Cooling Solutions

[sierrablue]

For those who may be interested, this is what I did for my radiator. I've just been seeing a fair bit as far as cooling goes, so I thought I'd share what's been working for me.

I have the B350, and did not want to spend $700+ on an aluminum bolt-in radiator that still had to have mounting holes drilled in it. Additionally, it being a Jeep, I figured it would have to deal with some twisting and such, so I decided that a clamp-in style radiator would be a better setup than the bolt-in.

With that in mind I found a SBC radiator (same plumbing as a B350, AMC is unfortunately opposite) at Summit for ~$250 (if anybody's interested I can list all the part numbers for what I used), as well as some clamps and rubber insulators there. I welded two of the clamps in on the piece of sheet metal just behind the valence (it's spot welded to the bottom of the valence actually if you look), where no one will ever see them from the front. Set the radiator down in there and then I built a bracket for the top, using the two other clamps, and also utilizing the factory upper radiator mounting bolts.

Then that made it easy to install a Taurus electric fan, as well as a temp switch (also from Summit).

You'll probably notice that the radiator sticks up a lot past the top of the radiator support. It does not have any clearance issues with the hood, and I'm pretty sure just about the entire radiator has air blowing through it when you're moving, as it will be getting air both from the top scoop in the hood, and everything that enters the middle ~25" of the grille should be going through it.

The electric fan has been treating me incredibly well; temp gauge gets to the bottom of the green/normal zone whether it's -20°F or 100°F, and stays there no matter what I do. The only way I've gotten it to creep higher is if I shut it off for 5-10 minutes, and then when you fire it back up, the fan gets it back in ~45 seconds to a minute. My dad runs the same fan in his '70s Ford, and back when it had the 390, idling with the A/C blowing when it was pushing 100°, the temp hit the point where the fan kicked on, and quite literally brought the gauge all the way back to the C mark on the gauge before it shut off. We also have this fan on our 2.5 XJ, which has has electrical problems there, but it's never been the fault of the fan itself.

I also have an overflow tank, which is nice as the rad can burp itself and you don't leak any coolant.

Anyway that's what's worked for me. Stay cool everyone!

[Harry Dawg]

Nice setup.

I have the AMC 327. No fan shroud on it when I got it and I can't find a replacement. I'm thinking about going a similar direction and buying a 26" down flow radiator.
I figured I could just weld up some brackets to match the factory holes.

How does your alternator handle the added load w/ the electric fan?
I was thinking of going with dual fans, but the Taurus fan may be more system friendly.

[Yeller]

With LED headlights, Taurus fan, blower motor, and wipers all running a 64amp alternator barely keeps up, at idle probably not.

I won’t derail the thread, I’m a mechanical fan fan lol. But if your going to an electric it’s hard to beat a Taurus.

[ntsqd]

The common downfall of the GM radiator mounting design when used in fast and/or rough off-roading (think desert racing or similar) is that the top clamp flexes enough for the radiator to escape and end up in the fan. That is what my friend JEM calls a "Negative Performance Feature." My friend Ruben (you'll hear about him a lot in the future) taught me to make tabs and run some all-thread down the far side so that the radiator clamp is secured on both sides.

The pics are small enough that I can't tell if your mounts have the same Achilles Heel or not.

For fan shrouds where the OEM isn't available or doesn't fit my plan is to build one like this: https://www.jalopyjournal.com/forum/thr ... ud.380196/ The pics are gone form that thread, but if you look up building speaker panels and sub-woofer enclosures you'll find pics of how this works and just how "organic" the resulting shape can be without having to shave a bunch of wood or foam.

[sierrablue]

Sorry only just saw this. @HarryDog, I just swapped to a 12SI alternator as I kept blowing out voltage regulators on the stock one. 63 amp I think. Halogen headlights on, fan on, interior fan on, radio on it'll read right at 12V at idle, 13-13.5V the rest of the time.

[sierrablue]

The common downfall of the GM radiator mounting design when used in fast and/or rough off-roading (think desert racing or similar) is that the top clamp flexes enough for the radiator to escape and end up in the fan. That is what my friend JEM calls a "Negative Performance Feature." My friend Ruben (you'll here about him a lot in the future) taught me to make tabs and run some all-thread down the far side so that the radiator clamp is secured on both sides.

The pics are small enough that I can't tell if your mounts have the same Achilles Heel or not.

For fan shrouds where the OEM isn't available or doesn't fit my plan is to build one like this: https://www.jalopyjournal.com/forum/thr ... ud.380196/ The pics are gone form that thread, but if you look up building speaker panels and sub-woofer enclosures you'll find pics of how this works and just how "organic" the resulting shape can be without having to shave a bunch of wood or foam.

I used thin enough steel to allow it to flex around the radiator as it needs to. It was kind of an accidental perfect solution lol.

[ntsqd]

Sierra, happen to recall either the p/n or the application for the radiator? I am looking to replace the existing AL radiator with one that has a trans cooler in it and have been struggling to find a fit blindly.

[Yeller]

If Sierra is sleeping or can’t remember….. I used a very mildly modified (mildly knowing your skill set….) 67-69 Camaro radiator. Fits nicely and is available with a cooler.

[ntsqd]

Thanks! That points me in a good direction.

[sierrablue]

https://www.summitracing.com/parts/sum-381328

^I'm pretty sure this is the one--sorry.

[ntsqd]

Thanks!

[Harry Dawg]

Alright. I'm gonna beat this horse a little more.

First off, my factory radiator is a 3 row down flow with what I believe are copper cooling fins. ( too tarnished to tell). It doesn't leak, and is actually in ok shape for it's age.

Working on rodding it out just for fun, but what are the advantages to an aluminum radiator?

Besides being light weight and better flow because it is brand new. I am guessing better corrosion resistance and heat dissipation?

I think the copper core would look cool all cleaned up.

As for the fans, I get that mechanical fans are reliable, but I feel like an electric fan will cool better in some circumstances ( off-road where fan speed is slow). I was thinking about keeping my mechanical fan in the tool box as a trail spare and testing an electric fan.


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[ntsqd]

I recall reading an article written by someone with some tech credentials, wish at I could recall where & link it, but in terms of heat rejection each metal's assembly method has it's plus' and minus' and in the end it ends up being a draw.

Copper-brass is heavier, but by the time you fill them both with coolant there isn't a huge advantage to aftermarket all aluminum. OEM with plastic tanks the balance tilts wee bit more in that direction.

Aluminum can have electrolysis problems, enough so that it can kill the radiator in a pretty short time period. I've yet to see a definitive article on how, why, and what to do. I'm sure that the OEM's know, but that info has yet to filter down. Perhaps it is part of why they use injection molded plastic tanks?

Aluminum, particularly with plastic tanks, is less expensive than copper-brass and that is the real reason that the OEM's switched.

Aluminum are usually recycled and replaced when they have a problem. Copper-brass can usually be fixed.

Old electric fans were feeble at best. New electric fans can be pretty darned impressive. The Taurus fan was the first of those. That said, I prefer a clutch fan. I wish that the clutch fan design used on big rigs would make it to light duty vehicles. That would yield a mechanically driven fan that has electronic controls as they work very much like an A/C compressor clutch.

[tgreese]

I think the overriding issues for modern cars are fuel economy, and price. Aluminum is way less expensive than copper and brass, and I believe the fabrication technology has improved significantly wrt building a radiator from aluminum.

Aluminum is a darn good conductor of heat. If conduction were the only issue, we would use silver for radiators. I expect you can easily increase the surface area of an aluminum radiator with denser fins, wider tubes, or whatever, to make up for the loss of efficiency between copper and aluminum.

Re price, not only is the material cheaper, but I expect it costs way more in labor to repair a brass/copper radiator than to scrap the leaky unit and replace it. IME these aluminum radiators only last a decade or two, while a copper/brass cor probably lasts twice as long. Eventually the copper tubes erode enough that the core must be replaced, but again IME that's not economical.

The copper/brass cores are still made if you can find a shop that will remove your tanks/sides and install a new core. It will come from the supplier painted black. A black surface theoretically emits radiation in a broad spectrum and should be more efficient than some other color. Paint is a barrier to conduction though - unlikely the paint is an advantage on balance. I believe the main reason for black paint: so the radiator is mostly hidden behind the grille. Same reason chassis components are black - so they 'disappear' even if in your line of sight.

With the electric fan, I think the overriding issue is fuel economy. For cubic foot of air moved, clearly it costs less (maybe by an order of magnitude?) to drive the fan directly from the engine than to make electricity, store it in a battery, and use it to drive a fan. The gain comes from running the fan so seldom that the less efficient method yields a gain in fuel spent.

Same with hybrid cars - you so seldom need the boost from the electric motors, you can run a small very efficient gasoline engine and save up battery power for when you need more torque and acceleration. On balance it adds up to less fuel cost, even considering the efficiency loss in converting fuel to battery storage.

[ntsqd]

Radiator shops are getting thinner on the ground, but no, it has been my experience that fixing a copper-brass radiator typically costs less than even a chinesium aluminum radiator and the worst case that I've experienced within the last couple of years (core replacement) was slightly less than even.

Even with a clutch on the fan there are times when the drag in the clutch is spinning it when it isn't needed. That drag is a "cost" to efficiency.

Contrast that with an electric fan that is spinning going down the road just from the air moving thru the radiator. It's only drag is a minuscule increase in air resistance of the vehicle moving thru the air (might be measurable, but hardly matters in practicality), and it is likely lower drag than if the fan were held still. Couple ECU/PCM control over the fan and you see a decrease in emissions as well (faster warm-up). The EPA has encouraged the OEM's to get their engines warmed up and into closed loop as quickly as possible, and direct control of the fan is an important part of that.
I can tell you that some electric fans will generate enough power to light a incandescent indicator light that is wired in parallel with the motor's windings.

[tgreese]

The EPA has encouraged the OEM's to get their engines warmed up and into closed loop as quickly as possible, and direct control of the fan is an important part of that.

Interesting. Makes sense.

[Harry Dawg]

Sounds like it 6 to 1, half dozen to the other as far as material type.

I couldn't find a radiator repair shop in my area, so I am currently in the process of melting all of the solder from the top tank so I can access cooling tubes.

Plan is to rod it out for better flow, clean with CLR, and then re-solder the top tank on. Once everything is re-assembled, I'll pressurize the radiator and check for leaks.
Any tips on getting the solder out of the cracks? I've been using flux resin, but the microscopic amount of solder at the bottom of the tank seam is holding strong.

The aluminum radiator from BJ's is $700, so it's worth it to me to fix the one i've got.
Plus, it's just cool re-visiting a "lost art" of sorts. Maybe some kid will ask me about it 40 years from now and I can tell them how to preform a radiator rebuild.

Worse case scenario, I can adapt a radiator out of a CJ7 4.2L fairly easily. (+- $100 on Amazon)

As far as the cooling fans, I previously swapped from a clutch fan to direct drive on our 6.0 Excursion, and experienced a noticeable loss of power. The truck is staying much cooler, especially while towing but it really dulled the performance.

I am wondering how much HP I could gain from an electric fan swap on my Gladiator.

The only thing is, an automatic fan would be out of the option as I only have 1 coolant sensor port and want to retain my temp gauge. Meaning the electric fan would have to be on a switch and would be less efficient having it on all the time.

[devildog80]

I picked up an aluminum radiator on Amazon for $186, and works good with my 401, in my '84 GW.
Plan to have the brass/copper original rebuilt, then its going back in the truck, and aluminum back in the box as a spare.
A friend gave me a new aluminum radiator from his CJ7, that he decided to not use, but size was too small to fit in place with shroud, fan, and radiator mount. A bit shorter and narrower than the FSJ application.

20230930_121029 by Scott Weckerly, on Flickr
20230930_124751 by Scott Weckerly, on Flickr

[Harry Dawg]

They fit well in the first generation FSJ's with the smaller core support. I suspect this isn't the case for the newer FSJ's.

Factory rad on my Gladiator is only 25.5", which is pretty close the the CJ7 Radiator.

@Devildog80 Let me know if you are looking to sell your extra CJ7 Radiator. I have a CJ as well, so I will probobly run it in the Gladiator until I get the copper one rebuilt, and then swap it into my CJ when I rebuild the motor in it.

[devildog80]

I have an '81 CJ5 here with 258, and original OEM radiator in it as well.....still cooling like a champ, so thoughts are to keep the aluminum one for spare as the CJ5 is run primarily off road, and more chance of damage.
My friend said it was only around $100 ish on Amazon, so reasonably affordable, with freight paid through them. Would cost a chunk of that to ship from AZ to GA by itself.