jpc647

Do you guys install some sort of spacer at the end of the water pump when changing fans? I got one It'd like to try, and when I went to install it, I noticed the fan is no longer going to sit about 1/2 in the shroud, it's going to be closer to the motor, now negating the benefit of the shroud.

If the fan clutch is super nosey, it'd still like to use the 6 blade fan instead, it must pull more air than the 4 blade.

Sure I could drill the rivets out of the OEM one, but I thought there must be other people who ran into this.

ELY442

Please state, year, make, model, and engine. I have a 70 Cutlass with a 350 and 455 motor and recently I swapped it over from a 6 blade to a 7 blade with a clutch and without using a spacer. The fan stands about 1/2 - 1" into the shroud, (Im just guessing).

2blu442

The fan clutch should not be noisy. If yours is then I'd encourage you to buy a new clutch. I've seen people swap the complete clutch fan for the 4 blade with spacer successfully. I've never seen anyone try to use the 6 or 7 blade clutch fan without the clutch. You may have to keep the clutch assembly with the 6 blade fan for it to fit/perform correctly.

John

MDchanic

Do not mix and match.

Either use the 6- or 7-blade fan with the clutch, but without the spacer, or use the 4-blade fan without the clutch, but with the spacer.

If the entire assembly is too short with the clutch, then the odds are that your year/model.engine combination used a shorter water pump with the 4-blade fan and a longer water pump with the clutch fan, so you may have to go to a different water pump.

If you use a 4-blade fan with the clutch, the fan will not have adequate resistance to make use of the clutch, and it will just spin at the "fully engaged" setting.

- Eric

jpc647

It's not noisey, but I was saying, if i is, it'd like to upgrade from the 4 blade to the 6 blade. More blades, more air.


It's for a 1972 Cutlass, 350ci motor. The fan with fan clutch fits, it just barely goes into the shroud. Like maybe 1/2. It'd guess 3/4 of the fan isn't in the shroud, so I was going to buy like a 1" spacer to put the fan back in.

Why can't I put a small 1" spacer between the water pump and the fan to put the fan back into the shroud completely? I'm sure this fan came off a car with heavy duty cooling, etc. But my car runs around 200-210 and I thought this fan would help bring that back down. A fan swap is a lot easier than trying to upgrade from a 2 row radiator to a 4.

MDchanic

I guess you could. There's no technical reason not to.


And here's where your idea goes off the rails.

If you need a bigger radiator (and you've eliminated other problems, like an inferior water pump, a bad thermostat, a collapsing lower hose, or rusty water passages), then a bigger fan won't help you.

A radiator that is too small will show its weakness as the engine makes more heat, generally in sustained highway driving in hot weather, especially on long uphill runs.

A fan that is inadequate will show its weakness when the car is moving slowly, such as when stuck in traffic.

If the fan is bad, then as you get on the highway and speed up, the engine will cool down, because the airflow past the radiator is greater than the fan could provide anyway.

If the radiator is bad, then it will generally cool just fine in traffic and around town, because the engine is making much less heat then.

You need to figure out where your problem is before you start throwing parts at it, unless you've got a lot of spare money.

- Eric

Indy_68_S

You could. This is the route I was looking at. I got (have no memory of where) a 6 blade clutch fan that fits my '68 shroud (which is smaller than subsequent years) and my car, while it came with a 4 core rad, had the 2" spacer & 4 blade fixed fan from the factory. A 1" spacer positions the 6 blade about perfectly in the shroud with my shorter 4blade/2"spacer water pump. I never had cooling problems, but liked the idea of the 6/clutch fan. Stopping me was I haven't found an easily obtainable proper 1" spacer.

I would not try to use the 6 blade with the fixed spacer.

Like MDchanic said, the 'real' 6/clutch installation is the longer water pump that negates the need for the 1" spacer and if you're having cooling issues, I'm not sure the 6 blade would cure it.

jpc647

Why wouldn't you use the 6 blade with a fixed spacer? You can easily buy a 1" spacer from Advanced Auto, bolt the fan and spacer to the water pump and call it a day. Why isn't this spacer "proper"?

http://shop.advanceautoparts.com/p/i...507&showTitle=

MDchanic

Because without a clutch, the fan will be "On" all the time, creating a sound like a B-29 taking off, and robbing several MPG while driving.

- Eric

jpc647

At least the car will sound fast! Ha. I'm kidding...

Understood. I thought he was saying don't use the 6blade/fan clutch with a spacer. I can understand why you wouldn't want to use a 6 blade without the fan clutch.

MDchanic

The possible complication of using a spacer is that the clutch fan has its fastening location (on the end of the clutch) about 3" beyond the fastening location of the clutch to the water pump (or spacer), and the entire assembly has a great deal more mass, both total, in the form of more and larger blades, and central, in the form of the fan clutch, so that if there is any lack of concentricity or deviation from parallel in the spacer, the resulting imperfection in balance could cause big problems at high RPMs, when you least want them.

If the spacer is really well machined, this shouldn't be a problem.

- Eric

Indy_68_S

Yep. That's what I meant.

I assume the reason for longer WP snout for the 'real' 6/clutch installation is to get the WP shaft front bearing closer to the fan for support. I realize that adding a 1" spacer to a short WP with the 6/clutch assy goes against this. My thought is that the clutch assy somehow mitigates this a bit by having more centralized mass & dampening from the fluid coupling to the blades.

As far as that AutoZone spacer, I've seen those. I would rather have something solid with holes, not slots - and that spacer says "For use with Imperial Flex fans" which I assume weigh much less than a 6 blade/clutch assy.

jpc647

I understand what you're saying. And sure, the fan clutch is heavier than a 6 blade fan so that does make sense.

I did try the spacer, and it fits, but the problem is the shaft in the middle just barely long enough to press the fan onto. I wasn't comfortable with that so I didn't install it. Maybe I'll just mill from from aluminum stock at work.

My clutch fan fan blades sit almost perfectly half in the shroud and half out. It'd prefer the entire fan is in the shroud, but without a spacer, or without changing all the pulleys on the motor(not going through that trouble, it'd rather replace the radiator), it is what it is.

But, the car does run consistently 5-10* cooler in traffic with the fan clutch. So it makes a difference, and it was in the shroud more, it might help that much more.

On the machining note, many of the pulleys on these older cars aren't perfectly concentric. They "wobble". Even if a spacer is "close" within a few thou, it should be okay. For a measure of safety, I'll use Grade 8 bolts instead of the typical grade 5.


This has got me thinking though, the pulley on the 5 1/2" or 6" pump, are they offset more? It's not just as simple as buying a different pulley and replacing the pump right? They were close to, if not the same pulleys?

I mention this, becasue I do have an AC Delco 6" water pump NIB because it didn't fit and I couldn't return it.

olds 307 and 403

I went through everything possible with my 403 and cooling issues. From under drive pulleys to a bad high flow thermostat that flowed around town but closed up at speed. I assume the car runs cooler at highway speed then around town? I think you are best to make your own solid spacer to keep the fan stable. Good luck and show some pics of what you come up with.

MDchanic

Yes. The pulleys are different for different setups.

Here's a picture:



You will notice that cars without A/C or HD cooling used water pump and crank pulleys with two sheaves, while those with A/C, HD cooling, or HD alternator used pulleys with three sheaves.
These pulleys will not line up with each other if mismatched.
This is why it is generally recommended to change all of the accessory pulleys as a unit, if going to a different configuration.

- Eric

BlackGold

You'll also notice that cars with A/C or HD cooling used pulleys which drove the fan faster than the crank, because they knew there would be slippage in the fan clutch, while cars without A/C drove the fan slower than the crank.


Go ahead and mix and match whatever pump and pulley and fan and clutch and spacer and shroud and radiator you want. The engineers were stupid and didn't know what they were doing. The factory didn't care about warranty costs or unhappy customers either. Besides, none of this matters when you only sell 100,000+ cars a year.

jpc647

Is this a poor attempt at sarcasm? Because there is absolutely no issue installing a shroud on a car that didn't have one factory. Installing a fan clutch on a car that came with a solid 4 blade is also common, and clearly not a problem.



I ended up starting by making a new pressed in bushing for the fan spacer I bought. My machinists didn't have a ton of time to make a whole spacer, but the small pressed in bushing was something he could make without raising any eyebrows. I'll attach some photo's. The original bushing is sitting in the side for reference.

Yeah, the car runs fine on the highway. And even around town it's not a problem. I guess, I really don't have a problem until I sit in traffic for periods of time on hot days. I've never had a problem like overheating, this was just a cheap/easy improvement. It'd love to put a 4 core radiator in the car, but buying a new top plate, new cradles, the radiator, and everything, I just can't justify it, we're talking $500 plus welding in the cradles. And it seems silly to replace and old 2 core radiator with the replacement aluminum single core. Replacement 3 cores are available that will fit, but they are pricey. And I guess I'm too cheap, because they are in the ballpark of the 4 core replacement cost.

20161208_152221_zps9ayxbvat.jpg

20161208_152215_zpsdeeqeqnh.jpg

I agree, ultimately I should use a solid spacer and grade 8 bolts. But the Imperial Fan spacer will be fine for initial testing. If I put it on the car, the fan will sit further into the shroud, and then I can see if the temperatures drop even more. If they do, I'll machine a piece of 3" stock down to 2" and make a solid spacer. If the temperatures remain where they are with the fan clutch, I'll remove the spacer, and be content with the fan clutch fan 1/2 in and 1/2 out of the shroud.

MDchanic

Naaah. That wasn't sarcasm.



Then you don't need a new radiator - your radiator is working fine.
Your problem is with your fan (and/or some other restriction, such as leaves or dust stuck between cooling fins, which is unlikely).

This spacer should fix your problem, but keep an eye out for any eccentricity as the fan spins.

- Eric

jpc647

Yeah, there doesn't seem to be any restrictions on the radiator. It's older, but I boiled it out a couple years ago, and there isn't really any crud in it anymore. Maybe next summer I'll replace the radiator hoses, they are 5 years old now, and the bottom one looks a little worse for wear. But it's got the spring in it, so I really don't think it's collapsing. The car has always run this way, this isn't a sudden change, I'm just finally trying to improve the situation. I've even listened to the water pump with a stethoscope to listen for any irregularities, and nothing.

BlackGold

It's my opinion that radiators have a limited life. Boiling it out, rodding it, whatever, will never bring it back to new. Oxidation (not just crud) builds up inside the tubes, outside the tubes, and on the fins. And the bonds between tubes and fins lose their integrity and thermal conductivity. You might be surprised how much better a new core or new radiator cools.


And while, yes, a cooling problem at idle generally means an airflow problem, a better or bigger radiator ALWAYS helps cooling -- not just on the highway but also while idling.

jpc647

Sure, i don't doubt that. I guess I just don't want to spend $300 on a radiator that "might" cool better, but also, might not.

oldcutlass

I don't see an issue with using a small spacer as long as there are no vibrations. If your reaching 200-210 at idle or in traffic I see this as normal if your running a 180 thermostat and the temps recover quickly once you start moving again.

MDchanic

No.

He has no cooling problems when under load, so long as he is moving fast enough to get air through the radiator.

A bigger radiator with inadequate airflow through it will cool no better than a smaller radiator because in this case the airflow is the limiting factor, not the radiator.

He is getting adequate cooling from a 2-row radiator. Going to a 3-row or even a 4-row will not make a difference in the problem he is having.
Improving his fan, whether by installing a 6-blade and clutch, installing an adequate electric fan, or even installing an adequate flex-fan, will.

- Eric

jpc647

Nothing noticeable. I took a video, my OEM pulley's are way more "out of balance"(they've always been like that" than my spacer.
I don't see 200/210 as an issue either. But the concern is, it will want to keep going. It'll go 215/220 if I sit long enough. Usually by then, I'm moving. But what if I get stuck, do I really want to worry if it'll keep climbing? It will recover relatively quick ones I'm moving 15+mph or what not. My temp gauge is a recent addition, I just never knew how hot the car was before. Now I know, and this is sort of preventative.

The clutch fan def. brought running temps down 5*+. But the fan blades are only half in the shroud, half out. Maybe my spacer won't have any effect at all. Maybe bringing the fan the 1" closer will do nothing. And if that's the case, I'll happily remove it. Hell, it cost me $11 plus some machining time at work, I figured it's worth a try. Maybe bringing the fan closer to the radiator will bring running temps down even more! (Or so a man can hope).

I would think the 3 or 4 row would slow the problem down, ie take longer to heat up, but inevitably, it would still happen.

MDchanic

X volume of air at Y° below engine temperature can only absorb Z amount of heat before it reaches engine temperature.

If the air is leaving the rear side of the radiator at a temperature that is close to the temperature of the coolant (as I believe), then increasing the size of the radiator will do nothing, as the amount of air that is being pulled through can still only absorb the same amount of heat as before.

- Eric

oldcutlass

Improper air flow + thicker radiator = bigger problem

jpc647

Spacer seems to spin true. The factory pulley is more "out of round" than the spacer and shaft. Is this the quality engineering you were referring to blackandgold? haha (it's always been like that, since I've had the car).

Damnitt. Photobucket does seem to like videos....

http://vid478.photobucket.com/albums...psktmiy6bi.mp4

http://vid478.photobucket.com/albums...ps7muwutgb.mp4

BlackGold

Sigh. No one understands heat transfer. While low airflow might be the dominant factor in a cooling problem, a larger radiator will ALWAYS improve cooling. Given the exact same, low airflow through a 2-row and a 4-row radiator, the 4-row will transfer more heat from coolant to air. It has more surface area inside in contact with the coolant, and it has more surface area outside in contact with the air.


Having said that, I'll agree that a larger radiator may not be the best solution for the OP. I'm just saying it cannot hurt (other than his wallet).

MDchanic

Grumble.

A large radiator that has its surface area exposed to ambient air (such as a radiator in your house) will be able to transfer more heat as it size and/or coolant flow rate increase, because the heat of the radiator will increase convection around it, which will increase the flow of air over it, which will increase heat transfer.

An automotive radiator (or heater core, or a household central A/C evaporator), though, does not have its heat exchanging surfaces exposed to free-moving ambient air (unless the car is moving, but we're talking about a cooling problem that happens when stopped).
A car radiator has it heat transfer areas inside, with air passages (between the cooling fins) about a sixteenth of an inch wide and from 1" to 3" long, and they are oriented horizontally, to take advantage of air movement when the car is moving, rather than vertically, to take advantage of convection.
Aside from a certain amount of direct radiation from the tanks, and some slight convection across the tanks and the outside surfaces of the core, the amount of air that is available to absorb heat from the radiator is extremely limited.

If you add in a weak cooling fan, pulling a small amount of air through the core, you have a fixed, small amount of air passing through, with a limited temperature gradient (in Arizona, assuming a 100° ambient temperature, you have about a 90° gradient). So, if you've got a small amount of 100°F air entering the front of the radiator and being pulled out through the rear, there is a very limited amount of heat that that air can pick up, and in practice, we have a car whose temperature increases under these conditions, indicating that the volume of air that is passing through the radiator has absorbed all of the heat that it can, and that there is extra heat that it cannot absorb, and that is being left behind in the system.

If you double the heat exchange surface (by going from two rows to four rows), you will not gain any significant cooling under these described conditions, as the volume of air that is being pulled through the radiator by the fan was already unable to absorb all of the heat that was offered to it. If the air was already heated from (hypothetically) 100°F at the front of the radiator to 190°F by the time it traversed the 1" thickness of the core and exited the rear of the radiator, then it will still be heated to 190° by the time it has travelled halfway through the core of a 4-row radiator, and will not absorb any more heat as it passes through the remaining 1" of the core.
Now, if the engine begins to overheat, and the temperature goes up to 130°F, then maybe that 4-row radiator will be able to pull the temperature down very slightly more because of the increased gradient, but not very much, and this gentleman's engine doesn't get that hot anyway.

So, while I cannot disagree that, all other things being equal, a larger radiator will always be able to cool some amount more, my point is that in practice, and in this poster's specific situation, any increase in cooling that you could measure under laboratory conditions would be undetectable in practice under the actual conditions encountered as installed in his car.

I think it is clear that we are arguing over trivialities, and that both of our advice to the poster is the same, but I am concerned that saying that a larger radiator would increase cooling under his conditions might mislead him or some future reader to go out and buy a radiator, when, in fact, all he needs is a better fan (or to just keep moving! ).

- Eric

Ozzie

The resolution of the question may be contained in the items listed below, but before starting be sure you have ample time and headache deterrents available. This might have even been a challenge in the heat transfer classes I had in engineering school.

https://engineering.lamar.edu/_files...or%20Final.pdf

http://iosrjournals.org/iosr-jmce/pa...e2/RDME-11.pdf

A more empirical approach can be seen here:

http://www.clubhotrod.com/shop-talk/...ator-size.html

olds 307 and 403

It depends on radiator design, a big 2 core can out cool a 4 core. I had an aftermarket 2 core out cool an aftermarket 3 core, both aluminum. I would go with a 1" or 1.25" core, 2 core aluminum rad over a similar sized 4 core any day. Lighter and air should flow through better.

steverw

You said your fan was half in and half out of the shroud, but you wanted it all the way in the shroud. I was always taught that the fan SHOULD be half in and half out. Thats just the way i learned, other wise i have no idea if all in would be better. My 67 has a factory shroud with 6 blade fan and clutch and its half in and half out. It will idle in my garage all day at 180 degrees with no other air flow except what the fan is pulling. It has an original, rodded out 3 core rad.

BlackGold

Eric, thanks for taking the time to explain. I understand completely what you're saying. I'm just having troubles believing that the airflow is so low that it actually does absorb all it can, sending the gradient to zero. But you're obviously right that you reach a point of diminishing returns where it's more important to move more air than to have more surface area.

MDchanic

You're welcome. We can't get anywhere on here if we can't explain the reasons why we believe that a certain process is occurring in a certain way.


Well, that's a relief - I'm never sure whether I make sense to anyone but myself.


Well, of course, without making proper and accurate measurements, we cannot ever know that, but those measurements would not be hard for JPC to make, if he chose to do so (he'd need an accurate and responsive temperature probe, but those aren't expensive). I'd buy him a 6-pack if he did, and posted the results.

We all agree that the key is forced air flow in this particular case.

The only other thing I'd add is that if the fixed-fan pulley system turns the fan much slower than the clutch fan system, then that may be his final obstacle to achieving good cooling. I do not know the diameters of the crank and water pump pulleys in both cases, though there are some here who do, and if we had that information, we could provide an educated guess as to how well this modification will perform.

- Eric

olds 307 and 403

The non A/C pulleys are definitely more under driven, means less cooling.

BlackGold

Hence my earlier "poor attempt at sarcasm."

MDchanic

You rotten, mean, sarcastic guys are all alike.

But, yeah: Increase fan speed, fan blows more air.

- Eric

mrolds69

Jim...I didn't read this whole thread closely, I didn't look at my own cars, but I believe this is true. There are also the radiator side flaps and the lower flap spoiler...don't know if they are there or not. Also...inner fender flaps (lack of) can mess with the flow. Just some thoughts, no engineering degree here! See you at the banquet maybe....

Ozzie

The positioning of the fan in relation to the shroud "might"
be dependent on the design of the shroud.
One rule might not fit all circumstances. Here's one placement
which was done by Oldsmobile in the mid 1950s.



1955 Oldsmobile with C.A.C. (car air conditioning)



And here's a home made one on a mid 1960s Oldsmobile 442.



1965 Oldsmobile 442

Both seem to work reasonably well.