Transmission Roar - Chevy and GMC Duramax Diesel Forum
Transmission Shop Discuss the Allison OEM, aftermarket, and the ZF-6.

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post #1 of 3 (permalink) Old 05-09-2012, 05:55 PM Thread Starter
Join Date: May 2012
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Transmission Roar

I have an 06' GMC Duramax Diesel LBZ with 6 spd. Allison transmission. It makes a roaring noise when the truck has been warmed up and being driven. It sound like mud tires but that is not the problem. It started doing this the warmer it got outside. Checked the fluid levels and that check out ok. It almost feels like it is not going into overdrive. When I slow down and it downshifts the noise is still there. What do you think the problem is. Thanks
paulpsch is offline  
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post #2 of 3 (permalink) Old 05-10-2012, 06:51 AM
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Check your fan clutch.
Mike L. is offline  
post #3 of 3 (permalink) Old 05-10-2012, 08:59 AM
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Like Mike L says, When I first got my LMM The fan kicked in and it was "holy shit" what is that as it roared. YUP, just the fan kicking in. Mine does it sometimes when I first start up and on long pulls up the mountains.

2008 LMM 1 ton drw crew 4x4. Iron Bull front bumper w/12,000 mile marker wench, PIAA lights, mag hy-tech trans and rear deff pans, 285s w/ rear spacers, fass fuel pump, XX performance duel filters, Banks air intake, AFE bladerunner intake manifold and turbo downpipe, PCV re-route, Supersteer tierods, leveling kit, 58gal transflow replacement tank, firestone air bags.
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