Results 1 to 20 of 22

Thread: '07 LBZ Air Intake Roar

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. 04-25-2007, 18:51 #1
    BradL07
    BradL07 is offline Enthusiast
    Join Date
    Apr 2007
    Posts
    16

    Default '07 LBZ Air Intake Roar

    Greetings to All:

    I am a new owner of an '07 Chevy Classic 2500HD with LBZ, having graduated from an '01 Chevy 2500HD with LB7.

    Comparing the LBZ to the LB7, I am noticing a lot more turbo whine with the LBZ, which I attribute to the improved air box on the LBZ.

    But I'm also noticing, sporadically, on a "cold" start, an intermittent "roar" under the hood with the LBZ - like the air intake is choked off and the engine is trying to suck a large amount of air thru a small opening.

    I've checked thoroughly for any foreign objects, etc. and only noticed the baffle at the passenger fenderwell, near the bumper, was loose in the fenderwell, and that's since been secured by the dealer in its proper location via caulking.

    But sometimes I still get this "roar" when taking off, after the truck has set overnite or at the parking lot during the day. Normally, all I ever hear is the turbo whine. Otherwise, the LBZ is so much quieter than the LB7.

    Anybody have any idea what this periodic "roar" may be attributed to? Anything to worry about?

    BradL07
    Reply With Quote Reply With Quote
  2. 04-25-2007, 19:27 #2
    Duramaster's Avatar
    Duramaster
    Duramaster is offline GMC World Class Technician
    Join Date
    Mar 2007
    Location
    Pacific Northwest
    Posts
    740

    Default

    One major difference from your old DMAX is the cooling fan. I had to change a belt on a 2007 Sierra classic yesterday, What a pain!!! The improved cooling system moves alot more air!!!
    Reply With Quote Reply With Quote
  3. 04-26-2007, 11:55 #3
    BradL07
    BradL07 is offline Enthusiast
    Join Date
    Apr 2007
    Posts
    16

    Default

    Good point Duramaster. I had the same thought but discounted it since the "roar" seemd to occur at "cold" start, if you can have such a thing in Houston.

    I assume the cooling fan has to be thermostat activated? So perhaps I may have an electrical glitch there.

    BradL07
    Reply With Quote Reply With Quote
  4. 04-26-2007, 12:36 #4
    JohnC's Avatar
    JohnC
    JohnC is offline Proud Deplorable
    Join Date
    Jan 2001
    Location
    New Hampshire - Live Free or Die
    Posts
    6,058

    Default

    It's a thermostatically activated fluid clutch. When the truck sits the fluid puddles up and locks the clutch. After a minute or two of running at road speeds the fluid redistributes itself and it unlocks.
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510
    Reply With Quote Reply With Quote
  5. 04-26-2007, 13:38 #5
    BradL07
    BradL07 is offline Enthusiast
    Join Date
    Apr 2007
    Posts
    16

    Default

    Aha....thank you John C, I believe that explains my situation exactly. As you describe, after driving a few miles, the "roar" would be gone. Hard to believe the cooling fan can be that loud at lower speeds, but it definitely is!
    Reply With Quote Reply With Quote
  6. 04-26-2007, 14:07 #6
    DieselMonk
    DieselMonk is offline Enthusiast
    Join Date
    Jan 2007
    Posts
    115

    Default

    have the same thing with mine. I wish there would be a fix for that.
    07 Chevrolet Classic, CC, regular box, Duramax Diesel, Magnaflow dual exhaust and Superchips tuned.
    Reply With Quote Reply With Quote
  7. 05-23-2007, 18:44 #7
    killerbee's Avatar
    killerbee
    killerbee is offline Bug Juicer
    Join Date
    Mar 2006
    Location
    Phoenix, AZ
    Posts
    144

    Default

    Quote Originally Posted by BradL07
    .

    Comparing the LBZ to the LB7, I am noticing a lot more turbo whine with the LBZ, which I attribute to the improved air box on the LBZ.
    The variable vane turbo in the new truck sounds more like a small jet than the older style wastegated IHI.
    Michael 04.5 SRW LLY

    custom stock intake, upsized boost tubes, Pre-turbo WMI, EFILive custom tune, Aerotech Scan Gauges.

    Go Smokeless!
    Reply With Quote Reply With Quote
  8. 05-27-2007, 07:48 #8
    Destroyer's Avatar
    Destroyer
    Destroyer is offline Enthusiast
    Join Date
    Dec 2006
    Posts
    23

    Default Same exact problem.........

    I had this happen to me I pulled over one morning and checked it out. I opened the Hood and a 750 lbs Tiger jumped out and took down a neighbor kid on the way to school. I guess it crawled up there to get warm. What a way to start your day.

    Seriously, I had this issue with my 454 Sub when it was hot. I am glad I saw it here as I plan to move to Alaska and I will have this most days now I won,t freak out and take the Casull to it. http://www.fishandhunttexas.com/454casull.htm

    I did the Banks Monster Exhaust, Banks Intake and Super chip programmer. I noticed the Beast is very quite now.
    Red(Red makes it go faster)2007 2500 HD LBZ
    Banks Monster Exhaust, Banks Cold air intake, Super Chip tuner.
    Banks Sticker 50 extra hp and 60 FT.lbs torque from a sticker awesome.
    500 HP and 780 Ftlbs torque.
    1984 CUCV Chevy Blazer 6.5l Retired Army truck
    awesome in its own way.
    Reply With Quote Reply With Quote
  9. 05-31-2007, 11:32 #9
    Destroyer's Avatar
    Destroyer
    Destroyer is offline Enthusiast
    Join Date
    Dec 2006
    Posts
    23

    Default I found this

    I think this explains it all very well.
    http://www.innerauto.com/Automotive_...em/Fan_Clutch/


    I guess if things a out of whack then what is happening is the fan is spinning up at full speed. It reduces HP and Torque which is why sometimes it feels as if the car in running over Moleasses. In a sense you car ,truck or what have you is trying to be an Airplane with out wings due to the fan trying to do 3000 rpms as opposed to spinning just fast enough to do its job. I wonder who thinks this stuff up they must be just as strange as me. I saw a truck once it had 350 Chevy it had three electric fans and an electric water pump. I was shocked to see no fan mounted on the engine.

    Hope you all enjoyed the link.
    Red(Red makes it go faster)2007 2500 HD LBZ
    Banks Monster Exhaust, Banks Cold air intake, Super Chip tuner.
    Banks Sticker 50 extra hp and 60 FT.lbs torque from a sticker awesome.
    500 HP and 780 Ftlbs torque.
    1984 CUCV Chevy Blazer 6.5l Retired Army truck
    awesome in its own way.
    Reply With Quote Reply With Quote
  10. 06-02-2007, 18:39 #10
    BradL07
    BradL07 is offline Enthusiast
    Join Date
    Apr 2007
    Posts
    16

    Default

    Now that I understand what is happening, I'm not as worried. But still, hate to hear that "roar" a couple times a week after a "cold" start.
    2007 Chevy Classic 2500HD CC SB LBZ Allison 4WD
    Reply With Quote Reply With Quote
  11. 06-19-2007, 08:14 #11
    Axle
    Axle is offline Newbie
    Join Date
    May 2007
    Location
    Lake Powell
    Posts
    7

    Default

    My new 2007 Silverado Classic also has this intermittent fan roar. It only seems to happen when the truck has not been run for a day or two. Then it happens upon first start.

    The roar is amazingly loud even at low speeds. Would anyone here consider this a warranty issue? Or would the replacement fan clutch do the same thing?

    Seems like the consensus here so far is that nothing is really wrong but that the design has a short-term, annoying loud noise.
    Reply With Quote Reply With Quote
« Previous Thread | Next 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
  •  

Forum Rules