M37 Electric Fan?

[Rodney]

Anyone convert to a 24 Volt electric puller fan? I am looking for makes and models that work well in the M37.

Thanks

[maineSS]

Try looking for a Mustang V-6- they have a single fan that pulls a lot of air. Keep in mind that electric fans use a more open fin design radiator- they can't pull high blade pitch like mechanical fans. I used a double-fan from a Chrysler in my MonteSS 305 v8 as an experiment- worked fine (unfortunately- the whole idea was to prove it couldn't work to make a point during an Internet argument). These fans pull some very high starting amps- I measured 60 on low speed and 105 on high speed for the dual unit. You should use high quality terminals, wiring, and switches.

[Rodney]

Electric cooling fans

Anyone done this? The choices for the M37 are one large fan 16" or two 10" or 11" fans. Still looking for some feedback.

Thanks

[Frank Irons]

Rodney,

I used a 16" Spal pusher fan on my M37 initially. I still am using it but have added an engine driven fan. The electric fan kicks in too late and never catches up to the temperature rise. I didn't have enough room for the engine fan but figured out a way to move the radiator forward 1.5 inches and was able to use an engine driven fan.

Frank

[Rodney]

Radiator Relocation

Thank You Frank,

Interesting, I was looking at the Spal 16". If I remember correctly, you are running a 360 Crate engine. What type of sensor did you use, block or radiator?

I'm also interested in your relocation, any photos?

R

[maineSS]

I experimented with a dual fan Concorde unit on my Monte's 305 V8. The stock unit was an engine driven clutch fan, which was quite effective at cooling. Their principal downfall is not lasting very long at engine RPM's over 4000.

I found the Concorde unit to work fairly well, even though the radiator wasn't designed for electric fan use. The low speed fan would pull about 60 amps on startup, both fans starting together would pull about 105 amps inrush current, so you'd better not do a Mickey Mouse wiring job! Running amps for both was about 30, and 15 for just the low speed.

I wired the fans with an auxilary switch that allowed me to manually turn on both for hot day stuck-in-traffic situations, which was a real good thing for temps upwards of the mid 80's.

I used an adustable radiator temp sensor- these are failure prone, so I would suggest you use one of the screw-in temp switches.

I measured the amount of depression created by both the electric fan and the clutch fan, and the clutch fan & shroud was superior. I made sure to seal the electric fan to the rad well, so it had minimal leakage. You definitely want to avoid any electric fan that isn't shrouded, and can't be sealed- they don't have the power to pull a steep blade pitch, so they need all the help you can give, especially on a rad that isn't "open" like the ones used in OEM electric fan installations. Stay away from pusher fans- they lose about 15-20% over the same fan used as a puller, and placing a pusher fan in front to "help" a puller just kills rad airflow.

The top part of the rad is the area that most needs cooling in a vertical rad, so locate your fan towards the top- use the main fan in a double unit.

Your battery & charging system need to be in good shape, as does the wiring carrying the fan current. Electric fan proponents are always claiming that electrics use less engine power, which is true at higher rpm's, but they don't mention the heavy intermittent load it imposes- these currents will start fires quicker than you can imagine. Also, they don't get along well with deep water, so if extreme fording is in your future, go mechanical.

[Rodney]

Thank you for the feedback.

I am looking at twin 11" spal 24V puller fans. The good thing about the higher voltage is the amp draw is half that of the 12 volt fans. I've found a blank aluminum shroud that should fit the M37 radiator well. It measures 19" x 21 3/4" and is made by http://www.northernfactory.com/. I'll probably use the spal fancy controller that can be hooked up to two fans. It should work off the standard electric temp sender. The first fan kicks in at 50% at a temp of your choice. As the engine heats up, fan #1 increases in speed until the engine reaches the high temperature setting. At this setting fan #1 operates at 100% and fan #2 is turned on (100%).

[maineSS]

You may want to ask Spal about the suitability of your radiator before laying down a big chunk of change- things like thickness and fin count per inch. Electric fan rads are much more open than mechanical fan rads, but you may end up just trying it. The stock M-37 engine won't develop as much heat as a V8 repower, so you probably won't have any trouble.

[Rodney]

Specs

Thanks, I was wondering about specifications for the stock radiator in terms of fan size. I know the radiators are oversized as is common in military applications. I am running a Hercules diesel. Never had an overheating problem with the engine fan (17"). The twin 11" fans I was looking at pull 30-40% more CFM's than a single 16" spal fan. They have a good tech line, I will call and see if I can get a little more scientific.

In a factory application, the Series II Hercs often relied on an electric fan.

[maineSS]

Diesels are more efficient than gas, so they reject less heat. However, you're making more HP, so you'll have to do some estimating how much more heat you need to dump into the cooling system. If you're using a non-pressurized system, you have less margin for error. I'd get a temp guage with numbers on it- "Cold" and "Hot" likely won't cut it here. Most of the diesel repowers seem to end up with an aluminum radiator.

[W_A_Watson_II]

I used a Fles-a-lite 180 Black Magic Extreme http://www.flex-a-lite.com/auto/html...c_x-treme.html

A 12volt fan with shroud that fit's the M's almost perfect and moves 3,300 CFM.

[maineSS]

One thing to remember is that fan ratings are typically "free air"- what it will pull in the open, NOT behind a radiator. The core thickness and fin/inch count have a huge effect on how much air the fan can really move when it counts- like pulling a trailer across Death Valley in August. Again, check with the manufacturer about your intended use- don't be surprised if they tell you to get a $300 aluminum electric fan rad. My Monte has the stock 305 engine/rad, and without my manual overide switch, I'd overheat in stop and go traffic on days in the high 80's.

[Rodney]

Hey Watson

What engine are you using? I just noticed the relocated bottom hose fitting in your photo. Are you getting plenty of cooling with your setup?

[W_A_Watson_II]

Rodney,

At High RPM's I have a problem, and have gone to a pressurized Cap, sped the Water Pump back up to stock speed, but still have the issue.

Some speculate it's the inability to get enough air out of the engine compartment, and the next time it's hot out and I will be running high RPM's I will run with out the side curtains to test that theory.

I'm thinking that since the radiator and engine set for almost 2 years before they say radiator fluid, that I may have some plugged tubes.

I had the lower relocated because of the 68 short snout (water pump thta has a driver side inlet.

[maineSS]

The quickest way to checked for blocked tubes is with an infrared thermometer after the coolant is circulating. Removing the side panels may not make any difference- T-bucket type hot rods typically have this problem with V-8 repowers. If the mechanical fan solves this problem, you may have found the limits of the electric fan being used with the OEM radiator. If you want to keep the electric, you'll have to get a rad designed for it. If overheating continues at road speeds over 30 mph, the fan isn't the problem.