Projects Losing My Cool

I'm looking for advice or experiences. I have a '65 F100 with a mostly stock inline 300 six. Motor is fresh, as is the water pump and T-stat. It run really nice. I have an oversized three row aluminum radiator, and AC is installed on the truck.
When I bought the radiator, I ordered the bare radiator, but it actually came with two 12" fans, and the only info I've been able to get from them is the power draw of 80 watts. Roughly 6.6 amps each.
I have one fan set to come on at 180, and the other set to come on at 190.
I have very little experience with electric fans. I know my RAM 1500 uses one, but also has an engine driven fan.
Driving down the road, Ol' Furd runs close to the T-stat temp of 180 to 190. But in town, with the AC on during the 100° plus days we have here (104 today), the temp climbs. Not dangerously high. Just uncomfortably high. 210°. And it does so quickly.
It doesn't seem to bother the truck. It's not puking coolant or even pushing any out into the recovery bottle.
It's obvious to me that it's not getting enough low speed airflow through the radiator. Most likely the "NoName" 12" fans are not moving enough air.

So the advice I'm looking for is should I go for two higher performing 12" fans with their corresponding higher amp draw? (I have a 100amp alternator)
Or, a big single electric fan?
Or, go back to an engine driven fan, possible with a clutch, and DEFINITELY with a shroud?

 

This would be my choice

 

I'd leave it as is. You're nowhere close to having an overheating issue

 

Set both fans to come on together and understand that in those ambient temps, running an old car with aircon added its going to see temps rise in the coolant system. The fact that its not over heating seems to indicate to me that your current setup is working.

 

Yup! Engine driven with a good shroud.

 

I’d set them both to come on at the same temperature. Running just one at a time you are only cooling a portion of the radiator, then by the time the other kicks in it’s already behind and trying to catch up.

 

Well now... you already have the two electric fans. One thing I fail to understand is why you want the cooling fans to come on as the thermostat first opens, doesn't make much sense to try to cool a motor as the motor finally reached the stat temp and the stat opens. If your fan temps are both adjustable, I would set both fans to come on in the 200-205 range. Above the stat opening range, but well short of overheating.

If you desire a change, go with the motor driven fan and shroud.

 

"Going down the road"........it should not need a fan!
That being said.......is the radiator cap in good shape?...Maybe go to a higher pressure cap?
Water wetter??? Distilled water and a dab of coolant to prevent corrosion.. should be the ideal coolant.
Headers?! Maybe wrap 'em....(maybe not!)
Sitting still and the fans on......will they hold a sheet of paper to the from of the radiator/AC condenser?
(It should!)
What about a rubber dam between the radiator support and the hood? Let air ONLY come through the radiator not leak around it.
Lottsa stuff to check but like said above......with triple digit weather it's do'in pretty good.
6sally6

 

I reckon the answer to that is to keep it close to the T-stat opening by getting a running start at it. At any rate, in city stop and go, it blows right past that anyway. After all, an engine driven fan is pulling air through when the motor is started.

Going down the road, 40+ mph, it stays at around 190, So that tells me the radiator has enough capacity, and I run the 50/50 blend of antifreeze/coolant and distilled water.
Stock iron exhaust manifolds.
Now that damming up the air over the top of the core support to the hood....
I'll look at that!

My concern is the temp getting away from me in the heat of the day in traffic. I reckon it'll just take running it in those conditions to find out. I just recall a time wifey and I got stuck in stopped traffic in 110° heat with no escape. She woulda melted if I had turned the truck off along with the AC. For 45 minutes, idling and a standstill, and my Ram 1500 never budged off 205°.
Could I count of Ol' Furd to do that?
At this point....not confident.

Thanks for your insight fellers!

 

Just a couple questions. Do the 12” fans have a shroud so between the two of them the whole radiator sees airflow? Is there a 3rd fan on the condenser? In general I’m a fan (pardon the pun) of engine fans, shrouds, and clutches. Detroit built millions of those with a/c that just worked. But if it isn’t really broken, and it doesn’t sound like it, no sense spending a bunch of time, effort and money to fix it.

 

Or, go back to an engine driven fan, possible with a clutch, and DEFINITELY with a shroud?
If you have the room a clutch fan with a shroud is simple and effective, I can’t say I’ve ever had one go bad.

 

Yep. Typical twin fan shroud. Exactly like in the photo below. Except for the hose outlet positions.
Third fan on the condenser? Is that something that is done?

 

Just for grins, you might check your thermostat for:
Temperature to fully open.... use a big pan of water and a meat or candy thermometer to confirm.
How big is the flow path when it is fully open?
I've had thermostats that were very erratic in terms of opening/full open temps, as well as those that don't provide much flow at 'full open'.

 

Are the fans pullers, and correctly wired to pull?
Hey, someone's gotta ask....

 

I would’ve thought that style of fan shroud is restricting air flow. The louvres are a token gesture.

 

My 300 6 in my 56 never gets over 190, though I have no A/C. But I also have a original 1985 clutch fan but no shroud. But for what it's worth I think that 210 degrees is OK. How about this... Do you have a small road with little traffic around your place you could simulate getting stuck in traffic creeping along with the A/C on? Then if it does overheat you would know for sure.

 

any idea what cfm those fans are pulling? Maybe look into that? I had a Spal dual on my 348. I let it overheat in a test to 205 then kicked the fans on and it brought the temp back to 180 where the sensor shut off the fans in a remarkably short time. No AC though that would have increased the time interval. Those fans provide 3186 cfm and the unit has the flexible flappers at the top to ***ist when running but open on the road.

 

You’re “heat issue” doesn’t sound like a problem to me. If its not boiling its not a problem. Judge your actual temperature with a heat gun at the radiator return connection on the block.
Yes turn both fans on at the same time.
Normally the engine temp ranges close to 100 degrees above the outside temp.

 

The 190 going down the road is due to the restricting plate shroud. I hate those things. I've got buddy's that won't drive their car anywhere because the always get hot, and all of them have that style shroud. Makes it hard for air to move through the radiator.

 

Thanks for the suggestions fellers.
Yes they are wired correctly. I knew someone would ask!
I'll remove the t-stat and check it for actual opening temp. Afterall, quality control these days ain
t what it used to be.
The louvers...Maybe punch a hole and use a hinged flap that opens at speed?
The CFM of the existing fans....
THAT is a good question. I have not been able to find definitive info on that. I've found anywhere from 1750CFM for both, which is likely, perhaps even a bit optimistic and not enough, to 1750 CFM for each. But given their wattage as stated by the sticker on the hub (80 watts) I would have to guess that the flow is at the bottom end of the scale. I've read that a six needs about 1500 to 1750 cfm. But at 300 inches, it's as big as a small V8, which would call for 2400cfm or thereabouts.
I looked at that Spal dual set up the other day. Spal seems to be a quality choice. Pricey, yes. That dual 12" deal can have up to 4000cfm, but the current draw is big as well as the price.
I reckon I'll work to optimize what I have in the immediate term. But I think I'm leaning toward a conventional fan and build a shroud.

 

Mike, those Spal twins can be had for around 290 if you shop around. 500 is just crazy money. Good idea on flaps instead of those louvers and I would invest in a heat gun and check the top of the radiator just for grins.

 

Many years ago , a friend and I were coming back from a rod run in Iowa, we had a cooling problem with his blown sbc in his 1937 Chevy all week, it was the first time with out , with a blower on . Runnin 210* we stopped in a small town of green top Missouri . At a standard station and the old timer there did some cooling work on farm equipment, we ask if he could fix it till we get home .?? He said “ yep “ $15.00 bucks . What a deal ,!!! And he did ,he double clamped all hoses and put black tape over the temp dial , and said ,, now you boys put a good shroud on that thing , and keep your damn eyes off that temp gauge … if it ain’t pukin water it ain’ to hot !!! “ nuff said “

 

Just remove the shroud and strip mount the fans, you can always reverse it later if that makes you comfortable, or is there really no problem.

 

Yup. They built the trucks to be reliable as cheaply as possible, using the technology of the time. These days just about everything new runs electric fans instead. While it may not have quite the same level of keep-it-simple-stupid-simplicity it gives a completely different level of cooling control.

 

It is hard to tell the distance between the radiatior and the fan shroud for air to duct freely through the whole rad. The rubber flaps may help as when the truck gets to run a bit then more air can go through through the rad naturally. The fan shroud looks like it may be restrictive to air flow.

 

I had a 72 ford camper special that I installed an aftermarket ac on and it never overheated. Factory V8 engine driven fan and shroud.

 

If you are stuck on running an electric fan, the 90's Ford Taurus had a two speed fan with a shroud that can be modified to fit most stock sized Ford radiators. They move a m***ive amount of air even on low speed. The Mustang and Maverick guys swear by them.

 

So driving down the freeway today with the AC on and outside temps at 104°, the temps stayed at right around 190-195. That tells me the basic cooling system is working well as long as air is moving.
As soon as I got off for the two mile trip from the offramp to my house, it was up to 205°.
That tells me the fans are just not moving enough air.
While you guys are right that 205-210° is no where near too hot, the temp creep bugs me. It may stay there in extended stop and go traffic, but my gut says it'll continue to creep up.
Since this was my first foray into relying totally on electric fans, I can't say I'm satisfied. Those that mentioned the the twin fan shroud was probably restricting flow are probably correct.
And, I looked further into what my Ram1500 uses, and it's just a mechanical fan with no auxiliary electric fans. I thought it had one since a sound is made when it gets hotter such as pulling a grade towing a trailer. Probably the clutch engaging. It's a big *** noisy fan.
I also never had trouble with my old C10 with a 383 small block towing a trailer either. Mechanical fan and shroud on that.
I had originally planned to use a mechanical fan, but since the radiator came with a pair of electric fans, I decided to use 'em.
So, back to basics. I ordered the biggest Derale six blade steel fan that could be swung without interfering with anything, which was 17". Solid mount, no clutch. It's a bit too tight for a clutch I think. The low profile Hayden unit is 2.75" long, and I have about 3.25" from the water pump pulley snout to the surface of the radiator.
I also have a bunch of .050" thick aluminum sheet on hand. So, I will use part of the twin fan shroud, the part that mounts to the radiator, and build a new shroud for the mechanical fan. Tapered back as much as will be allowed so air is pulled through the entire surface.
It'll look a bit weird, since the motor is offset to the right some, not centered on the radiator opening.
Then also build a dam to keep hot engine bay air from coming around to the front of the radiator.
My gut says that oughtta do 'er!
I appreciate all your input fellers!

 

If the engine temps are 210 in stop and go traffic, but drop to 190 on the highway, the fans are not restricting the air flow at all at highway speed. No need to be concerned about that. If the fans were blocking the air flow, the engine temps would rise higher at highway speeds.

210 is not hot. Pure unpressured water in an open kettle doesn't even boil at 210, it needs to get to 212 before it starts to boil. Adding pressure raises the boiling point of water, the cooling system on the truck is pressurized. Depending on the pressure the system is under (the lbs the cap pressure is rated at will tell you the boiling point of the system on your truck, the last aluminum radiator I bought a year ago came with a 16lbs cap) , it could raise the boiling point of water to 250+ degrees. Adding a 50/50 mix of antifreeze also raises the boiling point of the coolant.

If your cooling system is not boiling over, it is not overheating.

My truck has an aluminum radiator with an electric fan (no room for a motor driven fan). That fan is off until the motor temp reaches the turn on setting (210 on my truck). When the fan kicks on, it runs about a minute and shuts off (at 195, which happens to be my thermostat opening temp). I suspect that if you have your fans turn on temp set at 190, it likely isn't shutting off until it reaches 160, if it shuts off at all! A good thermostat might not let the motor get down to the fan shut off temp, does the cooling fan cycle on and off?

So if you want to test the reliability of your cooling system, there is no need to go driving anywhere. Pick a hot day, pull your truck up to your closed garage door, about as close as you would pull up behind a car in stop and go traffic (this will block off any air movement except what the fans will pull through the radiator). Start the truck and let it idle, turn the AC to max, and sit and watch the temp gauge. Listen for the fans to kick on, and then shut off (cycling electric fans is good). Let the truck sit and idle as long as you feel the need to feel comfortable with the function of the cooling system (burning $5 gas). This will load up the cooling system about as loaded as it can get.

As a bench mark, if the engine temp gets near 230, get out of the truck and see if the cooling system is boiling over. If its not boiling over, its not hot enough to hurt the motor. If it is boiling over shut the truck off and let it cool down.

If the truck doesn't over heat under these conditions, you have nothing to be concerned with, some part of the cooling system would need to fail to cause a problem. That can happen with anything. Gene