GM Truck Club
THE PREMIER CHEVY TRUCK & SUV FORUM
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 9 of 9
  1. #1

    Default 1996 5.7 high rpm squeal

    My 96 Z71 Silverado 1500 has an extremely loud fan and sqeak. I noticed when I got it that the clutch on the fan was actually froze up, so I have replaced the fan clutch, belt, idler pulley and alternator within the last couple months all in searching where this squeak is coming from. When I hammer on it, it sounds good up until about 4500 rpms right before its shifting then it lets out a terrible squeal and the fan is so loud i can barely hear my straight true duals over it. Any idea why A) the fan is so damn loud, or B) the high pitch squeal has not left with the different replacement parts? Thanks.
    If you can't beat em', Scare em'
    Blue 1996 Chevy 1500 z71 5.7 straight pipes

  2. #2
    Sr. Mechanic Ethan's Avatar
    Join Date
    Sep 2009
    Location
    Cedar Park, TX
    Posts
    150

    Default

    4500 RPM's is red line for that truck, if it's the 350, they are not meant for high rpms. So, what you're experiencing(if you're actually that abusive to your truck) is prolly normal operation. When you redline a low RPM engine, they tend to not like it.

    The roaring is prolly just the fan, at 4500 rpm, that fan is gonna spin almost as fast as the crank is, so it's gonna roar.
    1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
    160,000+ miles
    Original paint
    Original interior
    Original engine and tranny
    wrecked twice stolen once
    Diamond Plate bed rails
    Power windows
    Original Alloy wheels
    Original fancy smancy cup holder
    Tow package
    Original plastic bed liner
    K&N Cone Air Intake
    Dual MagnaFlow exhaust(not true dual) with chrome tips
    MSD Street Fire Performance Ignition coil

  3. #3
    Legend
    stephan's Avatar
    Join Date
    Sep 2010
    Location
    Far West, Oregon USA,
    Posts
    8,606
    Blog Entries
    1

    Default

    Does this squeel only happen with the AC on @ the higher RPMs? If so it could still be the belt or the AC clutch itself. Put everything in heat position (not defrost) & try it.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  4. #4

    Default

    Thanks for the input, I guess I made it sound like I am beating my truck. That I am not, but when I pull out to pass, hammer the throttle, before it shifts when it is getting up in high RPMS it lets out a loud squeal, that's what I was getting at.
    If you can't beat em', Scare em'
    Blue 1996 Chevy 1500 z71 5.7 straight pipes

  5. #5
    Legend
    stephan's Avatar
    Join Date
    Sep 2010
    Location
    Far West, Oregon USA,
    Posts
    8,606
    Blog Entries
    1

    Default

    No worries RB, 4500 rpms isn't beating it. The 5.7 is good to 5800 with stock valve springs. Did you try it with the AC off? Do you still get the squeal?
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  6. #6
    Sr. Mechanic Ethan's Avatar
    Join Date
    Sep 2009
    Location
    Cedar Park, TX
    Posts
    150

    Default

    ^ Is it really? Cause my 94 350 red lines at 4500 rpm, and has a max of 5000 rpm, according to the manual, and the scan tool.

    It might be some belt sequel. But since you've replaced parts idk. I know there is a TSB on the belt tensioner pulley, saying to replace it with a slightly smaller one.
    1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
    160,000+ miles
    Original paint
    Original interior
    Original engine and tranny
    wrecked twice stolen once
    Diamond Plate bed rails
    Power windows
    Original Alloy wheels
    Original fancy smancy cup holder
    Tow package
    Original plastic bed liner
    K&N Cone Air Intake
    Dual MagnaFlow exhaust(not true dual) with chrome tips
    MSD Street Fire Performance Ignition coil

  7. #7
    Legend
    stephan's Avatar
    Join Date
    Sep 2010
    Location
    Far West, Oregon USA,
    Posts
    8,606
    Blog Entries
    1

    Default

    Quote Originally Posted by Ethan View Post
    ^ Is it really? Cause my 94 350 red lines at 4500 rpm, and has a max of 5000 rpm, according to the manual, and the scan tool.
    I don't know Ethan. If it says 4500 then I wouldn't go above it, but the weakest valve spring I'm aware of that GM made is good to 5800 before valve float. Maybe GM is trying to reduce the number of engines they have to warranty.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  8. #8
    Sr. Mechanic Ethan's Avatar
    Join Date
    Sep 2009
    Location
    Cedar Park, TX
    Posts
    150

    Default

    I guess they put a low rpm crank in mine, back when trucks were designed to be trucks, and not racing lol.
    1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
    160,000+ miles
    Original paint
    Original interior
    Original engine and tranny
    wrecked twice stolen once
    Diamond Plate bed rails
    Power windows
    Original Alloy wheels
    Original fancy smancy cup holder
    Tow package
    Original plastic bed liner
    K&N Cone Air Intake
    Dual MagnaFlow exhaust(not true dual) with chrome tips
    MSD Street Fire Performance Ignition coil

  9. #9

    Default

    I did try it with the ac off and all, i'm just lost in confusion i guess. Sounds kinda stupid but i'm wondering if my truck might have been programmed or chipped modestly because I have been watching a lot of videos and what not of 96 chevy's on youtube and it seems they are all shifting at right under 5k, mine actually has a little bit higher shift points... could higher shift points from a chip or programmer cause the fan to run so damn fast that it chirps at a slightly higher rpm??? when i say slightly higher, i mean like 5000-5100 somewhere in there. And by the way, i'm looking to do a little bit of modification, crank out a few more hp, i know the age old question for chevy truck guys is what are some cheap mods, but seriously haha what are some decent mods for under 1000? My first step is going to be getting a tune up, fix a couple small things that are bothering me (non-engine related) and then look at getting a little more power. Any help would be greatly appreciated, if your paying tax dollars, your paying for my upgrade lol. Thanks!
    If you can't beat em', Scare em'
    Blue 1996 Chevy 1500 z71 5.7 straight pipes

Similar Threads

  1. Belt Squeal
    By szn9rg in forum Chevy Silverado Forum (GMC Sierra)
    Replies: 29
    Last Post: 01-23-2012, 01:25 AM
  2. Squeal
    By Lee Indy in forum Lifted & Offroad Suspension
    Replies: 3
    Last Post: 04-23-2010, 03:30 PM
  3. 6.0 v8 Squeal help!!!
    By H2inMd in forum GM Powertrain
    Replies: 1
    Last Post: 05-13-2009, 10:12 AM
  4. High Pitched Squeal from 89 Sub Rear Axle
    By Big6ft6 in forum Chevy Suburban Forum (GMC Yukon XL)
    Replies: 4
    Last Post: 01-22-2009, 05:46 PM
  5. Squeal
    By chelsea in forum Chevy Colorado Forum (GMC Canyon)
    Replies: 1
    Last Post: 09-18-2006, 12:53 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •