M37 Electric Fan?

[Rodney]

Dual Fan Setup.

This is what I've come up with. I fabricated a 1" deep shroud from .056" mild steel and fitted two Spal 11", 24 volt, 70 Series fans. I am using the spal PWM electronic controler that senses temp changes from most factory and aftermarket gauge sensors. It is user programed to start one fan @50% at a low temp. Fan #1 will gradually speed up as temp rises to a high temperature setting that is also user selected. At this point, fan 1 will operate at 100% and fan #2 will start and run @ 100%.

In static tests, the fans effectively pulled engine temp down from approx 195 F to <180. Will let you know if it works on the road.

[mannyc]

if you cant cool it with a stock radiator -

you have a problem. i converted a m37 to a 360 hipo motor. used a helitool kit and orig planned an electric fan. kept at it and used a flex fan that fit. no problem cooling the truck and the stock rad was just cleaned & tested. no shroud, no pressure cap added. the stock radiator should have enough area to cool even will's v8. will, you should abandon the electric fan and go back to a metal spinner. you dont have enough projects anyway. electrics are good backups but usually they mask a problem. trucks and cars using electrics from the factory were designed from the ground up that way.

you might have an engine problem. lean runners generate heat.

[Rodney]

Electric Fan Evaluation

Here to report that the Electric fan setup does not work on my M37.

It works great for general driving, idling, crusing 55-60mph. But when I get out on the Highway and cruse 70+ MPH both fans have to come on and the temp rises to 210+ and stays there. When I come to a stop, the fans pull the temp right down, but can not handle the high speed operation. It is particularly noticable in warmer weather. Less so below 35 degrees F.

I did not have this problem with the Herc's 5 blade mechanical fan.

My question: Does anyone have any experience with replacing the factory radiator with a custom one designed for advanced cooling with an electric fan system. I see Charles offers a custom aluminum radiator. If there is significant evidence that this route would work, I would like to hear about it.

R

[W_A_Watson_II]

Rodney,

How many CFM are your fans supposed to move? The F180 Black Magic Extreme I have is supposed to more 3300 CFM.

My problems is at high RPM's even at high speeds, so I don't think I have an air flow problem. I still need to pull the radiator this winter and have it re-cleaned.

[maineSS]

Cooling problems can be tricky, and you can spend a lot of time and money if you just throw parts at them. A systematic diagnosis is time consuming, but will save money in the end. Your fan doesn't do much over 30-35 mph, it's airflow through the rad at that point. Electric fans windmill, and can obstruct flow enough so that some manufacturers have flaps in the shroud to relieve pressure. If you suspect rad blockage, an infrared temp gun can pinpoint cool vs hot areas quickly, it's a very handy tool to own. Another thing to check is head gasket leaks into the coolant that only open up when the engine is working, these will heat things up quick- and they'll get worse in time.

[Frank Irons]

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

Sorry for the delayed response but here is a photo of my installation. I moved the radiator forward to accomodate the engine fan. I retained the Spal pusher just because it had already been installed. Had the truck on the road for the first time this year and cooling seems to be fine. Had to add a coolant recovery system as the system wanted to puke out coolant after shutdown.

Frank

[Frank Irons]

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

Using a block sensor and here is a photo of the pusher fan.

[Rodney]

E Fans

My fans together pull 2580 cfm, they are 11" Spal BP70 series HD fans. I used 2 b/c they draw more cfm than the spal single 16" and they cover more of the radiator. When both are running, I can put a business card anywhere on the front of the radiator and it will stay sucked in place.

Seems we both have problems at high RPM's (and high speed). I thought about removing my custom shroud, which does have flaps installed, and making a skeletonized one that moves the fans close to the rad surface, with no shroud material blocking the back of the rad elsewhere. Any thoughts on that?

My radiator is not blocked. Seems that there is not enough airflow at high speeds. Not sure if it is my shroud, the radiator design, or some other sort of problem. Remember, the cooling system works with the factory shroud and stiff 5 blade fan that came with the Hercules kit. So that's the simple solution. Not sure if I am smart enought to chose the simple fix first...

[W_A_Watson_II]

Rodney,

We are both moving good CFM's and have shrouds so air flow should not be an issue. Mine is High RPM's regardless of speed though. Once it's hot, all I have to do is let it idle for a little while and the temp comes down just fine.

Some have suggested to me that I may not have enough room in the engine compartment to get the air out that the fan moves. I'm still thinking that with the rebuilt engine and re-cored radiator setting dry for many months while we moved that some scale/etc... has clogged the radiator. It's either that or when the radiator shop re-cored it, they did something wrong.

Will

[MasterYota]

Having driven several V8 repowered rigs of various makes, and varying engine compartment sizes has given me some insight into the cooling problems being discussed here.

Rodney - I'm going to suggest that the fan shroud you've build to mount your fans on is too shallow. Judging from the pictures it looks like its about 1/2 - 3/4" deep. If thats the case, this lack of depth is localizing the air being pulled through the rad to basically just infront of the fan. A deeper shroud would allow the fans to generate a greater draw of air over a larger surface area more efficiently. I tried a similar setup about 10 years ago, and had similar results as you. My V8 would overheat at any sustained point over 2800rpm. Slow speed was fine, but highway driving sent it into the red zone quickly. I sold the truck before I could solve the problem. But my experiences since have led to belive that was the problem. The shroud effectively blocks air flow at higher speeds.

Coolant additives work - I've ran "Water-wetter" in all my rigs for years, and have a consistently lower operating temperature, sometimes as much as 20 degrees. I also ran a hood scoop on other rigs, and that extra ventilation did help. I know that M37's would look funny with a scoop, and I'm not recommending one, but removal of the side curtains would probably accomplish the same thing. The side curtains could also be louvered (like most hotrods) to assist with hot air removal. Engine oil coolers also help, its good for the oil, and any drop in temperature can't hurt. Heat wrap on headers works well to direct heat out further down the exhaust system and keep the underhood temps down. Finally - straight bladed fans (like the one in Franks picture) tend to move a greater amount of air. The "s" shapped fans are quieter, but less efficient at moving the air.

Frank - can you post some additional pictures of how you moved your rad forward? I would like to do the same in my Cdn. M37 as I'm swapping in my BBF right now. The additional room would be a bonus. I know I've already got a little more room than the US trucks as I had the longer 251 under the hood, but any more space would be great. Was it as simple a job as just re-drilling the mount with new holes for hanging the rad on? Did you have any hood clearance issues?

Hope this helps...

[maineSS]

You definitely want the shroud, and it should be deeper, and ideally slope towards the fan, even though that's difficult fabrication. Your current problem doesn't sound fan-related, though. It sounds like insufficient coolant flow at high rpms, insufficient heat transfer from the rad to the air, or insufficient airflow thru the rad at highway speed- assuming the rad has enough capacity to do the job. One of the problems of large engines in small engine compartments is building up a high-pressure hot air zone large enough to send air around the rad, rather than thru it. The classic test for localizing fan vs other problems is running the vehicle in neutral at highway rpms with a large fan blowing at the rad, if overheating is still present, it's "other" problems.

[Frank Irons]

Having driven several V8 repowered rigs of various makes, and varying engine compartment sizes has given me some insight into the cooling problems being discussed here.


Frank - can you post some additional pictures of how you moved your rad forward? I would like to do the same in my Cdn. M37 as I'm swapping in my BBF right now. The additional room would be a bonus. I know I've already got a little more room than the US trucks as I had the longer 251 under the hood, but any more space would be great. Was it as simple a job as just re-drilling the mount with new holes for hanging the rad on? Did you have any hood clearance issues?

Hope this helps...

MasterYota,

The first photo I posted above shows what I did to move the radiator forward. Instead of mounting on the face of the U shaped support (empty mtg. holes visable) I moved the mounts inside the channel. 2 pieces of .5 aluminum were mounted in the channel and threaded for the radiator mounting bolts. The filler cap had to be relocated as pictured to clear the hood. The hood has to be clearanced on the underside to clear the top of the radiator and the hood safety catch is eliminated. I use the 2 side latches for the hood hold down. I gained 1.75" with this modification.

Frank

[W_A_Watson_II]

Master Yoda,

I accomplished mine by leaving the radiator mounts and top tanks as it, and having the new core mounted in the forward portion of the tank. As stock, the top tank overhangs the core forward say about 1.5", so I had the core installed leaving the overhang in the rear of the top tank. This leaves the filler clearing the hood, and I can leave the upper radiator opening on in front of the radiator, helping keep the road speed air directed through the radiator and not up and over it (Could be part of Franks problem, air going up and over and around the radiator at speed).

[MasterYota]

Thanks for the info Frank, I must've missed the rad cap in the sunshine in the photo.

Will, is my understanding correct that the rad shop basically flipped the top tank around 180*, instaleld a new inlet and then re attached the mounting brackets - thus hanging the rad further forward in the mount?
Also, did you stick with a 3 core rad, or was there enough room to put a 4 row core in?

Thanks for the answer's guys

[W_A_Watson_II]

Will, is my understanding correct that the rad shop basically flipped the top tank around 180*, instaleld a new inlet and then re attached the mounting brackets - thus hanging the rad further forward in the mount?
Also, did you stick with a 3 core rad, or was there enough room to put a 4 row core in?

No flipping of the top tank, it's just as it was, but the core is mounted in the front with. Basically the portion of the Radiator below top tank, excluding the brackets is moved forward. Mounts as Stock, but with the core and lower tank further forward.

New 3-core, as others said the stock had adequate cooling. If the shop doesn't find any blocking when I pull it and take it in, I might have to upgrade to a 4 core.