New build overheating

[jstek]

Did you take a temperature reading right at the gauge sending unit?

Well, where exactly would that be? Seriously over my head here.

 

[cldonley]

The brass colored item is the sending unit. Or should be.

 

[gnpenning]

First, you did a awesome job with your pictures.

I know Paul will do a great job answering on where to check temp so I'll try to be brief. Where the upper radiator hose is attached to the intake manifold you want to check there and compare to what your gauge is saying. Hit a few other spots with the IR gun when hot.

If you know what header tubes are hit each one of them with the IR gun as well. As close to the head as you can reasonably do. You are checking for any big differences in temperature.

As mentioned that fan doesn't cover much of your radiator. You want to be pulling air through as much as your radiator as possible.

You have a 2 belt setup with power steering, air conditioning and the alternator being run. The alternator should be fine and not squeal when starting. My concern is how little wrap the belt has around the power steering (PS) and AC pump. Have you tried the AC yet? Any belt squeal when turning the steering wheel?

You are doing great, please ask for clarification on things you aren't sure of. Don't be surprised if someone on here that is local to you would be glad to help.

 

[Broncobowsher]

Pictures are great. This is one that I could walk past at a car show and know it has cooling issues. That half inch gap between the fan and radiator is a huge problem. If you think with the hood closed, the engine compartment is slightly pressurized by the fan pushing air into it. That open ring is a low pressure area. Air will loop around and back into the fan completely skipping the radiator. Even a little gap, a foot of ¼" gap, is 3 square inches of airflow bypassing the radiator.

If you took the back of the radiator and made a box the size of the core and maybe 2" deep. Seal the edges with foam tape and put the fan on that, you would maximize the fans performance. The box would be a plenum. It would even out the airflow from just the blades aligning with the core to the whole core. More trick would be holes around the corners with flaps so ram air can blow through and not get restricted by the fan. But you can't do this. Looking at the photos you just don't have the room to stretch the cooling system a couple inches. It's looking like a factory style shroud (still the boxed plenum idea) and a mechanical fan.

The A/C compressor looks like it might fight you some. Would it be possible to mount it on the back of the brackets instead of the front? I can only see the adjuster in the pictures, don't know the others. That might put you on the front groove of the pulley instead of the rear and gain you about ¾" of clearance without really changing much.

That loop above the A/C. If the cooling system is not 100% full, that will turn into an issue. As long as you have a good recovery tank and it is completely aired out it can work. Ideally, if you have to keep that loop, the cap on the radiator should be blanked off and a new pressure cap fitting installed at the high point. There are other ways of doing it. A degas bottle and pressurized coolant bottle is how nearly every new car does it these days. Actually fairly common even 25 years ago. There are more parts to the system. Cooling system pressures are more stable. The coolant bottle does not have to be the high point in the system.

 

[nvrstuk]

Pic shows a lot- good job.

You are pulling air when going slow thru about 40% of your radiator because you don't have a shroud directing air thru your radiator to your fan at low speed. When going appr 45mph or so ENTIRE radiator is getting lots of air thru it- like the equivalent of your fan pulling air thru the entire radiator but your pic shows that your fan is only pulling air thru a small percentage.... all this typing by me means that you REALLY need a fan shroud so you're cooling the entire radiator.

The electric fan is marginal by itself, coupled with inadequate airflow being pulled thru by the fan means inadequate cooling at low speeds but since 302's are relatively easy to cool you might be just fine with only installing a shroud.

Relatively inexpensive fix.

 

[DirtDonk]

The only issue I have with all the recommendations for swapping out the fan, is that plenty of us have had trouble cooling Broncos with mechanical fans over the years as well.
I agree they are typically better, when done right and with the right fan (except perhaps when compared to the most powerful electric fans) but they’re not always the be-all and end-all and cure for every cooling issue.
Especially, as in this case, where the worst problem is at low speed.

 

[nvrstuk]

Just to clarify tho, w/o working the engine hard, just cruising down a dirt road at low speed it overheats. Soon as they cruise down a road at 30-45mph there isn't any overheating because there is very little load on the engine. Also we were told in a later post that it would overheat just idling for 25 min or so...

that means IF they let it get up to 232 deg and then went for a drive at 30-45mph and the temp dropped which I'm sure it would that they will have confirmed that the problem is AIR flow.

IF all the parts are working-
-like timing, which usually causes problems when advanced too far at higher rpms like at 45mph but not an issue idling
-Radiator- be a problem at both speeds
- t stat, both speeds
-air pocket (almost impossible if the cooling works fine other times)
-actually not hot at 30+ mph on pavement (OP confirmed it is hot)
- water pump (usually both speeds) but it is brand new so sometimes we have to look elsewhere for problems but come back later
- rotation of wp, not an issue
-radiator blockage, not an issue
-fan rotation, confrimed correct
- coolant full
- fan on high for 2 spd setting
-gearing, not a cause

302's are easy to cool when everything is done properly. Compare 200hp cooling issues to the SAME setup trying to cool 600hp. HP = Heat

Think I addressed/posted most of the issues discussed so far.

Somehow I missed the post that had like 10 pics attached. To make the electric fan even less efficient it is spaced AWAY from the radiator. Remember, air moves in the path of least resistance so a lot of the air it is pulling is coming from between the fan mounting shroud and the radiator. Then calculate in that the fan is covering such a low percentage of the total radiator surface area.

Rad core is 361 sq in
Fan covers appr 226 sq in

The radiator only has the fan PULLING AIR thru appr 60% of it's surface area. So essentially when sitting your radiator (in a very simplistic explanation) is only using appr 60% of it's effective cooling area since there isn't any air flowing thru the other 40%.

Hope this helps in understanding how inefficient the little electric fan is WITHOUT a shroud.

 

[jstek]

OK, that is all super helpful. Seems like I might as well try a shroud before switching to a different fan. Try the simplest, cheapest thing first. Is there any reason to not just use the Wild Horses one like this: https://www.wildhorses4x4.com/product/Full_Circle_Aluminum_Radiator_Shroud/Bronco_Cooling_Fans
or this
https://www.wildhorses4x4.com/product/17954/Bronco_Cooling_Fans? Maybe I need to call them to verify which fits this fan....
Someone also posted about an ebay option that fits with some modification, but one of these might be already the right fit?

 

[jstek]

Also, I am located in Santa Fe, NM. If anyone HAPPENS to know a mechanic in the area that works on these kind of projects, please let me know! I really don't want to drive it an hour on the crazy busy highway to the mechanic I trust most. I need to find someone closer, because I'm sure this won't be the last time I need help

 

[nvrstuk]

So long as you can mount the fan securely to the WH shroud and not allow any air gaps where the fan connects to the shroud you should be good. I mean, we use weatherstripping to seal the shroud to the radiator to limit air flow leakage but just looking quickly at that shroud I don't see a quick and easy way to mount the fan to it.

I will go back and look at pics but if you have the OE timing/dress you can just bolt on a new WP pulley, mount the 7 blade fan on it, put the shroud that linked on and be done- unless I'm missing some other mod that won't allow you to do that.

Gotta get to work, out of coffee and I lot's of wires (like over 60) to connect for my DD.

Ask the WH guys how to seal their fan to a stock EB radiator with some kind of shroud? They should have something that would do this I would think.

Paul??

 

[ba123]

OK, that is all super helpful. Seems like I might as well try a shroud before switching to a different fan. Try the simplest, cheapest thing first. Is there any reason to not just use the Wild Horses one like this: https://www.wildhorses4x4.com/product/Full_Circle_Aluminum_Radiator_Shroud/Bronco_Cooling_Fans
or this
https://www.wildhorses4x4.com/product/17954/Bronco_Cooling_Fans? Maybe I need to call them to verify which fits this fan....
Someone also posted about an ebay option that fits with some modification, but one of these might be already the right fit?

That shroud is for a stock mechanical fan, that's the problem and why I linked to the other fan like yours they sell but with the right shroud and then a link to one that would work but would take some modification.

Any idea where the fan was purchased from? If it was from WH, since they do sell that one, maybe they'd make an exchange or be able to get you the different shroud...not sure but at least worth a try.

In all honestly, it's hard to tell how much room you have and it would stink to buy a shroud that pushes your fan out too far and hit the water pump and not be able to use it, so be careful in your choice. The ebay one I posted is only 1/2" and the reason it worked for me and I had little choice since I didn't have room.

You might have enough room for a mechanical fan and that WH full circle shroud though and then not have to worry about anything.

Is if possible for you to measure from the edge of your water pump pulley to the surface of your radiator?

This:

 

[Timmy390]

Sure looks like a gap between the fan and radiator. The electric fan should be up against the radiator. The mounting hardware that came with the fan will mount it that way. Mine is against the radiator using the mounting hardware.

Tim

 

[ba123]

Sure looks like a gap between the fan and radiator. The electric fan should be up against the radiator. The mounting hardware that came with the fan will mount it that way. Mine is against the radiator using the mounting hardware.

Tim

+1 on trying that as well. It might pull paper but a fan is going to pull most from the easiest spots and if there's a gap, there is less resistance and will take more air from there and then through the radiator will pull whatever is left.

I think a shroud no matter what but either moving the fan closer or putting weatherstrip between the fan and rad to take that space up in the meantime if def something to try out. I'm 100% sure that will make a difference.

Try He shroud takes that one step further by creating no gap AND pulling from the whole surface.

 

[Wild horse 75]

One option to try closing up the gap would be to get some push on ball weatherstripping and putting it on the shroud against the rad core. That would seal it up so it has to pull through that part of the core. I do agree that the best solution would be to get a proper fan and shroud combo that covers 100% of the rad. And optimally had relief vents with rubber dams so the shroud doesn’t block airflow in motion.

 

[DirtDonk]

Looks like it’s spaced off the radiator due to some custom mounting brackets.
Fairly nicely done, and avoids the sometimes problematic issue of mounting the fan through the fins.

Heck, at this point, rather than buying some kind of a shroud, you could create your own temporary shroud, using heavy paper, light, cardboard, or plastic. Something that semi flexible and trimmable, that you could, clamp, or tape, or glue to the radiator, and then form around your fan duct.
This would be a quick and easy test of the theory of pulling enough air through the radiator. Or if the fan is powerful enough.

 

[bmc69]

I guess I'm just lucky.....I run that fan with no overheating issues.

That fan is a two speed fan.....I would verify it's wired correctly with controller. It should have two settings i.e. temps. One for low speed and one for high. When mine kicks on high speed while sitting in traffic I can see the temps start to drop. My ECM controls my fan.

X whatever on the IR heat laser gun. I have one and use it all the time.

Tim

I've given up on any electric fan that throws less than 4000 CFM...

OP's setup would be fine with a full-area shroud, fitted with a thermo-clutched 7-blade fixed pitch fan, properly spaced in to the opening of the shroud. Done. Problems over.

 

[Broncobowsher]

For the fan shroud...
Be sure to remove the fan from the radiator and fit it into the shroud. I don't remember the diameter of the hole in the shroud, nor do I know the outside diminsions of your fan. It would take a little fabrication to install the electric fan in the shroud. There will probably be a gap around the edges that will need to be filled in. At which point you made a fan very much like most modern cars.

It sounds like the fan might actually move enough air.

I know at one time Driven Auto Parts sold a steel shroud that cost less than the aluminum Rod Davis unit. Randy is partially retired now. Still owns the business but sold the land. Does it on the side.

 

[jstek]

That shroud is for a stock mechanical fan, that's the problem and why I linked to the other fan like yours they sell but with the right shroud and then a link to one that would work but would take some modification.

Any idea where the fan was purchased from? If it was from WH, since they do sell that one, maybe they'd make an exchange or be able to get you the different shroud...not sure but at least worth a try.

In all honestly, it's hard to tell how much room you have and it would stink to buy a shroud that pushes your fan out too far and hit the water pump and not be able to use it, so be careful in your choice. The ebay one I posted is only 1/2" and the reason it worked for me and I had little choice since I didn't have room.

You might have enough room for a mechanical fan and that WH full circle shroud though and then not have to worry about anything.

Is if possible for you to measure from the edge of your water pump pulley to the surface of your radiator?

This:
View attachment 920884

Looks like 3.5"

 

[ba123]

Looks like 3.5"

Then if you do add a shroud to this, it would have to be a slim one, like 1/2".

I think your choices are:

1) weatherstrip around the fan how it is or move it closer abd see how much difference that makes and if it makes a noticeable difference, then move forward with a better shroud to get a little more.
2) go non-electric stock fan and shroud

You could of course spend more and get a different electric fan and shroud but since you know you have a problem with this one, that might not be the right move.

 

[rocknhorse76]

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.