG
 
Mike Paradise said:
Wow guys!! Funny how a simple question can cause such a fuss, let me provide a little more information of the set up.
When the lower end was returned the from the rebuild shop I installed an Edlebrock Performer top end kit which included the heads, intake, cam, etc. The Performer heads have no cooling ports that connect to the block, they are basically air cooled, The radiator is an aluminum exact replica of the original big block radiator for the GTS, the difference is that the original radiator had 3 - 1/2" core tubes and the new aluminum one has two 1" core tubes. The fan is an original 7 blade with the original fan shroud, the water pump is factory original, the pulleys are aluminum but standard diameter size. The issue occurs after about 20 minutes of very slow moving parade traffic.

View attachment 1715885049

View attachment 1715885050
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What are standard diameter? There were many pulley combinations. Most aftermarket pulleys are garbage.
 
The speed of the circulating coolant is not a factor unless it's not moving (thermostat closed or restriction somewhere). Since it's a closed loop system with one pump, the velocity of the coolant is the same in the engine as it is in the radiator. It's on both sides of the equation and therefore cancels out, leaving surface area vs. surface area. The surface area in the engine is basically fixed, as is the radiator. So the only two variables you can really change is the amount of heat going into the system or the amount of airflow through the radiator. But even then airflow is only a factor if it's way too slow.

Since your temperature begins to creep up in low RPM/low airflow situations, it seems logical to increase airflow a bit. As you indicate, getting the car moving a little faster brings the temperature in line. If you put it in neutral and idle up to 1500-2000 for a minute or so, does the temp come down? If so, then a booster fan might help. If not, then it may be a matter of getting the heat out of the engine compartment, not just the radiator. Ideally you would monitor the temp in the upper and lower radiator hoses (and underhood temp) and see what's really happening. If the underhood temp climbs in parallel with or faster than coolant temp, a bigger fan might not be much help

The drawback to pusher fans is they pose an airflow restriction once you are moving which gets worse with vehicle speed. No fan manufacturer is going to recommend dual (push and pull) fans. The best solution would be to remove the 7-blade and install an electric on the engine side with a manual override switch. Or better yet, avoid parade speed traffic.
 
And think about this.
Performance alum heads have bigger ports, with plenty of extra metal for additional porting. The decks are usually 9/16" to 5/8" thick, compared to about 3/8" for iron. Valve spring pockets need to be thicker because alum is not as strong as iron. Likewise with the alum surrounding the head bolt bosses, accessory holes.
All of this intrudes into the coolant passages, reducing the volume available for coolant.
 
I also notice that the fan clutch is missing. Put it back on. Since you no longer have a stock engine, the stock cooling system may not be adequate. Agree, 190° Thermostat and back off the timing when you are in a parade...Fans do nothing after about 45 MPH. Fans do everything below that speed, you need airflow through the radiator and especially if you have a/c. The condensor blocks airflow on cars with a/c
 
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