New build overheating

[ba123]

The best cooling setup I found with stock sheetmetal is the Explorer front dress and clutch fan, a quality radiator (WH staggered 4-row with triple pass, RD aluminum, TBP 3-row aluminum, Griffin ,etc), and the RD full circle aluminum shroud. Use the metal fan for a thick core and the plastic one with a stock sized core. I cool my 408 without any issue using the Explorer fan with an essentially stock sized Griffin universal radiator and a home-built shroud.

totally agree, but nobody is gonna change all that on a new build that's complete with enough room for a fan already. No reason.

 

[nvrstuk]

I'm not sure why the OP hasn't responded to yours and my suggestions on just running even the stock 7 blade fan. Half hidden with a shroud& both could be shipped and delivered in 2 days from WH to Arizona.

OP? Why not the mechanical fan option, not even the frt dress change needed for the Exploder.

Easy, easy swap. I mentioned it several times. Just an easy fix that works for almost any 302 that doesn't have any other issues as they pull a lot of air.

 

[rocknhorse76]

I'm not sure why the OP hasn't responded to yours and my suggestions on just running even the stock 7 blade fan. Half hidden with a shroud& both could be shipped and delivered in 2 days from WH to Arizona.

OP? Why not the mechanical fan option, not even the frt dress change needed for the Exploder.

Easy, easy swap. I mentioned it several times. Just an easy fix that works for almost any 302 that doesn't have any other issues as they pull a lot of air.

Cheap and easy. If that doesn’t cut it, it’s time for the explorer setup.

 

[Geiri]

Is this the highest point?
Higher than the radiator fill cap?

 

[nvrstuk]

Is this the highest point?
Higher than the radiator fill cap?

It won't affect water flow under pressure. Like having a garden hose with the end of the hose lower than the middle. The water under pressure just pushes the air out.

 

[ba123]

It won't affect water flow under pressure. Like having a garden hose with the end of the hose lower than the middle. The water under pressure just pushes the air out.

True but it will leave air in the system since you're filling from a lower point unless it's pulling from an overflow, which I think she said it is.

 

[nvrstuk]

Correct,. Doesn't hurt flow at all but you might lose a "cup" of equiv water capacity.

I would however be concerned about the apparent hose over hose connection at the top hose to the rad???

 

[ba123]

@jstek i just thought of another question...how many lbs is your radiator cap? It should say on it.

Actually, I can see it in your pics...13 lbs is LOW. I would try a 16 lb cap and see how much it changes. I still think there are other issues, but for those modern parts, even stock style, 13 lbs is low.

I just changed mine from a 24 lb to a 16 and I might be imagining but seems slightly hotter. Although I was sitting trying to fix my very high idle for a very very long time, so might not make a difference.

The more pressure your system can hold, the higher your boiling point.

 

[Oldtimer]

I'm not sure why the OP hasn't responded to yours and my suggestions on just running even the stock 7 blade fan. Half hidden with a shroud& both could be shipped and delivered in 2 days from WH to Arizona.

She is challenged with a one hour drive to a mechanic she trusts, and he may not be happy if she shows up with box of might fix it parts.
Are there any Broncoholics in Santa Fe willing to give her some encouragement?

 

[nvrstuk]

I remember that from her earlier post.

That's why I went through all the suggestions & came up with what most now are agreeing with that it is a low speed air flow issue because of all the symptoms and "suggested" potential fixes that collected from earlier posts & I laid out on my post earlier.

I was thinking of her being an hour away when I posted that.

She's not boilng over so in my judgment being 1200 miles away diagnosing over a forum that she essentially has two choices.

1- shroud thst fits that electric fan and her radiator for a simple bolt in (WH should be able to help)

2- go mechanical after the guys at (maybe WH again) sell her a 7 blade fan & pulley and shroud that fits her radiator.

What else? She needs airflow. She has it at 35mph on pavement and cools fine. Doesn't at idle with a fan thst barely pulls air thru half her radiator.

 

[Wild horse 75]

Correct,. Doesn't hurt flow at all but you might lose a "cup" of equiv water capacity.

I would however be concerned about the apparent hose over hose connection at the top hose to the rad???

It’s a metal tube not a rubber hose. So that hose over hose you mention isn’t an issue. I don’t like the fact that it goes over the A/c compressor though. That’s going to create an air pocket that you can never get rid of. Personally if she keeps that fan with a thins shroud I would remake it and have it go in front of the compressor.

 

[rocknhorse76]

It’s a metal tube not a rubber hose. So that hose over hose you mention isn’t an issue. I don’t like the fact that it goes over the A/c compressor though. That’s going to create an air pocket that you can never get rid of. Personally if she keeps that fan with a thins shroud I would remake it and have it go in front of the compressor.

The problem with a really thin shroud is that the air basically “dead-heads” at speed. My old Taurus fan on a thin shroud cooled like a champ at idle and crawling speeds, but wouldn’t allow enough airflow through at highway speeds. I tried cutting holes and putting flaps over them but ended up going to the Explorer setup and never looked back. And that was with my old 351W. I wouldn’t even try the electric fan with my 408.

 

[Wild horse 75]

The problem with a really thin shroud is that the air basically “dead-heads” at speed. My old Taurus fan on a thin shroud cooled like a champ at idle and crawling speeds, but wouldn’t allow enough airflow through at highway speeds. I tried cutting holes and putting flaps over them but ended up going to the Explorer setup and never looked back. And that was with my old 351W. I wouldn’t even try the electric fan with my 408.

I agree. It’s a balance you have to find. If you have space a bigger shroud will always be better. But she doesn't have a lot of space as it is for that fan in there, so she can’t get a very thick shroud as it is. I’m hoping closing off the fan to the rad and changing to more water and a better cap will be enough. All that can be done very inexpensively. A custom shroud is going to be tricky if she doesn’t have someone local that can do it. And buying a shroud and electric fan combo is never cheap. I did say many posts back she may be best served getting a new shroud and engine driven fan setup.

 

[ba123]

The should I got myself and posted from ebay is 1/2" and has air flaps to allow it to flow through at speed. it works for mine.

The problem with going old school fan, is she prob has nothing for it, so will need fan, spacer, bolts, shroud and someone to do it all right. It's easier said than done, but yes, it would work.

Still though, like I said a little bit ago, I think the #1 thing to do is block the dead space on that fan to know for sure or not whether the fan is enough at all. Closing that gap should make a big enough change to notice and know it's enough. I'm somewhat guessing of course, but pretty confident that if the change isn't noticeable, that it's prob not enough for that setup.

 

[jstek]

Looks like 3.5"

Hi guys. I'm working on it. The shrouds at Wild Horses are just a smidge too deep. Won't work, even the electric fan/shroud combo is too deep. I created a temporary shroud with aluminum duct tape, and I just need time to go test drive and see if it makes a difference. Then I'll know (I think) if I can get away with some kind of custom shroud (like that 1/2" one from ebay) on the current fan vs changing everything over to a mechanical fan. I agree the mechanical fan sounds like a more sure fix, but, yes, I'm not doing this work myself so that is a much bigger endeavor. I don't anticipate ever taking this thing on the highway, so I am less concerned about airflow at high speeds. And I hear you about the radiator cap. I'll try to find one that can hold higher lbs. Once again, appreciate all the input and suggestions.

 

[blade]

I agree with those who said to close up the gap between the shroud and the radiator and see what that does. I had the same problem on my mustang with it overheating at idle. I had a gap between the fan and the shroud, closed that up and the car cooled fine.

I'm also in Santa Fe, I could probably give you a hand with things or advice, I may even have some of the parts you need if you decide you want to switch to a mechanical fan.

 

[jstek]

OK, not so great update. I did an idle test today with the temporary shroud (aluminum duct tape) and a 16 lb radiator cap. It got to 233 after 17 minutes. I didn't quite understand what everyone was saying about the gap between the fan and the radiator. I see now that the mounting kit that came with the fan was not used. That kit does mount the fan up against the radiator. I could see if I can get my hands on another bolt kit like that. Question, if the fan is mounted right against the radiator, does the shroud then just go around the fan and cover the radiator that the fan doesn't cover?? So that thin 1/2" shroud from ebay could work if I could get the 16" hole for the fan cut to 17"?
I am realizing that the air conditioning is a potential problem. The condenser sits close (3" maybe) from the radiator, which limits what fan/shroud combos work in there, including mechanic fans.
This shroud: https://www.wildhorses4x4.com/product/Full_Circle_Aluminum_Radiator_Shroud/Bronco_Cooling_Fans
with this fan: https://www.wildhorses4x4.com/product/Steel_Blade_Fan_Standard_Rotation_18in/Bronco_Cooling_Fans
would maybe barely fit. So, maybe I need to get rid of the air conditioning to go to a mechanical fan. I could live with that, I guess. But, again, more work for a mechanic that I don't have easy access to now. Head hurting now.

 

[ba123]

OK, not so great update. I did an idle test today with the temporary shroud (aluminum duct tape) and a 16 lb radiator cap. It got to 233 after 17 minutes. I didn't quite understand what everyone was saying about the gap between the fan and the radiator. I see now that the mounting kit that came with the fan was not used. That kit does mount the fan up against the radiator. I could see if I can get my hands on another bolt kit like that. Question, if the fan is mounted right against the radiator, does the shroud then just go around the fan and cover the radiator that the fan doesn't cover?? So that thin 1/2" shroud from ebay could work if I could get the 16" hole for the fan cut to 17"?
I am realizing that the air conditioning is a potential problem. The condenser sits close (3" maybe) from the radiator, which limits what fan/shroud combos work in there, including mechanic fans.
This shroud: https://www.wildhorses4x4.com/product/Full_Circle_Aluminum_Radiator_Shroud/Bronco_Cooling_Fans
with this fan: https://www.wildhorses4x4.com/product/Steel_Blade_Fan_Standard_Rotation_18in/Bronco_Cooling_Fans
would maybe barely fit. So, maybe I need to get rid of the air conditioning to go to a mechanical fan. I could live with that, I guess. But, again, more work for a mechanic that I don't have easy access to now. Head hurting now.

So, on that gap... It's not easy to pull air through a radiator. If you have a gap between your fan and your radiator, it's easier to pull air from that gap and that is where the air will mostly be pulled and you will lose a severe amount of cooling because of it. Air will come from the point of least resistance. Does that help?

As far as the shroud is concerned, no, the fan needs to be mounted to the shroud, which will allow the fan that is not as large as the radiator pull air from the entire radiator surface instead of just the 17" of the fan. Does that make sense? That's why you need a thin shroud, so that the shroud PLUS the fan fits between your radiator and the water pump pulley.

On the fan and shroud question posted, make sure you don't have a body lift. If you do, you need a shroud to match it. If only suspension lift and no body lift then it's stock sizing. That mechanical fan and shroud would DEFINITELY fit, as the fan sits on the end of the water pump, usually with a spacer to get it the right distance from your radiator and that shroud fits nicely around it. You would need that fan, shroud, most likely longer bolts as they would hold the fan AND the water pump pulley and likely a spacer.

And I don't think you need to do anything with the AC. Just don't use it until this is resolved. It doesn't hurt being on there aside from the condenser taking space but you can get through this with it on. Don't dump it!

 

[nvrstuk]

Sometimes it helps to hear it all again so it sounds like more "voices" are agreeing so, everything ba123 said.

Two reasons why the fan didn't cool with the tape mod is because like Ben said-

1- the fan needs to spaced away from the radiator and to the shroud so the ENTIRE radiator can have air flow thru it, into the shourd and have the fan PULL it out towards the engine- all with the least amount of gaps or air leakage spots as possible (like he mentioned above and I mentioned several pages back- super important.

2- the fan still is only pulling air thru the diameter of the fan NOT thru the other 40% of the radiator that is exposed and doesn't have the shroud to direct air to the fan after it comes thru the raidator.

Can I attach a pic to show a blown up view of the fan, then shroud, then {edit radiator{ and see how they are spaced? This should help as pics always help me!

 

[73azbronco]

https://www.motortrend.com/how-to/b...osition of the fan,rear opening of the shroud.