The Stovebolt Site Forums The Shop Area Engine Shop Noisy Electronic Radiator Fan

Hey all,

Am finally getting my 1950 Chevy 3100 running and have a question. This is my first vintage truck and the radiator was replaced by the previous owner with an aluminum radiator and electric fan, and this is my question.

When I turn on the (ignition) key, the radiator fan immediately starts whirling, rather loudly. According to a spectrum analyzer app on my phone its whirling at around 1800 rpm, which seems normal according to the forums posts I reviewed here. However the noise is so loud it rivals the engine noise when I start it up. Is this normal ?

It would seem to me the fan would be wired to be off until the temperature sensor reached say 180-200 degrees and then turn on, sort of along with the thermostat. Now the temp sensor in the engine, a 1960 vintage 261, still uses a liquid I guess it is, mechanism for indicating temperature on the dash gauge. Perhaps this prevented the fan from being relayed switched to only turn on when the engine got hot ?

Any guidance would be appreciated... all my experience is with fan belt driven fans, so learning curve for me on this one :-)

thanks

It won't hurt anything for the fan to run with the ignition, but it is super annoying.

There are controllers you can get with a probe that goes into the radiator to check the temperature and control the fan. That way you can leave your stock gauge alone.

https://flex-a-lite.com/adjustable-temperature-electric-fan-controller.html

This one is fairly expensive, but flex-a-lite traditionally makes a good product.

The stock temperature gauge and sensor operates mechanically.
Your electric fan may have a separate sensor that is attached in some method to the aluminum radiator.
You would have to identify which fan you have and look for the manufacturer's information on their website.

I would put a mechanical fan on it.

When mine was installed it was wired to come on with the ignition switch but I had it rewired to a switch under the dash.

I second Carl's suggestion. Put the mechanical fan back on or even a hydraulic clutch type fan. They're quiet and provide all the cooling that truck needs.

Joe, for a different opinion I like the electric fans...a lot. If you live in a place like Dallas where we have hot weather, slow (sometimes stop/go) traffic and you also have A/C, you need more than you'll get from a stock fan and a thermostatically controlled electric fan is a good answer. Plus the stock fan I had was out of balance...enough out that it would cause the water pump to fail about every 2 or 3 years. Predictably. Whether I had a bad one or whether this is just an unavoidable problem with these I can't say, but removing the fan from the engine makes more sense to me.

Thanks all for the comments, indeed this truck was restored in Dallas area, which is perhaps why the electric fan was used. My area is also typically in the mid 90s in the summer, but less slow traffic... but the controller mentioned by Fibonachu seems the right answer for me. I found a TorqFlo thermostat/switch at Auto Zone (733653) that seems ideal for my application, and it was a little cheaper than the Flex-A-Lite referenced (about $16). (see picture of contents).

The TorqFlo has a unique attaching scheme it seems, it uses like a Ty-Wrap type plastic "wire" that you push thru the radiator (very small) and then attach a clamp and the temp sensor to it, rather than trying to wedge the fairly large temp tube into the radiator itself like Flex-A-Lite suggests (would not work for me). My radiator though has the back side closed to enhance air pulling effect, so mounting the sensor in front isn't ideal it seems. I am rather thinking though about mounting it to the top back side of the radiator where the hose connects, using thermally conducting epoxy to provide a consistent temp reading.

That looks like an oven control. Should work, though. I wonder if the previous owner ditched the mechanical fan due to clearance issues with the new rad mounting. (i.e. the new rad may sit closer to the water pump than the original)

I mounted mine on the front side and used the push-through sensor. It stays in place, works fine and is easily adjustable. I even made markings for various temperatures. There are a number of reasons to go with the electric fan. I also used a neat aluminum shroud made by Old Air Products.

I have been down this electric fan route and used the sensor that pushes through the radiator fins. I bought the adjustable one. It was a PITA. I could not get the fan to come on at a reasonable temperature both moving and stopped -- one or the other. I was trying to use electric only. My solution was to have the radiator shop solder a bung in the top tank to take a 3/8" pipe fitting. You could also drill the water outlet neck for a 3/8" fitting. That would be cheaper and just as good, I think. Then I went down to the Peterbilt truck dealer and they had a selection of fan switches both normally open and normally closed in various temperatures. I picked a temperature cutoff that was at least 10* above the thermostat temperature. If you pick too low a temperature, the fan won't shut off again while the motor is running or until you go down a hill. So if I remember correctly, the fan comes on at 205* and off at 195* and I can run a 180* t'stat, or something lower, like a 160.

My SPAL pusher fan draws a lot of current so it's powered through a 50A relay wired directly to the battery (with circuit breaker, of course). The ignition switch will not handle that much current. I can tell when the fan comes on because the ammeter swings over to 30A charge and goes back to ~0 when the fan shuts off. Set up this way, it'll come on a couple minutes after you've shut the engine off at a rest area, for example, and stop you from boiling coolant out on the parking lot. There is a thermosiphon action in the cooling system so the coolant will circulate even with the water pump not running.

This is used in conjunction with an 18" six-blade mechanical fan. In hot weather, pulling a hill, loaded, I can watch the temperature gauge climb to about 205 when the electric fan comes on and then stop climbing. Neither mechanical nor electric provides adequate cooling alone. I really would like to use the electric alone for noise reduction but it just isn't adequate on a long pull, say, more than 2 or 3 minutes. There isn't room for a clutching fan in an AD chassis with the 56 and later water pump. At least not in any combination I've found. If anybody knows of one please let me know.

Electric fans might be a good "belt and suspenders" approach to assist a mechanical fan, but there's no substitute for a fan with 100 horsepower or so driving it. My father's B-17 didn't have four 1200 HP electric motors driving the propellers. They used big gasoline engines and 3 blade propellers 12 feet in diameter for a good reason. By the time you consume enough electric power to do much good keeping an engine cool, fan noise is going to be a problem- - - -no way to avoid it. I'd suggest trashing the "puller" fan and going back to an engine driven one, and maybe adding an auxiliary pusher for traffic and/or air conditioner assistance only when necessary. If coolant isn't boiling out past a pressure cap, the engine isn't "overheating" no matter what the temp gauge indicates.
Jerry

Some thoughts...

Some cars don't have the fan wired to the ignition. You hear the fans still running after the driver has locked the car and walked away. Don't remember which cars. My hybrid does things while parked in the garage - a bit disconcerting at first - did I leave something on?

The stock 1950's generator may not be able to keep up with an electric fan while at idle. While at idle, with my heater fan going, my truck would stall as the voltage dropped and the ignition cut out. (I solved the problem by installing a 12V to 6V converter for the heater fan). So, I suspect than an alternator may be in order if you use an electric fan.

So just feedback to the thread. I installed a thermal switch (electro-mechanical thermostat) inline with the fan relay, and it works like a champ (so far).

I ended up epoxy mounting the thermal sensor right to the back of the radiator at the neck to provide a solid connection, using steel reinforced epoxy... seems to work pretty good.

Here's a picture of the final solution (although I'll probably move the switch once I get all the tweaking done.

If it works for you that’s all that matters.