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'64 Skylark Radiator Fan Suggestions


Machine Gun
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My apology in advance for a verbose thread.

 

As I had mentioned in other threads, I replaced the stock two-row radiator on my 300 c.i. engine with a new three-row radiator. I was looking for somewhat better cooling performance, and I'm giving it mixed reviews for the moment. First, bit of history.

 

My stock radiator would maintain coolant temperature at 180 degrees in normal driving conditions (mixed highway and back roads) on a moderately warm day (temps between 70 and 80 degrees), with a 180 degree thermostat. However, under normal driving conditions when temps climbed into the 80s the coolant temp would stay around 190 degrees, and it would creep up to around 210 degrees while sitting in traffic. Nowhere near being overheated, but warmer than I'd like it to be. Hence my decision to upgrade the radiator.

 

I installed the new radiator over the weekend and have been driving the car around town with temps in the mid- to high 80s. There's a noticeable improvement while driving, with coolant temps now staying around 180 degrees, but there's no difference when idling for several minutes. @EmTee had suggested in another thread that the stock four-blade fan might not have the oomph to pull enough air through the thicker core, and that perhaps a change of fan would be needed to improve performance. That indeed seems to be the case. I'm now considering a fan replacement, and I'd appreciate opinions on what type to use. I've not read many glowing reviews on electric fans, so unless someone has a compelling reason that would convince me otherwise that option is off the table. That leaves a clutch fan with its higher blade count, or a mechanical fan with a higher blade count.

 

Buick supplied a clutch fan with the three-row radiator that I'm now using, but that requires a change to my fan shroud. Original clutch fans and matching shrouds seems to be unobtainium. Aftermarket clutch fans are a bit too large for my shroud, but there are 17", five- and six-blade mechanical "racing" fans available from Summit racing and other sources that seem to be what I'm looking for. Blade pitch is not specified, and I think that spec would be important although I don't know what the proper pitch would be for me. My concern about "racing" fans is that perhaps the pitch is tailored to rapidly moving vehicles, and not ones that are sitting at idle. True?

 

So, any suggestions as to how I might increase air flow at idle? 

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Any chance that the gage is wrong?   Even if you have an aftermarket temp gage, it could be giving you a bad reading. 

You did not mention any thought about going to electric fans.   

If your car is an automatic, you can also consider an auxiliary trans cooler.    If you lower the trans fluid temp that helps both 

the transmission life and takes some of the load off the radiator. 

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28 minutes ago, Machine Gun said:

but there are 17", five- and six-blade mechanical "racing" fans available from Summit racing and other sources that seem to be what I'm looking for. Blade pitch is not specified, and I think that spec would be important although I don't know what the proper pitch would be for me.

Are the 'racing fans' you're looking at variable-pitch designs?  (That would explain the lack of a pitch spec.)  I have a vintage 'Flex-o-lite' fan on my '56 Chevy (currently in hibernation).  That one is a fiberglass fan and really works well.  At idle it moves a lot of air and you can watch the blades flatten-out as the RPMs increase.  The similar contemporary fans I've seen are steel, not fiberglass.  I expect they would work similarly, however, I have heard horror stories of them coming apart (blade failure).  Now, this was years ago, but I would be suspicious since metal fatigue is a real concern.  That's the beauty of the old Flex-o-lite design, since the fiberglass composite doesn't suffer from that failure mode.

 

That said, maybe it's possible to scout swap meets and the internet for an OEM clutch fan of the right diameter - even if it is from another manufacturer (e.g., Ford, Chrysler, etc.).  Then, many of the clutches have the same clutch-to-fan bolt pattern, so a Buick clutch might still bolt-up to it.  Another observation is many of the new clutches are drilled for two water pump bolt patterns.

 

Lastly, Barney's suggestion about adding an auxiliary trans cooler is something else to consider.  That would offload some BTUs from your radiator and I'm sure the transmission would also be happy with lower temperature oil...

Edited by EmTee (see edit history)
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1 hour ago, Barney Eaton said:

Any chance that the gage is wrong?   Even if you have an aftermarket temp gage, it could be giving you a bad reading. 

You did not mention any thought about going to electric fans.   

If your car is an automatic, you can also consider an auxiliary trans cooler.    If you lower the trans fluid temp that helps both 

the transmission life and takes some of the load off the radiator. 

It's quite possible that the gauge isn't very accurate since it's not a precision device. However, I'm looking at the performance delta between the old radiator and the new. Regardless of the actual temperature, the new radiator provided a 10 degree drop under most conditions, and essentially no drop at hot idle.

 

I'm not enthusiastic about electric fans for a couple of reasons that include appearance, having to wire them up, additional burden on the charging system, and the lack of universal positive reviews.

 

Good point on the trans cooler, but I'd prefer to avoid the expense and complexity of installing one with uncertain results. I'm confident that it would ease the burden on the radiator as you suggest, but the extent of that is uncertain. An additional consideration would be mounting something else in front of the radiator further restricting air flow, which I think is my issue to begin with. Maybe the benefit of the trans cooler would be canceled out by additional restriction of the radiator. Am I making any sense?

 

My preferred option remains a mechanical fan of some sort, with or without a clutch, depending on what might fit.

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1 hour ago, EmTee said:

Are the 'racing fans' you're looking at variable-pitch designs?  (That would explain the lack of a pitch spec.) 

The fans I've been looking at are rigid types, mainly because I'm also concerned with metal fatigue and I've not yet found a flex fan with fiberglass blades. One of the first types I'd seen is this one: https://www.summitracing.com/parts/aaf-all30103. I'm thinking that something similar, if not that particular one, would help.

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I can understand not using electric fans if you are staying stock, but some of the aftermarket fans are not that attractive. 

Every modern car has electric fans and they are everywhere in the pick-n-pulls.   Also understand if you are paying someone else

to install, and wiring is not that complicated.

Same with the transmission cooler..... almost every truck in the pick-n-pull has a trans cooler and they are better construction than the

aftermarket coolers.....find a truck with a towing package and they have large coolers....also mounting them in front of the radiator is not

affecting engine cooling,  but do not install them in contact with the radiator,  leave 2 or more inches space between the radiator and trans

cooler.     

I live where it has been 100+ every day for the last 37 days and I run a  auxilary trans cooler on everything I own that has an automatic transmission. 

My GMC has a gage for the trans and it has never hit 180 .....even on the hottest days

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Hi Barney:

 

Thanx for the additional information. I've not yet ordered anything so I will reconsider your suggestions since they're coming from someone with direct personal experience. I tend to do things incrementally where possible/practical, so there's little likelihood that I'll do a transmission cooler at the same time as the fan. My approach is to first tackle the issue I started with, which is the fan, and then consider the transmission cooler as a worthwhile enhancement afterward. Whether I do mechanical or electric is under reconsideration, although I'm still leaning toward the mechanical.

 

Whatever I do it will be very soon. My wife and I are preparing for the completion of a trip down Route 66 that I started last year. We're planning to leave next month. The Buick is ready except for the cooling issue.

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Below is a transmission fluid temperature chart that came from some trade magazine. 

Lowering the transmission fluid temperature is cheap insurance against transmission failure.  

FluidChart.jpg

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14 hours ago, Barney Eaton said:

Below is a transmission fluid temperature chart that came from some trade magazine. 

Lowering the transmission fluid temperature is cheap insurance against transmission failure.  

FluidChart.jpg

I saw that same chart on the Hayden Automotive website. I'm processing a couple of things while negotiating with myself over whether or not I will install a transmission cooler. For starters, I'm addressing engine coolant and transmission fluid temperatures separately. Yes, I know they're related, but read on. If the larger radiator and fan combine to maintain my engine temperature at or below 195 degrees in the worst conditions (high outdoor temperatures, stopped in traffic, etc.), then I would not look to a transmission cooler to ease the burden on the radiator as there would be no need to do so. My first objective therefore is to get the cooling system working the way I think it should. A 6-blade fan is due to arrive here tomorrow. While I'm waiting for the fan I'm going to do a bit of research on transmission fluid temperatures.

 

Some of the research I'll be doing will address questions that are floating around in my head as I look at the chart above. If the engine coolant enters the radiator at 180 degrees, the relevant unknowns are the temperature of the trans fluid as it leaves the radiator heat exchanger, and the rate at which the trans fluid is reheated. Those temperatures depend on the temperature and volume of air moving through the radiator, the efficiency of the radiator, the temperature of the trans fluid as it enters the heat exchanger, and the efficiency of the heat exchanger. Driving conditions affect all of that. Does the car have anything in tow? Is it idling in traffic, moving along at 50 mph, or barreling down the interstate at 75 mph? That information can help me determine how much real-world benefit a trans cooler can provide. Certainly this type of analysis has already been done, and I hope to be able to find it and apply it to my particular situation.

 

Trans coolers are not expensive, nor are they difficult to install. Then why am I going through all this? I'm an engineer. It's what we do.

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Good to know the persons thinking on the other end of the line............ while I do not have a engineering degree,

I worked in manufacturing engineering for a total of 38 years and I like to have details and specific information when working on a problem.

One question is..... if transmission fluid is going to a radiator that is at 170-180 F to be cooled,  how hot is the transmission fluid if it is being cooled by that radiator?

In Texas,  I completely bypass the radiator and run the transmission lines to the auxiliary cooler which is setting in ambient air that is never more than 110 on the hottest day of the summer.

That alone is a 60 degree advantage.   Several years back I talked with a GM transmission engineer at SEMA,  he said one reason the trans fluid goes to the radiator is to warm the transmission fluid in cold climates.

Another reason is it is cheaper than having an external cooler when building a new vehicle.    Even in an area that gets freezing weather,  if we are talking collector/show car,  they never get driven in freezing weather

so even in a colder climate they could be a candidate to bypass the radiator. 

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The transmission oil can be too cold; that's why instructions for auxiliary coolers typically recommend installing in series with the radiator cooler.  That brings the transmission oil up to operating temperature quicker.

 

image.png.a706fff30cd93a9bbd9aa23c128b7b70.png

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55 minutes ago, Barney Eaton said:

Good to know the persons thinking on the other end of the line............ while I do not have a engineering degree,

I worked in manufacturing engineering for a total of 38 years and I like to have details and specific information when working on a problem.

While you may not have an engineering degree, you think like an engineer (that's a compliment). Let me be clear...my engineering degree is in electrical engineering, so I am not qualified to speak with authority on this subject. I brought up my engineering background only to provide insight into how I think. You first establish that a problem indeed exists, and then you use your skills to design mitigation measures. But that's only the start of the process. After you're done using the calculator, you prototype, test, analyze, and then apply what you learned to refine the design, and then reevaluate. I'm at Step One right now...identifying whether there is indeed a problem that I should address, or at least whether there would be substantial benefit to be gained by installing a cooler. It's unlikely that I will go much beyond Step One. If I think there could be a problem, or if I think it would otherwise be worthwhile to install a cooler I'll do so and not look back. 

 

You live at one end of the CONUS climate spectrum, while those in the Dakotas live at the other end. I live somewhat in the middle where such temperature extremes, while not unheard of here in NJ (except perhaps for temps in the -20s), are certainly not the norm. Hence my choice to cool or not cool may not be as clear as yours or someone who lives in Pierre.

 

It's possible that I may not readily find enough information on the web to make an analysis. In that case I'll simply make a judgment call one way or the other based on your input, whatever information I can dig up, and my gut feeling. In the grand scheme of things it's not worth too many hours of my time researching this in order to save $100 on a cooler. Sure, the easy thing to do is throw on a cooler, but I'm inquisitive. I appreciate the discussion.

 

@EmTee Yes, I also came across information that says one can excessively cool a transmission. In your case and mine that's unlikely because of where we live and how we drive. If I eventually install a transmission cooler I will do so in accord with manufacturer recommendations, i.e. I will use the secondary cooling method illustrated above. 

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The new fan is on, and I road tested the car this afternoon with temps in the low 90s. Coolant temperature stayed at 180 degrees while driving, and rose to 205 degrees during extended idle while in gear (it had been 210 degrees prior to the new fan). I realized a five degree temperature drop with the new fan. Less of a drop than I had wanted, but I'm confident that the car won't overheat in severe conditions.

 

My next, and final cooling-related project will be to install a transmission cooler.

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Late to the discussion, but here are my experiences from a while back . . . .

 

When I got my new '77 Camaro 305, I was a bit pleased to see that it had a FACTORY flex fan rather than the normal fan clutch.  It did move a lot of air at lower speeds, which I liked, but had a bit of wind noise to it (as any somewhat fixed-pitch metal fan would).  But as the car aged, it began to get a "creeping heat" situation at highway speeds, but never really got past 215 degrees F with the stock 195 degree F thermostat.  From the radiator filler neck, the core looked clean, so I suspected it might be the flex fan feathering out quicker with its mileage (about 75K at that time), but it still acted normally and moved a good bit of air.  So I got a new one, with no change.

 

I replaced the OEM radiator with a 3-core Modine for the car.  That helped, but the issue eased back in.  So that sent me on a mission to research factory fan clutches and fans.  I went toward the "Police and Taxi" section of the Chevy parts book.  Then to the ACDelco Fan Clutch Catalog (with SPECS on "center hole", shaft length, and such).  So I could check the OEM items against the more HD Police items, too.  I don't really recall where I ended up, as to application, but I ended up with a fan clutch from a Chevy pickup truck or a mid-'80s Caprice and the (seemingly small diameter) fan to match.  END of issue until the 3-core Modine got "accumulation" in its lower core area.  Then a new ACDelco "upgrade" (read "composite") radiator from a '87 El Camino V-8, which took all of 45 minutes for the 180 degree F thermostat to open on a 75 degree F spring afternoon.  END of issues until that radiator got "accumulation" in its lower area, so a new one of the same application was ordered-up and things stay cooler like they should.

 

That particular ACDelco Fan Clutch catalog is now archived somewhere, so it's not readily available, but the Hayden catalog is online with similar information on the specs of their products.

 

First thing to do is to take the width and height specs for your existing radiator and see if a more modern application exists, for which a plastic OEM-style fan shroud might exist.  IF the factory a/c option had one, possibly somebody could measure theirs and post some pictures of it with measurements of the hole diameter and related fan issues?  From that point, a search of later-model applications (with vertical-flow radiators, not specifically Buick vehicles) might yield an incorrect-but useable shroud situation?

 

But as you've increased the cooling potential of your system, a system which Buick validated for production, it could well be that the front-side of things is not where the problem with the operating temperatures might be.  Rather, the real issue might be in the "back end" of things, in the coolant passaged in the rear of the cyl block.  The rear of the block is usually lower than the front, so that's where things "settle-out" and accumulate.  Over time, reducing coolant flow and causing higher low-flow operating temps, usually, by observation.  Which means . . . knocking out the core plugs from the sides of the block and flushing out those passages to regain the designed-in flow capabilities.  Then put some new brass core plugs in, add the necessary coolant concentration, ensure the radiator cap is good, and you should be ready for unlimited use for many years.  BUT that can be messy and might also qualify as "hazzardous materials", so some containment of the fluids and such might be needed.

 

In the mean time, head over to the RockAuto.com website and check what they sell for fan clutches and fans for your application.  The fixed-blade "racing" fans are to be stayed away from.  Many are molded fiberglass, fwiw, but they do tend to have decent reliability.  Their only real purpose is to move enough air at low engine speeds to keep the engine cool in the staging lanes of a drag strip.

 

On our '66 Chrysler, the factory fan clutch was needing replacement and I really didn't want to put another one on, so I found a vendor and got a stainless steel Flex-A-Lite fan for it.  This was in about 1975.  After tweaking the placement, it was still very noisy, even with the 2.76 rear axle ratio.  By 60mph, it kind of sounded like a jet getting ready to take off, in the interior.  It was moving air, though, enough that I suspected it might be helping move the car down the road, but NO increase in fuel economy was documneted.  BUT, after driving freeway speeds for about an hour in July TX heat, when I got home, I could raise the hood and remove the air cleaner with my bare hands and NOT feel an ugent need to set it down quickly.  I was impressed with that.  As if the air cleaner was at less-than-ambient outside temperatures, remarkably so.  BTAIM

 

BEFORE jumping down the Flex-A-Lite "hole", I talked to the local Chrysler dealer's mechanics about the fan clutch.  One mentioned that he had "made his fan clutch solid" by using a punch and hammer to lock the two parts together.  I used a bigger Phillips-head screwdriver and dimpled each side of the metal fluid reservoir on the front, effectively increasing the fluid pressure in the unit, which made it un-couple later, which kind of did the same thing in a different way.

 

After I had had enough of the jet engine sounds under the hood, I eventually got a new fan clutch and put it all back right.  Took the flex fan back to where I got it (to an understanding owner, who fully-refunded the purchase price), and was quiet and well again.

 

When you do get an OEM-style fan/fan clutch/shround assy on the engine, it will look better and should perform better than "when produced", I suspect.  It seemed that many GM divisions had open-air fans in the earlier 1960s, probably good enough but not as good as they could have been (at a little bit more cost to get the cars to the end of the assembly line, back then).  So it seemed that as competitors had fan clutches and fan shrouds, GM brands did not have similar things until a few years later, when they could be better-covered in the selling price of the vehicle, by observation.  So, you end up with something not "production-accurate", but looks OEM with OEM-level shroud, you can tell people that that is how they should have been built in the first place . . . or it is "factory experimental" or was a "factory fix" mentioned in an old TSB you came across.

 

As to current fan clutches, unless you might get one ($$$) from the repro people, they will all have the 4 slots on the water pump side of things (i.e., universal flange), but still have the centering hole in the middle of that flange (for correct location).  Most of those holes (factory-spec) usually match Chevy applications, so that can make things easier.  From there, you have the various shaft lengths between the water pump and where the fan bolts onto the clutch.  THAT is important, although a bit shorter can work, too, as long as nothing hits, of course.  But the KEY thing is to determine what the factory would have used for a fan clutch in the first place (i.e., shaft length) and what kind of fan shroud might have come with the engine when factory a/c was ordered, too.  From there, a 5-7 blade factory metal fan of the correct diameter will complete the package.  UNLESS an observer might know what they are looking at, they might not really suspect anything might be different from actual production.  Key thing is to keep it looking "All GM", which should be doable.

 

From my experiences,

NTX5467

Edited by NTX5467 (see edit history)
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@NTX5467 Thank you for the detailed account of your experiences with cooling system issues. I did look into what the factory used on Skylarks equipped with the heavy-duty cooling option, and OEM-type parts are largely unobtainium, except for the three-row radiator that I recently installed. I chose a rigid, six-blade steel fan with the same 17" diameter as the stock fan so it would fit into my shroud. I'm done with 

 

I had thought of the possibility that there is some accumulated crud in the block behind the Welch plugs, but the best I could do was to have the system reverse-flushed last year. No, that wouldn't have flushed out everything at the rear of the engine but it was better than doing nothing. I may eventually tackle that job myself if I can access the plugs well enough to remove and install new ones with the engine in the car. Otherwise, things will remain as they are.

 

Bear in mind that the car never had an overheating problem in the nearly eight years I've owned it, and I've driven it all types of traffic and weather conditions. I only started this effort when I was considering installing A/C in the car. When I scrapped that idea I decided that upgrading the cooling system anyway would be a good idea.

 

That $40 temperature gauge cost me about $800 and bunch of time 😖. Except for a possible flush of the block I've done all I plan to do with the cooling system.

Edited by Machine Gun (see edit history)
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If my memory serves me correctly, my ‘64 Skylark with 300cu in hi comp 4bbl Power Pack motor and factory air conditioning was fitted with a multi blade metal fan (possibly five blades) with fan clutch and fan shroud over a three core conventional radiator,

 

I gather as it lived in Southern California all its life, that cooling system would have been sufficient, especially as it was black on black.

 

It would have been engineered to have sufficient cooling when new, so the only degradation would be accumulated rust and scale and decreased flow as time goes by.

 

Not a big fan of alternative solutions when a bunch of factory engineers worked on the design to get it correct back in 1964. Would a fan and clutch unit from an a/c car be a better solution?

 

Just my thoughts 

Rodney 😀😀😀😀😀😀😀

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48 minutes ago, rodneybeauchamp said:

Not a big fan of alternative solutions

 I made a pretty good living for 50 years by reversing alternative solutions from power plants and buildings.  I have had the same good luck doing that with cars.

 

A modified car I bought is being delivered on Saturday and I spent a good part of the weekend planning how to remove the mods.

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8 hours ago, rodneybeauchamp said:

It would have been engineered to have sufficient cooling when new, so the only degradation would be accumulated rust and scale and decreased flow as time goes by.

I agree completely on both counts (cooling would have been sufficient as designed, and degradation due to accumulated crud in the block). However, while I acknowledge that I may have some crud in the block, what temperature would the engineers have considered acceptable under the hottest conditions? My car in traffic with outside temps in the low 90s seems happy to peak at 205 degrees, which is nowhere near overheating. Would the engineers have considered that acceptable? Maybe, maybe not. Regardless, it's acceptable to me. Had I not replaced the idiot light with a gauge I'd have been fat, dumb, and happy all along, just as I would have been back in 1964. Ignorance is bliss.

8 hours ago, rodneybeauchamp said:

Not a big fan of alternative solutions when a bunch of factory engineers worked on the design to get it correct back in 1964. Would a fan and clutch unit from an a/c car be a better solution?

I'm not a fan of alternative solutions either, for the very reason you mentioned. The only non-factory options I installed on the car are a fuel pressure gauge to tame the modern mechanical fuel pump that was causing my carburetor to puke (described in another thread), and the conversion of the brake system to a dual-circuit system that first appeared under federal mandate in 1967 if I'm not mistaken. The new radiator is identical to the Buick factory H-D radiator in size, style, number of rows, and material (brass).

 

If I properly understand clutch fans, they offer no benefit while engaged at idle or while driving at slow speeds over that of a fan of comparable size with an equal number of appropriately-pitched blades. All's been well and cool while driving. I wanted to minimize temps at extended idle. Accordingly, I replaced my four-bladed fan with a six-bladed one. Again, I'm OK at a maximum of 205 degrees on the relatively rare occasions I sit in very hot summer traffic.

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12 hours ago, Machine Gun said:

My car in traffic with outside temps in the low 90s seems happy to peak at 205 degrees, which is nowhere near overheating. Would the engineers have considered that acceptable?

Since that light would not come on till the engine temp was  245° the answer to this question appears to be : yes. 

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13 hours ago, Machine Gun said:

I wanted to minimize temps at extended idle.

I seem to recall mention of an idle minded engineering group at GM who made an in depth study of spark plug tips to address that. As long as though delicate little tips looked good after being pulled from their fiery home I'd be OK with things.

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