Chevy Silverado/GMC Sierra's w 8100/Allison



  • gmcgtgmcgt Member Posts: 15

    Just yesterday 5/10, my Alli started making an unususal noise also. It happens while the trans is cold at around 10 mph as you described. As it turns out I hit 1600 mi yesterday also. After reading your message several weeks ago I began listening closely to mine. All was normal until the 1600 mi mark. Are you still experiencing the noise? Is anyone out there also experiencing this noise? If so has it been diagnosed by GM?
  • obyoneobyone Member Posts: 7,841
    what did I say about the Allison. Maybe it is true.
  • 1i2cu1i2cu Member Posts: 32
    Bargain price 2.16 a gallon. Most of the stations were asking 2.29. With all the refineries in SOCAL the gas should be cheaper. BOYCOTT TOURISM TO CALIFORNIA. 8.1 hauls with 92 octane. Will I sell it ? Over my dead body.
    Hey Tim, If you had a long bed, you could carry more cold long necks.

  • minikinminikin Member Posts: 389
    Well now, that's not hard! Who the hell would want to go there anyway? And before ya'll Califorians climb all over me about that, I've spent 20 years of my life someplace in that state, half of it on purpose, half of it not. Left at the end of '89 and will not ever live there again. (Premium gas in S.E. Denver metro is $1.91 today)
    -- Don
  • hdriderhdrider Member Posts: 49
    At the price of a Duramax, you could buy a whole lotta gas at the current gas prices!
  • mgdvhmanmgdvhman Member Posts: 4,157
    I don't know......what did ya say?

    - Tim
  • obyoneobyone Member Posts: 7,841
    that with the Allison, you couldn't hear the Duramax. Course the service advisor had to inform them that "this is normal".....
  • mgdvhmanmgdvhman Member Posts: 4,157
    ...that was it!

    - Tim
  • elderdog1elderdog1 Member Posts: 10
    8100/ al/3.73 now has 5000 miles last two tanks got 12.4 and 12.6 60% interstate the other 40% just driving , filled up today 1.55.9 in lexington ky, not to heavy foot unless one of them ole fords or dodges pull up next to me at a light , then its let em rip
  • sf0383sf0383 Member Posts: 204
    Filled up with 87 octane yesterday in Atlanta for 1.529. I actually saw it down the road from where I filled up at 1.39. Problem was, so did everybody else.
  • ryanbabryanbab Member Posts: 7,240

    Man maybe i need to move and get away from these $1.99 for 87 octane.
  • navy4navy4 Member Posts: 44
    The price of gas is another reason to get away from Chicago!
  • sf0383sf0383 Member Posts: 204
    Actually that was for 89 octane. The cheap stuff is $1.45
  • mgdvhmanmgdvhman Member Posts: 4,157
    ...know why it's called that?

    ...cuz it blows!


    - Tim
  • owenm2owenm2 Member Posts: 4
    My GMC 2500HD 4wd, ext cab/longbed 8.1 hit the port last week, and is supposed to be delivered today. Trying not to get my hopes up, as so many delivery dates have passed.
    Pretty sure it will be the first one in this country. Gas here on base is $1.19, was .77 last year! The Grand Cherokee that I've been driving for the last 6 years never got better than 10mpg, so this 8.1 won't shock me.
    Just noticed that the heated mirror option has just the driver mirror heated. Would think they would consider the other mirror as well!
    Will see tomorrow (hopefully) if it arrived in good shape, and as ordered.
  • mgdvhmanmgdvhman Member Posts: 4,157 2K 2500 LT has both mirrors sure about that?

    - Tim
  • owenm1owenm1 Member Posts: 29
    · Dual high-visibility extendable trailering mirrors

    · Electrochromic heated driver's mirror with power control

    · Tonneau cover (Wideside only)

    I cut this off the option list from the GMC site, my brochure says the same.................Owen
  • mgdvhmanmgdvhman Member Posts: 4,157
    ..camper mirrors......forgot about those

    get regular ones and both will be heated

    - Tim
  • quadrunner500quadrunner500 Member Posts: 2,721
    I've got the camping mirrors. Owen's got something new. No heat or electrochromic on mine. They are air conditioned however. Hot in the summer, cold in the winter!
  • eric2001eric2001 Member Posts: 482
    Too bad these weren't factory mirrors:

    Buy them here:

    I might have to get a set of these for my HD, if it ever arrives.

  • owenm2owenm2 Member Posts: 4
    The Chevy brochure says "heated mirrors", the GMC says "Electrochromic heated driver's mirror with power control". These are not the camper mirrors. Picking the truck up in a few hours, will post my first impressions soon.
  • mgdvhmanmgdvhman Member Posts: 4,157
    ..I don't know about HD's...but new style 'Rados with heated mirrors are both...

    Hd's better be the same!

    - Tim
  • n75v111n75v111 Member Posts: 243
    On Both Sides---

    Anyone have 8100HD SB 26 gal Fuel Tank schematic showing the fuel lines in & out they could FAX-(641-754-2731).

    Need to know which line to tee into for Aux. transfer (39.5 gal aft-axel).

    Thks - 75v
  • owenm1owenm1 Member Posts: 29
    This truck is awesome! Only complaint is the small tires. Looking at the Dunlop Radial Rover RV's in 255x85x16's, about 2 inches taller. Any comments on that size? Think they will mess up shift points/computer?
    Will be washing tomorrow, still has the shipping coating on it. Polo green looks great. Both mirrors have the little heat emblem, so hoping they both have heat.
    Anyone else have the snow-plow prep? Unable to verify that I have the option, other than the 130amp alternator.
    1040pm here in Korea, but I need to go down and look at my long awaited truck again!

    2001 8.1, 4wd longbed ext cab, Allison auto, 4:10 locking diff, trailering/HD/snow-plow/suspension, roof marker & fog lites, heated mirrors, rear defogger, electric shift xfer case, skid plates

  • quadrunner500quadrunner500 Member Posts: 2,721
    Those are 'the' perfect (oversize) tires for your rims, according to guys at the diesel page. The Dunlops are very popular according to customer feedback at the Tire Rack. 265/75 are same height, but slightly too wide for rim, edge folds under a bit, gets rounded at the corner.

    If you have the 130 amp alternator, you've got the snow plow prep. Sounds great!

    BTW, sounds like the standard factory heated mirrors. Are you sure they are extendable? Or just fold back on impact?
  • owenm1owenm1 Member Posts: 29
    I like "perfect"!
    Not extendable mirrors, did check, both have heat!! Anybody running 255/85R's???
    I want to sleep in this truck!!!!
  • owenm1owenm1 Member Posts: 29
    Well, I've driven the 8.1 for 86 miles, and the full 34 gallon tank is at the half mark, relating to a 5.05 mpg. Can it get any worse? 86/17gal=5.05mpg
    Truck does have some awsome power, but I'm hoping for the 11mpg averages I've been reading about.

  • mdirvinmdirvin Member Posts: 8
    I have 1700 miles on my 2500HD/8.1/ext cab/4.1 and usually I get between 170 and 200 miles on the first half tank. It has done that since the second tank. The first one was less, but it came "full" from the dealer, and it was not quite full. Usually I will fill up around the 1/2 tank mark, just so I have enough cash to pay for it. I have pulled my 5th wheel for a short distance (120 mi) I filled up before and after the pull, the millage was 7.9. We were bringing it home from the dealer and it was at dry weight approx. 12,000 #. If I drive just back and forth to work (5mi rural driving) then the millage stays at about 10.5. The engine just gets to temp by the time I get there, and the transmission never get warm. On the interstate with the cruise control set for 65 then 13.5 . Of course I live in northern ILL so its about as flat as you can get, however we do have some wind.
  • eric2001eric2001 Member Posts: 482
    With larger tires, I am also looking into the 255/85/16's. Did everyone get the spare done also? Does it still fit there with the larger tire? And did anyone trade the tires in when new? What kind of deals did you get? Thanks for any replies
  • ryanbabryanbab Member Posts: 7,240
    your not joking about the wind

    im from northwest indiana.

    i was on US30 a few wks back and was almost blown off. Also going down to lafayette down I65 i had to deal with 50-60 mph cross winds
  • mdirvinmdirvin Member Posts: 8
    I picked up my truck on a Friday. On Saturday I drove down to my daughters in St. Louis. The mil age down was nothing to brag about, but on the way home I got 14.75. At first I was elated, then I remembered there was a very strong tail wind coming home. Needless to say I have never seen that mil age since.
  • dinosierradinosierra Member Posts: 14
    Under the truck,running a cable for the CB ant. Has anyong noticed the size of the drive shaft. I measured 18 1/4" around.
  • sonjaabsonjaab Member Posts: 1,057
    Is your factory window sticker missing ?
    Look in you glove box for the factory code
    sticker . It should show VYU code on it
    somewhere. That means sno plow prep pack
    Also look under the hood on the pos
    battery cable it should have a red boot
    attached too it for power hook up also should
    have a big plug on the firewall covering up
    a added hole for plow controls to pass thru.
    On the dash next to the pass airbag cut off
    there should be a AUX LIGHT button with
    yellow indicator light. This is for roof
    mounted light. Ican't find the wires but they
    should be behind the plastic a piller cover
    or stuck up in the headliner somewhere..
    If you find them before i do please post here
    Thanks enjoy you new truck.........Geo
  • n75v111n75v111 Member Posts: 243
    Figured the Aux lite sw was for the Snoplow lites so expect the wiring plug to be up front somewhere?
    (Planing on using sw to operate eletric fuel pump to transfer fuel from Aux tank to main tank while on the move.)
    Checking with dealer on Tue for location-bet he won't know anything though.

    Manual tells about roof wiring if you want to add top emerg. lite etc.

    DON'T Anyone have the Shop Manual to show fuel lines, vent lines and fuel return lines schematic back to tank???

    mpg @ 3000 5o/5o town/hiwy iowa flat land mi on 8.1/3.73 4x4 SB prety steady at 10.5 - Sure is nice with the 5th wh though.

    BTW - You can Kill the DRL's with the dome Sw. then turn on Parking Sw and Fog lamps by them self.

  • sonjaabsonjaab Member Posts: 1,057
    There is extra wiring up in the nose behind
    the grille tucked up in the headlight buckets
    for plow lights..But they are rigged up to
    the headlights anyway. the switch is for roof
    mounted light . Yellow flasher light required
    in NY on roof. Wires must be somewhere up in
    the headliner or A pillar. Will call snow plow
    dealer today cuz GM dealer don't know.....Geo
  • kdubkdub Member Posts: 4
    Found some numbers on the diesel page for comparable crew cabs with Duramax... Any chance the 8.1 Gas with Allison would weigh any less? Better yet, has anyone got the scale weight for a LS or LT 2001HD Crew 8.1 4x4 Long Box? I'd like to plan payload with real numbers.

  • cowboyjohn1cowboyjohn1 Member Posts: 125
    Weight of a 2500HD, LT, 4X4, Long bed with a half tank of gas = 6280 pounds. Happy loading! Oh, don't forget the weight, balance, and CG..Opps, that is airplane talk.
  • kdubkdub Member Posts: 4
    Thanks CowboyJohn.. Not sure by your truck description if your rig was in fact a crew cab or not... can you please confirm one way or another?

  • nmkevinnmkevin Member Posts: 7
    Anyone successful in finding an after market tank for the short bed ? I am getting to know the gas girl pretty well, not sure that is a bad thing though !!
  • eric2001eric2001 Member Posts: 482
    Any of you with the 2500HD short box that went to larger tires: did you have any problems fitting a larger spare? Has anyone gone to the 255/85's and had the spare done also? Thanks.
  • cowboyjohn1cowboyjohn1 Member Posts: 125
    Sorry about the description. It is an extended cab. I was a little surprised about how much it weighed. I have an 88 F250 regular cab which weighs about 5800, so an additional 500#s surprised me. But the 8.1 pushes it around about as much as I want it to. Very happy with it.
  • owenm1owenm1 Member Posts: 29
    Well, MPG is improving slightly, 7.3 on that 24 gallons. Have we found anyone running 255/85's yet? I hate to have them shipped all the way over here (Korea) then find out they are too big. Earlier post said they are "perfect" according to guys on the diesel page. Would feel more comfortable if I saw a few posts here that said they were awesome. I want the Dunlop Radial Rover RV's.
    Also, any new info on Hypertech making a reprogrammer for the 8.1? (for taller tires)
    Truck does have the snowplow prep. Only got it to get the "HD torsion bars".
    Allison has one rough shift point when stepping into it. (explains my 7.3mpg right?) Actually, have been going easy on this beast 98% of the time.
    Changing oil on Saturday, anyone bought a Fram oil filter for the 8.1 yet? ##? Thanks.................Owen
  • mgdvhmanmgdvhman Member Posts: 4,157
    I'd buy some paper towel and a rubberband before I bought a fram filter!

    ...they have been rated the worst filter you can buy.

    Get a Mobil 1 or a Delco

    - Tim
  • ryanbabryanbab Member Posts: 7,240
    DO THE 8.1'S TAKE THE PF59?

    I think your better off using no filter over a fram
  • n75v111n75v111 Member Posts: 243
    Fram #8873-- only one I could find-
    Their not that bad!!.
    AC454 don't seam to be on open market yet??

    But Oh Boy!! Filter on left side rear above exhaust cross over and the 4wh drive shaft U-joint. Hot Oil DOWN YOUR ARM kinda deal!!

  • boatboy1boatboy1 Member Posts: 1
    hi guys i live in wa. state and am looking at the 2500hd8.1 w/ allison. lots of mountians!
    whats your bet on mpg?
  • kdubkdub Member Posts: 4
    Anyone know what the steel wheel load ratings are on the 2500HD versus the forged alumninum wheels...I'd like to maximize my payload safety and plan to buy 10 ply 3415 lbs max rated tires, but I'm not sure which wheel to order to take advantage of the extra tire capacity... someone on another forum thought the aluminum wheels were rated to 3200?

    any load ratings stamped on the rims?

    thanks guys
  • minikinminikin Member Posts: 389
    Fram -- What Tim said @ post 494!!!
    -- Don
  • jblair1jblair1 Member Posts: 5
    I'm hoping somebody can give me some advise on running boards for my '01 2500HD Crew Cab. I would get nurf bars but I need something practical to help my 5" nothin wife put my rugrat into the carseat. Hoping for something that can mount a little lower than a standard running board (4" instead of 2") and something a little wider (7" instead of 5"). Thinking black might go with my pewter truck. Again, probably look kind of crappy compared to nurf bars but in this case practicality rules. Any advice would be appreciated.

    Also, my truck was delivered with the trailer plug broken and the mouinting mangled. Dealer said it probably happened when it was taken off the auto hauler. Dealer said they'd pay to find some shop locally that can try and staighten it out and replace the plug with an aftermarket (cutting the wires and splicing a new one on). I figure they should be replacing it with a new hitch and I shouldn't have to settle for some hitch shop character with a cresent, hammer and old can of spraypaint trying to patch things up. Am I being unreasonable?

  • sf0383sf0383 Member Posts: 204
    I'd tell them that I paid for factory stuff and that's what I wanted but if they want to try to fix it locally fine but You will be the judge of whether or not it is acceptable and they need to be prepared to replace the hitch otherwise. Ask for that in writing and see what happens.

    IF you decide on nerf bars, I put the Westin CPS on my Crew Cab and they work good. Yard apes can climb in by themselves
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