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12-20-2011, 05:17 PM #1
Difference between a 1996 Chevy 1500 Z71 5.7 and a 97
So, I have posted a few posts trying to figure out my extremely loud fan. The reason it interested me so much is because in my yard, we have my 1996 z71, two 98 k1500 4x4's and a 97 z71. My fan on the 1996 is a five fin fan whereas the others are comprised of 11 fin fan blades i believe. When i hammer the gas, the fan makes an aggressive roar, theirs has none. Inside their trucks it is completely silent except for their exhaust. We all have basically the same semi-illegal set up for exhausts, true duals, two cats and straight pipes no mufflers. They say that mine is the loudest from behind, but my unrelentless motor/fan noise inside of my truck while driving deprives me of the privelages of hearing hippies die when i give my pipes a yelp. In my research, i have found that one of the improvements to the 97 model was making the fan less noisey
(For '97, Chevy has not changed their line significantly, but has added a few noteworthy items. For one, a passenger-side air bag with key-operated deactivation is offered with the latter likely becoming standard as a result of recent fatal accidents to children and small-statured adults. Also new is an improved HVAC system, tighter turning radius for 4WD models, a more responsive electronically controlled variable assist power steering, improved automatic and manual transmissions," a quieter and more efficient cooling fan", three new exterior colors and a natural gas-powered 5.7-liter V-8 engine. ) -------http://www.theautochannel.com/vehicles/new/reviews/1997/nhromiak09019702.html
I would love to be able to enjoy the sound of my exhaust without the sound of the loud roaring/ 1st 5700 series vortec. Besides installing a 1997 motor into my 1996 body, is there anything else that I can do? I thought of putting in a fan from a 97, 11 plastic fins instead of my 5 steel fins, but I am not sure of the internal components that are combined to create a more efficient fan. What do you guys think?
P.S. my truck is completely stock, brand new tensioner, idler pulley and belt, 109,000 miles no motor work done at all, absolutely stock with regular maintenance... Have at it!If you can't beat em', Scare em'
Blue 1996 Chevy 1500 z71 5.7 straight pipes
12-20-2011, 06:43 PM #2
swap fans ... should be same wiring ect.
12-20-2011, 09:56 PM #3
12-21-2011, 12:33 AM #4
fan roaring all the time is a symptom of a bad fan clutch, it should only roar when cold for a minute or so until the fluid warms up and then only roar again when the fan clutch goes into full lock when the spring on the front of it gets too hot from reaching the overheating point.
you sure its 11 blade? it should be 9 blade just like the later diesels got.
Last edited by outalne94z71; 12-21-2011 at 12:36 AM.my 88 sas "mudwasp"
88 chevy k2500, started as reg cab lb, now reg cab shortbox, sas 17'' of lift, 52'' front springs f.i. bbc , 79 dana hp 60 chevy outers, 14bolt ff spooled divorced 205 and cut 40'' gumbos
1998 k3500 gmc crew cab dually L65 6.5TD 4l80e with a couple of mods
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12-21-2011, 08:58 AM #5
I thought it was the clutch, i replaced it about 6 months ago, it was froze up so it made sense that it was loud, mine is brand new now and moves as smoothly by hand as the 98 does. I was told i could have gotten a bad clutch, how do i tell?
12-21-2011, 05:10 PM #6
Well, I took it back to the shop I had the fan clutch put in at and just asked him his input. He seemed baffled and took three other fan clutches, the first two seemed ****ty as well, put the third one on and took a few dings out of my fan blade, I'm not sure if it was the combination of the clutch and fan blades being bent or just the clutch, but for the first time since I have had my truck, I can hear my exhaust. Best part about it, the shop charged me absolutely nothing for 3 hours worth of tinkering around. Great bunch of guys!
12-22-2011, 08:39 PM #7
If you use the cheap fan clutches they tend to not work very well, my 94 has the same bi metal fan clutch, the metal grips the shaft on the water pump pully harder when the metal heats up, it expands and grabs...Simple enough design, but if the bi metal is cheap, it will usually stay locked down.
The 11 fin fan was prolly a flex lite style fan, they still have a fan clutch on them, but the extra fins and being made of plastic makes them quieter, since they don't have to spin as fast.1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
Original engine and tranny
wrecked twice stolen once
Diamond Plate bed rails
Original Alloy wheels
Original fancy smancy cup holder
Original plastic bed liner
K&N Cone Air Intake
Dual MagnaFlow exhaust(not true dual) with chrome tips
MSD Street Fire Performance Ignition coil
12-23-2011, 02:39 PM #8
fan clutches are thermal viscus fluid clutches that have a bi-metal spring on the front of the housing that when they get hot enough turn a shaft on the front to divert the fluid to almost completely lock the input shaft with the hub. the non thermal clutches just use silicone fluid in them and work by the strain of flowing the silicone
12-23-2011, 09:31 PM #9
The bi metal fan clutches Chevy uses do not have fluid in them, I doubt Chevy has ever used a vicious fan clutch, that's more of a Toyota/Honda/Nissan thing. Its not metal on metal, it's more like a clutch type material making the contact. I should of been more clear.
12-23-2011, 10:33 PM #10
The 97 fan if I recall is a screw on fan where the 96 is a bolt on fan but changing the fan blade itself will work if the bolt pattern is the same on the clutch itself Sounds more like your fan has been warped or damaged when it was worked on maybe? Be sure to check the bolts that hold the fan to the clutch.94 Chevy ext. cab dropped on Bell Tech 2/4, Custom paint, Built 350, Custom interior, Cowl hood, Custom sound, AKA Big Red
96 Chevy Suburban 2500 Diesel Custom built 6.5 turbo diesel F code HO (sold)
99 GMC Yukon
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