COOLING PROBLEM- What works best to cool a radiator without a mechanical fan? A- An electric "PULL" fan? (between the radiator and the motor). OR B- An electric "PUSH" fan? (in front of the radiator). Thank you in advance...............
pull. why have that big old electric motor out front blocking that nice cold air from getting to the radiator.
Pullers are about 20% more efficient than pushers. A puller draws the air in at any angle and around obstacles like a vacuum, pulling the hot air from the radiator at a constant CFM. With a pusher the air is pushed towards the radiator and this causes some bounce where it loses 20% of it's flow. Additionally, a pusher will impede air flow through the radiator while driving.
My su****ions were right on the money. I recently purchased a '40 Chevy coupe with a 427CI motor. The fan is placed in the front of the radiator. The fan is a 1700 CFM ............... When I got the car, I flushed the system and replaced the 180 thermostat. The car still tends to climb above 180 even when travelling at speeds of 50+ mph. The fan and radiator are old and will be replaced soon. I will be installing an alluminum radiator with the highest CFM puller fan possible. May even install a shroud if need be. Thanks a bunch for all the quick responsce .............. LG, Mike
I've had a mechanical puller, then a pusher on the same motor, you can probably guess which one worked best switched to a dual electric puller and I'm happy as can be
Mechanical first if possible. then a puller last resort a pusher. Like X38 said why are you worried at 180 ?
Does it boil at idly or in traffic? If it is climbing with the air flow of highway speeds like Joee said you may not have enough radiator. I would recommend a shroud no matter what, one of the issues you may be having is the fan drawing hot air through the radiator from the engine compartment. Its not an uncommon issue and you may not need a new radiator. If you do go with a new one, go with br*** and copper. They cool better and are infinitely more repairable. Doc.
Pull. Puller fans create a slight (or more than slight) drop in air pressure at the radiator, which results in a slight drop in temperature and, hence, a slight increase in the air's ability to absorb heat. It's Boyle's law on a small scale. Moreover it's unusual to see a shroud on a pusher, as it would be an obstruction when the fan's off.
The Radiator doesn't have enough capacity is why the temp climbs as you go faster....Found that out on my model a Highboy I had a pusher mounted on the front of the radiator behind my 32 shell for 10 years and only had to use it a few times. Nothing beats a GOOD radiator... never ran a Mech. fan or a shroud
Everything I have ever read says use a puller, BUT: 1. That puts the fan motor in the direct path of all that heated air, which must cut down on the life and efficiency of the fan? 2. If the fan isn't nicely shrouded it's only pulling air through the diameter of the fan itself, whereas a pusher fan is blowing air at the radiator whether or not it's perfectly mounted So for that reason I put a pusher on my car as an auxiliary and it works great despite being pretty small and mounted in a less-than-ideal spot on the radiator. And S****s is right, if the temp is climbing when the car is moving the weak link is the radiator. If it climbs when the car is idling it's mostly the fan.
Also, make sure that the radiator bracketry is sealed up so that all the air going in the grille is going through the radiator.That will help out on the highway. Another thing is to make sure the air can exit the engine bay. Not really an issue for open engine cars, but can be for fat fenders and 32's with no louvers.
I use a Spal 16" pusher, 30 amp fan, an aluminum radiator, no shroud on a 351W, I had to raise my stat to keep it warmer in the fall, engine never gets over 180, in some cases you will have a clearance issue that requires a front mount pusher fan. Stand alone, off of the car, the fans push and pull the same cfm, mounted to the car they will have the exact same surface exposure to the radiator face of the radiator, the area of blockage face and back of the radiator is the same as caused by the fan body. Mechanically pull and push will work the same in a non moving vehicle. Factors that could change this would be obstruction to the air path into or out of the fan. If the vehicle is in motion, the surface area of the fan and shroud would cause an airflow blockage prior to the fan activating by preventing free airflow. Once the fan kicks on at speed that effect is minimal. You do not even need to mount the radiator at the front of the vehicle with an electric fan, you need to keep the overflow tube as the highest point on the system. Using a puller on the front and a pusher on the back does not double your airflow cfm, you will achieve a maximum allowed velocity due to restriction and drag. In most cases where an older vehicle is over heating it is due to poor heat exchange in the radiator, blocked tubes.
i've always been told that pullers are more efficient than pushers. think about it , there must be some reason about 99.999999% of propeller aircraft are pullers
Hi, I am being forced to use an electric fan in my 1952 Plymouth wagon due to no clearance left between the early hemi and the radiator. I am buying a Mark VIII fan to use. Question is, does the fan care whether it pushes or pulls? Can this fan be used either way? Jan in Ojai, CA
Sure: THEY aren't pulling 220-degree air! I do believe pullers are more efficient when everything is ideal, but my own experience tells me it's not much of a difference and we worry about this too much. Pushers seem to work fine for everyone I know that has one; that's all I'm saying.
I always thought that pullers were the way to go and when I fitted the custom grille to the Plymouth I found that the airflow was restricted and she was getting a bit warm.I got a 16" big cfm semi shrouded fan and found that even with just the pulley bolted to the waterpump, there wasn't quite enough room for the fan. So I made it a pusher and wired it to a very small (think matchbox)electronic fan controller.it's set to 90deg C and you have to be idling or in traffic for a while on a warm day for the fan to kick in......car runs at about 77 deg C at 100 kph (60mph) The radiator is renewed original with a 180 thermostat and the fan cured my problem.
As posted earlier, make sure air has good exit from under hood. I use 2 - 10 inch push fans. They never come on as long as the car is moving. At idle on a hot day fans come on at 195, takes about a minute to shut down at 185. Puller usually looks better though.
My cars engine compartment is a pizza oven,tryed just about everthing,have dual fans that draw over 40amps when running pull about3000 cfm,alumn rad,front airdam directs air thru rad.Fianly got air to move out by louvers in hood and louvers in fenderwells.Some times you need to restrict fluid going tru rad to slow the flo down to let the fans do there job.I don't remember if you stated what compression is used in motor,plus sometimes where you put the temp probe could affect what you are reading.I would suggest a laser temp gun and actually check if you are really running hot.If you are not boiling over at idleing for a while you may be alright.So many factors determine temp in motor.I run 175 at idle and 180 when running at 70. 10.5 comp.Hope this helps Rogue
Thank you very much for all the input on the fan issue. MY BAD, I'm elated at 180 degrees............what I meant to say is that on highway speeds it jumps up to above 200 and when it does it does NOT go down. I'm in the process of replacing the radiator and have no choice on using a pusher fan....I have clearance problem. I'm also going to use a higher CFM pusher fan.............. Thanks again, Mike
at highway speeds your fan shouldnt be doing anything. The air moving thru the radiator at 50mph is moving faster than the fan can pull it anyway. You should be looking elsewhere for a cure.
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