radiator fan ?

    
Here is a crazy question but I'm going to ask anyway.
I have a 1992 Chevy K 1500 5.7L Engine, it has the old style raidator
clutch and fan.
My friend has a 1999 Chevy K1500 5.7L engine, and it has radiator cluch and fan too but its a differne design, both the clutch and fan are different.
My question is this: Is the new style radiator fan better at pulling air across the the radiator. I noticed that the OEM GM fan is similar to the style used on the japanese products.. (large mult-blade plastic type fan) which appears to me to work very well. My toyota pickup had a simialar setup and I don't think you could make it run hot no matter what you did..
I realize that the pulley system between a 92 and 99 truck are different, I've not checked the trucks to see if the fans turn in the same direction or even if it would be possible to install the 99 clutch and fan along with the water pump pully on a 92 model truck, or for that matter would it make sense.
ITs getting hot here in AL and I noticed today when I had a long wait and extended idle with teh A/C on the truck was approaching 210F. While I realize thats not excessive I wonder if there are other solutions that might cool better. The truck has a large radiator , core is approx 19*34 (be-cool) radiator and it also has a full shroud.
Once the truck is moving it runs around 180 to 190 with the a/c on. I have a 180F thermostat.
Any comments?
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Elbert Clarke
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? is your truck overheating ? is your a/c cooling ? has your truck been reliable ? think about it your truck has been the most reliable car or truck on the road ?think about$$$$$$$$$$ ?truck payments in a year ?think about repairs
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think about reading his question.
He was considering retrofitting the new style fan, not buying a new truck.
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added comment clean out between radiator and condensor and if still overheat please bring vehicle to tagauto 110 8th street or call 256-5390471
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"ob1" wrote:

His problem is not bad enough to require a trip to a shop as it cools fine on road when moving. It just may needs a fan that is a bit more agreesive at a idle. 210 degrees at a extended idle in traffic with A/C on is not cause for alarm. WHo many blade is the fan on it now?
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wrote:

Yes, I agree that 210F on extended idle in mid-summer 90F+ ambient weather is not that serious. I have a 6 blade (aftermarket) flex-a-lite clutch fan with a HD OEM fan clutch, along with a full shroud and a large aluminum radiator.
The truck runs cooler now than when it had the full set of OEM parts.
In order to run the larger / thicker radiator I had to go with a shroud off a 99 year model truck because the stock shroud on my 92 would not allow the mounting of a thicker radiator.
The fan is approx 19" in "width" and fits depth-wise rather well in the shroud. There is about a 1" gap between the edge of the radiator fan blades and the lip of the shroud.
I don't even know if you can improve on this much at all....
The factory OEM fan blade only had 4 blades on it and I thought it was a piece of crap, so it went to the dumpster.
I would like to move more air across the radiator at idle or low RPMs. I'm debating on adding an electric fan.
In the high temps we are seeing in AL now...you can hear the clutch fan kick on often in low speed traffic. Of course these fans don't do that great of a job at low RPMS or idle. That was the basis of my question about the new "style" fan thats on the 99 year model trucks and most likely others that I'm just not aware of.
I'm not aware of a clutch fan that will pull more air than the fan I have now on a 1992 model truck. I would guess that some fans may have a different pitch of the blades which allows for a more aggresive fan performance once engaged. I did ask onetime of the local GM dealer and they only show one style of fan for a 1992 pickup.
I'm not going to run a "flex fan" because they make to much noise and I'm of the opinion that they also perfrom poorly at low engine rpm.
I know GM make an auxillary electric "pusher" fan that came on some of the one ton and 3/4 ton trucks of a similar year as mine. It was on the passenger side of the radiator and was a "pusher" style and mounted in front of the A/C condensor on the RH side. I don't know how well these performed since I've never owned a truck with that on it. I do know there is not much room at all between the A/C condensor and the grill, so you are very limited in what you can do.
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Elbert Clarke
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The flex fans work best in lower RPM ranges -- as the RPM increases, the fan blades "flex" to offer less resistance thereby decreasing the load on the engine. Yes, they are noisier because of their blade configuration which are aggressive.
When viewed from the side of the vehicle, no more than half of the profiled fan blades should be outside the fan shroud lip for optimum performance.
A 1" gap between the tip of the fan blade and the fan shroud maybe affecting the fan's performance a bit but too small a gap will cause scraping against shroud as the engine rocks up and down. Seal off gaps/holes between the fan shroud and rear of radiator to improve efficiency of the fan.
Install a pusher fan in front of the radiator -- it will only help. Install two if you have room.
There are extreme duty fan clutches and extreme duty fans available.
Install an auxiliary cooling system (JC Whitney sells medium and large kits). This is probably the cheapest option with the best bang for the buck.
Good luck, Franko

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wrote:

Yes, I had a flex fan for a short period of time on a 78 z/28 i once owned. WHile the fan does perform well, when I'm talking low rpms I mean at idle and just off idle. Flex fans cool rather well in their RPM range when you have them setup properly. I just don't care for them.

I would say that at least 75% of the fan or more is within the shroud.

The fan shroud is off an 99 year model truck while the rest of the engine and accessories are a 1992. I've not had time yet to check out my friends 99 year model truck to see if the OEM fan would work on my truck. I need the revised shroud due to the thicker radiator. I think a 20" primary radiator fan might work on my truck. I'll verify this at at some point in the future.

I agree here.... you are very limited in the room you have on these trucks between the grill and the A/C condensor.

I have the HD GM fan clutch. I'm not sure if any other fan clutch will work any better, because I'm satistifed that the current one works rather well.. its just the cooling ability at long idles or very low rpms like you seen off-road sometimes, in high ambient heat / humidity.

Thanks for your comments.
Elbert

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I'm not going to run a "flex fan" because they make to much noise and I'm of the opinion that they also perfrom poorly at low engine rpm. --------------------------------------------------------------- Elbert, It is my opinion, that a Flex-a-lite Fan without Clutch will draw more air, and give you better cooling than any standard style OEM Clutch driven fan, and will even draw more air than the Clutch operated Flex-a-lite.
I had installed this set up I mention on a Firebird Trans Am I once had, as I was experiencing similar problems to yours. When I got stuck in summer rush hour traffic, my temps climbed through the roof, and the engine would begin to stumble, and run horribly.
The increased sound levels which you state didn't seem to be an issue for me. In fact, I thought my engine sounded a bit nicer after this mod. Best of luck, Mark
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Mark D wrote:

    A Flex Fan is fixed (clutchless), and stays at engine RPM. A Viscouis Clutch Cooling Fan turns slower when at ambient temps (70 +/-) then it does when under hood temps reach 160. The spring on the clutch unit is RPM range specific. Up to a cirtiant RPM the fan is at full pulley/water pump speed. After X RPM it will start slowing down. At Redline, it will be at roughly 1/5th the pulley/waterpump speed.
    This keeps the fan from wanting to desintigrate, helps keep the vehical in the proper tempiture range, and does not use any extra horse power. For that matter it takes less power to spin a warmed viscouis clutch at 8,000 RPM's then it would a flex fan if it would live that long.
    As for your "firebird trans am", it's one or the other,, not both. If it really had such over heatinbg issues it had cooling system problems.
Charles
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On Sun, 03 Jul 2005 11:01:55 GMT, Charles Bendig

Yes,
I don't see any gain in the cooling ability of a flex fan compared to a clutch fan at idle or very low engine rpms. The do make flex fans for various engine rpm ranges. I don't think on a stock GM pickup I'll have any issue with anything over 5,000 RPM.
I may be able to go up to a 20" radiator fan...this might help idle and low speed cooling. I'll check that out once I have the time and also and I can look at my friends 99 K1500. Sinnce I had to buy a fand shroud off a 99 year model truck so that my larger radiator would work.
Elbert
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On Sat, 2 Jul 2005 21:37:42 -0600, snipped-for-privacy@webtv.net (Mark D) wrote:

I too had a flex fan for a short time on a 78 z/28. It sure cooled good when the engine was over approx 1,500 RPM or so (been a long time ago). I saw no advantage at idle. The flex fan works good when properly setup. Still I think a clutch fan setup is the best for your primary cooling.
I'm going to make sure I have the correct fan diameter since I have a shroud off a 99 year model on my 1992.
I just don't like the flex fans, even if they work well at rpm.
Thanks for your comments.
Elbert
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Elbert, well, there are two things you could do to keep your engine running cooler at slow speeds. One, change the Thermostat to a cooller one (160) for summer. Naturally, when winter rolls around, you won't be getting much heat in the Passenger Compartment.
The other option, is to eliminate the clutch fan all together, and go with a Flexilite Fan, with Aluminum Spacer to replace the clutch. The fan will be directly driven at all times, and you will run much cooler under extreme conditions, and when at a standstill. Most speed shops sell these. These vary in pitch with increasing RPM's pulling much more air at low RPM's than a stock fan.
One last thing to check, and it's a good tip. If you have A/C, and live where there are those nasty Cottonwood Trees, pop the top of your Radiator Shroud off (Usually just a few Bolts), and look down in between your radiator, and A/C Condenser. Sometimes, that nasty fuzz accumilates like a blanket insulation in between these components, and causes poor heat transfer, and air flow.
Also, check that your radiator is not clogged in any way. Hope this helps. mark
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Mark D wrote:

    Never install a 160 degree thermostat in a modern fuel injected engine with out calibrating the ECM!
    If you street drive a fuel injected GM do not go +/- 10 degrees from the factory thermostat rating. The execptions are 93 up LT1 F-cars & Corvettes. Charles
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On Sat, 2 Jul 2005 21:27:33 -0600, snipped-for-privacy@webtv.net (Mark D) wrote:

I have a 180F thermostat and thats about the lowest i would go on this particular ECM controlled engine. I've never had a problem with the truck running, but I'm aware that if you run much cooler it screws with the ECM on this model truck.

Yes , I aware of the various flex fans. I don't think they do any better job at idle or very low engine speed.

radiator is new and I don't have any blockage on the radiator or condensor.
I think I need to verify the proper fan size for a 99 year model truck to match the fan shroud I have. There may be a subtle difference. I do know that the 99 year model truck has a large multi-bladed fan (12 fan blades approx) which resembles the fax style of the japense pickups. and appears to cool rather well.
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Elbert Clarke
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