Do I need to change my fan?

Slowleak · May 16, 2018

mduenas said:
I can’t wrap my head around this. With the stock radiator I would reach 220-234 if I was in traffic for hours. With my Ron Davis, I hit 238 in 10 minutes. The moment I get to 15 mph for 30 seconds or so the temp drops so fast to 209 or lower. It is 70 degrees out today. Is it just from my 5 blade fan? Things do seem worse wth this radiator. But then if I switch back, I’m out $600+

Edit, well the temp just sky rocketed to 250 and I’m boiling out my cap now.

I think you are fighting issues with both the shroud and the fan.

The fan you have is the wimpiest of all the V8 Bronco fans. I would definitely replace it before changing anything else.

I noticed in your pictures that there is a large gap between the shroud and the edge of the radiator, at least on one side. I would close any gaps off so the fan doesn’t pull hot air from under the hood thru the shroud, bypassing the radiator. All those gaps can reduce the amount of air actually pulled thru the radiator.

At idle, you could also have hot air recirculating back under the grill and getting pulled back thru the radiator. A bigger fan moving more air will help with that.

If you stick a sheet of paper up to the grill at idle, the airflow should hold it there. If not, you have an airflow issue, not a radiator issue.

Slowleak · May 16, 2018

jw0747 said:
My preference is a solid blade fan like this. Pulls more air at slower speeds and I've never had an overheat problem. Runs at 190-195 degrees all day.

https://www.summitracing.com/parts/der-17317

I tested that Derale fan with an anemometer against my grill. At idle it was pulling about 500cfm. A little better than my old stock 6 blade.

The 18 inch 7 blade flex fan was pulling 760cfm at idle. Much better than any fan I tried. I spent a week swapping and testing fans. I think I was just bored silly.....

blubuckaroo · May 16, 2018

Hayden makes a fan that's as close as possible to the famous Bronco supercooling fan. I had to replace my original last year after mine was destroyed in a performance demonstration.%)
https://www.summitracing.com/parts/hda-3718
Hayden has some sort of horsepower or displacement disclaimer in the Summit catalog, but neither Summit or Hayden know how or why it got there.
This fan works great! And for $50, it's a bargain.

mduenas · May 16, 2018

Slowleak said:
I think you are fighting issues with both the shroud and the fan.

The fan you have is the wimpiest of all the V8 Bronco fans. I would definitely replace it before changing anything else.

I noticed in your pictures that there is a large gap between the shroud and the edge of the radiator, at least on one side. I would close any gaps off so the fan doesn’t pull hot air from under the hood thru the shroud, bypassing the radiator. All those gaps can reduce the amount of air actually pulled thru the radiator.

At idle, you could also have hot air recirculating back under the grill and getting pulled back thru the radiator. A bigger fan moving more air will help with that.

If you stick a sheet of paper up to the grill at idle, the airflow should hold it there. If not, you have an airflow issue, not a radiator issue.

I pult aluminum tape around the shroud and closed all gaps, that’s what you are seeing. New shroud is on the way. A piece of paper does stick to the grill when I file. But now I wonder if I have a stuck thermostat and the cap I just bought from wild horses is probably bad. Just got home finally, and watched coolant seeping out of it, and engine was 209, can’t keep it cool. West coast bro cos had my Truck for a year working on it, I worked on it for a year prior. Unfortunately if I can’t solve this issue I’ll be selling it :/

Slowleak · May 16, 2018

mduenas said:
I pult aluminum tape around the shroud and closed all gaps, that’s what you are seeing. New shroud is on the way. A piece of paper does stick to the grill when I file. But now I wonder if I have a stuck thermostat and the cap I just bought from wild horses is probably bad. Just got home finally, and watched coolant seeping out of it, and engine was 209, can’t keep it cool. West coast bro cos had my Truck for a year working on it, I worked on it for a year prior. Unfortunately if I can’t solve this issue I’ll be selling it :/

Ouch....Sounds like you are having some sort of “event”. The gap I was seeing is in the picture below looking down the side of the radiator below the upper hose.

Don’t sell it! Just keep after it... try a new thermostat, fan, and the new shroud.

mduenas · May 16, 2018

Slowleak said:
Ouch....Sounds like you are having some sort of “event”. The gap I was seeing is in the picture below looking down the side of the radiator below the upper hose.

Don’t sell it! Just keep after it... try a new thermostat, fan, and the new shroud.

It is an event that’s testing my patience. Ha happen to my last bronco too!
He gap between the radiator and shroud is because I have to have the shroud off to the side to fit my fan. The shroud doesn’t cover 100% of my radiator. Not sure what to do about that.

Just got home and opened my wild horses steel radiator shroud, it as well, is not as wide as the radiator, so I will still have that gap.

Justafordguy · May 17, 2018

blubuckaroo said:
Hayden makes a fan that's as close as possible to the famous Bronco supercooling fan. I had to replace my original last year after mine was destroyed in a performance demonstration.%)
https://www.summitracing.com/parts/hda-3718
Hayden has some sort of horsepower or displacement disclaimer in the Summit catalog, but neither Summit or Hayden know how or why it got there.
This fan works great! And for $50, it's a bargain.

X2, I tried several different flex, electric, and rigid fans before I found this same Hayden. It's the only fan that keeps mine cool here in the Florida heat. Now I can idle for hours on the trail and never even get close to overheating, and I do have A/C.

Rustytruck · May 17, 2018

You have 2 things happening at Idle slower fan so less air flow. Slower water pump speed so less water flow. What diameter is your water pump pulley. Smaller diameter moves more coolant at lower speeds. I also recommend the Robert Shaw performance thermostats they are far better than anything out there. Make sure that openings between the radiator and core support are closed off. You don't want hot air going around the radiator in the engine compartment being sucked around and entering the radiator again. Also check along the sides of the engine and the fender wells and clear those areas as best as you can. Air can't move through the engine compartment if every thing is blocked and keeping hot air from getting out. Particularly bad on passengers side with the heater hoses and in your case air conditioner lines.

https://www.summitracing.com/search...obertshaw-series-high-performance-thermostats

mduenas · May 17, 2018

Rustytruck said:
You have 2 things happening at Idle slower fan so less air flow. Slower water pump speed so less water flow. What diameter is your water pump pulley. Smaller diameter moves more coolant at lower speeds. I also recommend the Robert Shaw performance thermostats they are far better than anything out there. Make sure that openings between the radiator and core support are closed off. You don't want hot air going around the radiator in the engine compartment being sucked around and entering the radiator again. Also check along the sides of the engine and the fender wells and clear those areas as best as you can. Air can't move through the engine compartment if every thing is blocked and keeping hot air from getting out. Particularly bad on passengers side with the heater hoses and in your case air conditioner lines.

https://www.summitracing.com/search...obertshaw-series-high-performance-thermostats

My pulley is 5.5 diameter. Should I go to a 4.5?

Also will this 180 thermostat be a good one? https://www.summitracing.com/parts/bra-330-180

Or should I go to a 160?

As far as closing off radiator and core support, should I apply aluminum tape between my ac condenser and radiator? And along the sides of both, to seal it off completely? Also, the shroud does not cover the radiator 100%, it leaves about 1inch or slightly more open on the side of the core, being a Ron Davis I’m assuming it is slightly larger than stock, what should I be doing about that gap?

B RON CO · May 17, 2018

Hi, you could also add a bottle of Water Wetter. It seems to help lower the water temperature.
We use it in our Saturday night stock car. Good luck

gr8scott · May 17, 2018

Keep plugging at it, you'll get it good sooner or later. I've been running the same radiator since 2011 and never once
overheated. As you can see, my steel shroud doesn't cover my entire radiator either, but its never been a problem.
I do run a 18" fan, though.

mduenas · May 17, 2018

B RON CO said:
Hi, you could also add a bottle of Water Wetter. It seems to help lower the water temperature.
We use it in our Saturday night stock car. Good luck

I did add that. I have also only 20% coolant to water ratio, so water wetter should be more efficient

Rustytruck · May 17, 2018

mduenas said:
My pulley is 5.5 diameter. Should I go to a 4.5?

Also will this 180 thermostat be a good one? https://www.summitracing.com/parts/bra-330-180

Or should I go to a 160?

As far as closing off radiator and core support, should I apply aluminum tape between my ac condenser and radiator? And along the sides of both, to seal it off completely? Also, the shroud does not cover the radiator 100%, it leaves about 1inch or slightly more open on the side of the core, being a Ron Davis I’m assuming it is slightly larger than stock, what should I be doing about that gap?

The purpose of going to the high performance thermostat is for the quality of the opening and the time that it is truly open. The performance thermostat will be open at 180 with a bigger opening than a stock thermostat that may only start opening at 180. You don't want to go below 180 degrees or you can get cylinder taper wear. If you had fuel injection you need a 190-195 thermostat so your fuel system doesn't get stuck in a closed loop situation.

As for changing the pulley that is a great expense and requires all new belts that would be the last thing I would change. Is your current pulley much smaller than the crank pulley.
Right now getting a properly working fan capable of pulling the air you need is most important. You know your radiator is good as it keeps the engine cool when you ask it to make power.

jhill52 · May 17, 2018

It looks to me like the shroud opening is much larger than the fan and does not come out from the radiator enough. Usually there is only a 1/2 in gap between the shroud and the O. D. of the fan.

mduenas · May 17, 2018

Rustytruck said:
The purpose of going to the high performance thermostat is for the quality of the opening and the time that it is truly open. The performance thermostat will be open at 180 with a bigger opening than a stock thermostat that may only start opening at 180. You don't want to go below 180 degrees or you can get cylinder taper wear. If you had fuel injection you need a 190-195 thermostat so your fuel system doesn't get stuck in a closed loop situation.

As for changing the pulley that is a great expense and requires all new belts that would be the last thing I would change. Is your current pulley much smaller than the crank pulley.
Right now getting a properly working fan capable of pulling the air you need is most important. You know your radiator is good as it keeps the engine cool when you ask it to make power.

I have fitech. o I should be at the 190-195 correct? I just want to make sure I do this right, so I don’t have to do this again. My water pump pulley is 1/2 inch smaller than crankshaft pulley

mduenas · May 17, 2018

I’m also very Concerned since it skyrocketed to 250 before I could pull off the freeway that I damaged my motor. Or blew a head gasket. I don’t see any oil coming out, or white smoke in my exhaust. Sounds a little louder I believe, unless I’m perinoid and just hear more water running through the radiator

charlie6976 · May 18, 2018

mduenas said:
It is an event that’s testing my patience. Ha happen to my last bronco too!
He gap between the radiator and shroud is because I have to have the shroud off to the side to fit my fan. The shroud doesn’t cover 100% of my radiator. Not sure what to do about that.

Just got home and opened my wild horses steel radiator shroud, it as well, is not as wide as the radiator, so I will still have that gap.

I think I had a similar fan shroud interference. I trimmed the composite shroud on the right (passenger) side where the fan hit. Stock composite then fit radiator properly.
And like was stated, find out what temperature your engine should run at and get the correct thermostat. The thermostat doesn't cool the engine, it's just to maintain a minimum temperature (who knew). The rest of the cooling system keeps (or tries) the temperature in check.
I have the 7 blade fan on a 351c with a/c.

mduenas · May 18, 2018

charlie6976 said:
I think I had a similar fan shroud interference. I trimmed the composite shroud on the right (passenger) side where the fan hit. Stock composite then fit radiator properly.
And like was stated, find out what temperature your engine should run at and get the correct thermostat. The thermostat doesn't cool the engine, it's just to maintain a minimum temperature (who knew). The rest of the cooling system keeps (or tries) the temperature in check.
I have the 7 blade fan on a 351c with a/c.

Did all your cooling issues go away with the 7 blade fan? Mine arrives today and I hope it fits in the steel shroud

charlie6976 · May 19, 2018

mduenas said:
Did all your cooling issues go away with the 7 blade fan? Mine arrives today and I hope it fits in the steel shroud

I kept the 7 blade fan from the 302 I took out. The ford 7 blade seems to pull the most cfm. I have a 195* thermostat because that's where the 351c needs to be. So far, I have not created an over heating problem.

Eoth · May 19, 2018

Your engine bay looks great. How new is everything? Have you alway had this cooling issue? Is it possible your water pump rotation is incorrect?

Do I need to change my fan?

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