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  1. #1

    Default Allison Problems

    So I just bought my first turbo diesel. A 2001 4x4 Duramax with the allison behind it. I bought it for a super cheap price because the trans is makig some noises.

    When driving slow speeds in 1st, 2nd, or reverse, it makes a whirring noise or some kind of gear noise. Kinda like when you put old transfercases in low and drove them fast... And now that summer is starting to heat up I've problems with it throwing the P0700 code. When driving at highway speeds the trans finally heats up past 170 and as soon as I slow down the service engine light comes on. I have a edge gauge, gauge not chip, no modifications to the computers programming. So I'd clear it out and try driving it, it continued to get hotter working its way up to 205 at which time the light came on again, so I pulled over and let it cool down to 145 cleared the codes and went on my merry way with the temps staying 167 and below. When the service engine light came on it put the truck into a kind of "limp" mode. Where is wouldn't shift above 3rd. After the cool down and cleaering the code the trans shifted fine all the way up into 5th.

    I just took the truck to a AAMCO store and had a complete trans flush with both filters and it did the same thing on the way home.

    The truck is always doing this a ways away from home so I can't limp it in with the light on. My gm dealership said that they can't read anything from the tcm if the code was cleared.

    I'm at a loss of what to do!!! Thanks in advance!



    I forgot to add that the dealership put a brand new transfercase in it for the previous owner.

    My friend and I went for another drive tonight and he was monitoring my gauges. First off the service engine light kicks on when the trans is at 185. When "limp" mode is activated the truck is stuck in fourth accordng to the gauge. We stopped to let it cool off so we could reset the service engine light and get to operate normally, Because we were bored we checked the cooler and it is ice cold, no warm fluid running through it. Still haven't been able to get it into someplace to get the codes read but something is definately not right.

  2. #2

    Default

    sounds to me like fluid isnt getting to the trans cooler. maybe flushing the transmission plugged the lines to the cooler? trans flushs are kind of a no-no. its a better idea to drop the pan and swap the fluid that way, keeps the stuff in the bottom of the pan from getting sent thru all those tiny trans lines.

    Alex


    2011 GMC Sierra SLE 5.3 Z71 4X4 Stealth Gray Metallic / 2004 Chevy Impala LS 3.8 Cappuccino

    Tow mirrors - Diablew Tuned - Flowmaster Regular 40 - Ready Lift 2.5' lift - BFG LT A/T K/Os - Carr Light Wing - TruckLite LED lights - Optima Red Top - 50% Front Window Tint - Line-X bedliner - Airaid MIT - Tekonsha P2 - ARS Billet Grill - Fia custom fit seat covers

  3. #3

    Default

    Quote Originally Posted by Sierraowner5.3 View Post
    sounds to me like fluid isnt getting to the trans cooler. maybe flushing the transmission plugged the lines to the cooler? trans flushs are kind of a no-no. its a better idea to drop the pan and swap the fluid that way, keeps the stuff in the bottom of the pan from getting sent thru all those tiny trans lines.

    Alex
    The trans lines on a duramax are 1/2" lines pretty big... but it was doing this before the flush. Also the allison holds 22 quarts a pan drop only gets you 13 quarts, so you have 10 containated quarts still trolling in your tranny. Aamco did a full service which is the external spin on and the internal filters, they dropped the pan and did the internal filter first and then flushed the tranny lines with the cleaning chemical.I'm wonderng if the trans has an internal thermstat or solenoid that controls the flow to the cooler and its messed up and stays closed for some reason....

  4. #4

    Default

    When i had my 2001 duramax i replaced 3 allisons in it within 10k of each other...

    2009 Chevrolet Silverado 1500 LT Z71 Crew Cab "All-Star Edition"

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  5. #5

    Default Another update

    So today after I got done driving it. The trans had a max temp of 154 and the cooler is luke warm, definately not 154 degrees but it does has a temp compared to last night. I'm going to crack the lines individually and seen if the truck pushes fluid through them.

  6. #6
    Sr. Mechanic ChevyHD's Avatar
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    Default

    Ya, trans flushes are not the way to go. I definitely wouldn't continue to limp your trans. And if there is any sort of thermostat, it would probably be best to replace it. The previous owner may have had a programmer on it and limped the trans causing the C4 and C5 clutches to burn up. And what did you do to read the code? Because the 700 just tells the ecm somethings wrong and to turn on the light.
    Last edited by ChevyHD; 06-03-2012 at 08:28 PM.
    Adam
    2004.5 CCSB Duramax
    Max Effort Tuning by Idaho Rob - Goerend Transmission - PCV ReRoute - EGR Blocked - Plugged Resonator - 5" Diamond Eye Turbo Back - Tie Rod Sleeves - All On Mod - Edge Insight CTS - Recon Taillights, Cab Lights, & 3rd Brake Light

  7. #7

    Default

    The previous owner towed a lot on stock settings, that's it. she pulled her big gooseneck horse trailer around to rodeo's.

    I have a edge gauge that just allows me to see the codes, it won't show me any further than p0700 tcm requesting mil It's not a programmer). It threw the code again finally while i was helping someone move tonight, so we are going to borrow a trailer and haul it to gm and have my buddy read the code when he isn't on the clock!

  8. #8
    Sr. Mechanic ChevyHD's Avatar
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    Default

    Well that's good then! Let us know what it turns out to be!

  9. #9

    Default

    So I got it up to the Gm dealer and my buddy tested it and it came back with a P1721 trim solenoid b controlled clutch engaged. And with some talking with some allison tech's they think that the o-rings on the solenoids may have been burned by an extreme overheat by the previous driver. I'm open for any suggestions on what other people think is the problem.

  10. #10
    Sr. Mechanic ChevyHD's Avatar
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    Default

    P1721 ( P0776 ) is a tie up; two gears at once for a split second. That can be caused by a speed sensor, transfer case problem, or a oncoming clutchpack overpowering an off going clutch ( bad news ). Bad tuning can cause this also. --Coming from Mike L. Allison Guru

    I would thouroughly examine all your solenoids, remove them and blow some air in the cylinder. Check your seals and o-rings obviously.

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