Hi I guys I have a question regarding converting from a traditional fan to dual electric fans. I have a regular 16 inch fan as well as a large aluminum rad on my chevy 292 straight six. the fan does a decent job when the cars moving but if I sit for a while the temperature starts to creep up, at which point I put the heat on to pull heat away from the block. I would prefer not to have to do the heat thing and was just wondering wether having dual electric fans would help with keeping the rad ad block cool was worth it
How far does it creep up? Does it just go up and stop? or keep going up? You might not have to do anything, you really need to get some temperatures and work from there. I have a similar set-up as you, and just run the biggest fan that would cover the most of the radiator, only because I have no room for an engine-driven fan.
Is the radiator sealed on all four sides, so air coming through the grill must p*** through the radiator? Does your current fan have a shroud? Are you using the distributor vacuum advance connected to manifold vacuum? All contribute to cooling at idle.
If it creeps at idle I’m guessing your water pump is not moving enough coolant. An ez way to check is lower the level while cool about an 1” in the radiator, leave the cap off and start the engine. When you’re sure the thermostat is open look to see how much coolant is moving. If not much raise the rpm about 100 rpm, if it moves a bunch more you need a smaller pump pulley or larger crank pulley. This was never a problem in the past but today’s gasoline formula runs leaner and causes heat we didn’t have years ago… Solved my problem on a different engine. Also with an electric fan there is more load on the electrical system also causing more heat. I like a shroud and mechanical fan.
On my car I run both a mechanical fan and a pusher fan in front of the radiator connected to a temperature switch. Paranoid about overheating.
I recently switched out a 18" flex fan for 17" solid blade steel fan from Vintage Air. At the same time I replaced the water pump pulley for a smaller diameter, this was on my '37 Chevy truck with a 250 inline six. The new fan and smaller pulley cured its heat problem of creeping up at idle with A/C on. The new fan pulls twice or more air than the flex fan did. It is noisy going down the road, but I'am getting used to now. It cools so much better I might go back to the bigger water pump pulley and see how it acts. I used a V8 Chevrolet pulley made for a long water pump, got it off eBay for cheap. The Vintage Air fan has the mounting plate center of the blades, so half the blade is in front and half in back. If you are cramped for room, this may help. If you go with with dual fans, get the biggest ones you can to cover the most core. A large two speed fan might be a better choice.
The most important thing with a fan, whether it be mechanical or electric, is that the core is covered and the ends are close. If all the air does not go past the fan(s) you are losing opportunity to cool it. If you have a mechanical fan and shroud the fan needs to be in the right place in the shroud. I'm not a fan of flex fans, I have seen what happens when 1 comes apart. There are some pretty neat 2-speed electric fans out there. All OT of course. 90s Taurus has one for the 3.8 and a smaller one for 3.0. Some 90's Volvos use the same fan and motor as the Taurus but have a shroud that is easier to work with. Lincoln Mk VIII are popular. There are GM and Chrysler ones too that work. (IROC Camaro, late C4 Corvette, Jeep Wrangler.....).
I agree with the shroud advice. If there is not enough initial timing advance low speed cooling is affected and gives the symptoms in the original post.
True, but they're cheap and plentiful at junkyards. The Silverados and Tahoes have dual 16" brushless PWM fans in a plastic 1-piece shroud. If you get the whole deal, you'll have an extra fan as a spare. You'd need a custom mount/shroud, but there are aftermarket companies that sell these specific for these fans. There are tons of other OEM application PWM Brushless fans out there in single or dual configurations that would work as well. Volvo, Camaro, Corvette, and several others. There's just not as many options for aftermarket mounts for them. You could always fabricate a mount or even modify a stock shroud to work. Brushless PWM fans are quieter, last longer, and are more efficient so they don't tax the charging system when on. With PWM control it can be fine tuned to operate at the speeds you want based on coolant temperature, etc. I'm using a dual 16" Silverado PWM fan ***embly in the OE shroud with an OE Silverado radiator in my '56 F-100 and it's all controlled and tuned by the Holley EFI. I want OE reliability and accessibility if the parts ever need to be replaced.
Here is an '00 Contour dual 2-speed fan setup on a '69 Mustang radiator with 16x24 core. That size radiator could probably be used in a bunch of on topic cars. You can see that the fan is pretty good on width covering the core. Could have used a little something up and down to really seal it off. It is nice and low profile too. I too like OEM fans instead of aftermarket so I can buy a motor anywhere there is a parts store or junkyard if I had to have one. There are writeups on using OEM type sensors and controllers so you don't need an expensive aftermarket controller for a 2-speed fan. I also have an '03 Lincoln LS fan that was really nice but you pretty much have to use the stock LS radiator with it. Those radiators are not available with coolers for an automatic trans. It has a soft start so not a huge amp spike and could be wired without a controller. It is single speed but really moves some air-and is relatively quiet.
hi guys thanks for the responses as for how quickly the temperature goes up at idle it goes up roughly a degree per minute. the fan is totally open because i moved the radiator forward making using a stock fan shroud not possible. I think I'm gonna try making my own shroud and try to install a slightly bigger fan and see if that works just cause after doing research into installing duel electric fans and all the parts necessary for the conversion its gonna be pretty pricey when I covert it to canadian dollars. Again thanks for the help
You say you moved the radiator forward... How much space do you have between the radiator and the fan? If there is too much gap the fan will not be drawing air through the radiator, especially with no shroud. It will just be ****ing air in from around the edges. No bueno, especially at idle.
Years ago I had a 47 Chevy with a 350 and when I would cruise the shows it would immediately start to heat---180 to 230 so I put an electric pusher on the front of the radiator activated by a switch under the dash. Cured the problem. Only used the electric fan when criusing at low speed or idleing in traffic.
Here is my suggestion.... Make a shroud that lets you mount the fan with the blades in the hole/or inside slightly so the fan can NOT draw air sideways across the back of the shroud. All air should come from ahead of the fan and inside the shroud. Insure that the four sides of the shroud actually seal against the radiator or you will be drawing quite a bit of air from behind the radiator and cut down on what p***es thru the radiator. I made one that has a folded lip on top and slips down th hang it. On the bottom I have a couble of clips that let me draw it against the radiator. On each side the shroud has a folded edge that I can put double sided foam tape on, nd as I draw it against the radiator the foam strips seal the sides. Eliminating the loss of efficiency by insuring the shroud seals pretty well shoul help, especially when idling.
99.99999999% of overheating problems are air flow problems. I use Lincoln Mark VIII, 2-speed fans on my builds. always available on ebaY. They have their own sort-of shroud, just takes a little fab to fit on your radiator. I've made the m both push and pull. Fits '59 fan shrouds perfectly!
The blade design reminds me of when the owner of the company wanted to tool up an 11” dia condenser fan for our mobile HVAC units. We tested all kinds of blade designs and found that a forward curving blade design with a width greater at the tip moved the most air with the least amount of power, with the least amount of noise. This was in the mid 90s. Haha!
Yes, these factory fans blow all the aftermarket ones totally away!! I found the 2-speed controller on an internet search.
I'm not sure what you are running the 292 in but on the 250 in my 48 with that size of fan the fan covers less than half the radiator core area and if you don't have a shroud to pull air though all the core with the temp gauge goes up exactly as you describe and will drop down just as fast when you get above 20 mph and get air flow to the whole core. And yes I am the fool that drove that truck well over 200K over the years and maybe more than that with no shroud watching the temp gauge at a lot of stop lights.
I run a 16" spal puller fan without a shroud, mounted with a 3/8" gap to the back of the radiator, did this on a few builds, never overheats.
You can do 2-speed fan control pretty cheaply. All OT parts but pretty readily available in pick-and-pull yards. Various 92-04 Volvos have a 2-speed relay and 61318361787 is BMW temp switch from 92-99 318 and 96-02 Z3. The settings are 180/195F. The BMW switch is M14x1.5 thread. I bought a radiator hose connector that had this thread on 1 project and on another project, I bought a 3/8 to ¼ bushing and drilled and tapped it M14. You need both of these with the junkyard pigtails because the plugs are unique. But for like $25 you can have reliable 2-speed fan control. Wiring diagrams are out there with a search. I know this setup is way OT with German and Irish parts, but It's just as good as an aftermarket controller that was made in China and you can hide it. If you need electric fans it's something to consider.
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