Question about 2001 Chevrolet Silverado 2500HD

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Clanking noise coming from Allison Transmission on a 2001 Chrevrolet Silverado 8.1 Liter engine

After starting my 2001 Chevrolet Silverado 2500 HD with Allison transmission 8.1 liter engine, I get a clanking noise that goes away after 7 to 10 minutes warming it in driveway. I can only describe the noise which sounds like a fan touching on something as it turns. It goes into drive ok & seems to shift just fine while driving the truck. Seems to only make the noise when it is cold. I recently (6 months ago) had the transmission serviced where the pan was dropped & fluid replaced. The truck only has 49,500 miles on it & is not driven very often. In fact is parked most of the time as you can see by the low mileage. Truck drives great on more noise can be heard & shift just fine. Can be reached at regular e-mail.......Thank You

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  • David Gallegos Dec 30, 2012

    Thank you I will give this a try. After getting under truck sounds like the noise is coming directly from the metal case of the transmission. I will try what you recommended & see if there is any change. Do think I should go back to the transmission shop I took it to for the transmission service.... rather than the dealer? I located the paperwork & this service was warrantied for 90 days or 4000 miles. I am hoping it is not anything serious. Dont know a great deal about transmissions let alone the Allison. I figured that a place that specializes in transmissions only would be better than taking it to dealer where their mechanics are not necessarily transmission specialists. Thanks again for your advice!!

  • stephen peirce Dec 30, 2012

    sometimes going to a trani shop is worse,because they do something to get you back in to spend more money their are alot of creeps out there dave lets hope that you can find it,but it sounds awfully like thats what happened,good luck

  • David Gallegos Dec 30, 2012

    Thank you!



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This does sound like theres a loose line tapping the engine/frame,during warm up the engine idles faster which could make it vibrate faster causing the the clanking or tapping noise,if this has started after trans fluid change,then check the lines running from the trani to radiator sometimes the service person might bang into something causing plastic clips that hold the lines to break,try getting under it and have someone start the truck and listen to see where it's coming from also hold the lines & see if the noise stops,the service guy could have unbolted something & never put the bolt back causing the clank ex.line may have a clip holding it thats bolted to the trani pan ?good luck

Posted on Dec 29, 2012


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SOURCE: I have a 2001 Chevy Silverado 4X4 Crew cab. 8.1

yes the front sensor will collect metal shavings causing this same problem.however you need to have it scanned when the lights are on. auto zone scans for free. the front sensors are in the front hubs. replace as a set as assymblies.

Posted on Dec 30, 2009

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SOURCE: I have a 2002 Chevrolet Silverado 2500HD with the

Hello. try a couple of things. make sure the rad is clean from any road debris or dirt. in fact, take a garen hose and pressure wash the rad and condensor fins real well. also miaght have both of the trans filters replaced. there is one inside the trans pan, and one spin on trans filter.

Posted on Jun 19, 2010

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2001 chevy 2500 hd 4x2 allison trans seems to loose pressure after coming to a stop, have to rev engine for a few seconds before it pulls again, whats up with that? 88800 miles

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by changing both trans filters and fluid, makesure you put dex VI in trans then if still having problems take to someone with a Tech 2 scanner and have them reset the trans adapts and try that, what it does is resets trans to factory (new) mode and then as you drive the truck it will adjust to your driving habits and shift points, but loosing pressure makes me think one of your filters is partially plugged...there is a spin on cartridge and the internal one in pan, change em both..good luck

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I get a clunking noise from the front of my truck when I cold start it and only for a few min as is warms up then it goes away. This started in cold weather 35-60F. I have a chevy silverado 2001 1500...

this engine has forged pistons whitch expand more than hyper-u-tec-tic pistons when heated . this is normal for this engine . my brother has a chevy silverado 2001 1500 4.8Lwith 650,000 kms and he said his made that noise when it was brand new and the dealer said this is normal. the truck still runs like new with lots of power and it still makes that noise before it reaches operating temp then goes away.My brother uses lucas oil treatment and it helps quiet the knock a little when cold.

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I have a 2001 Chevy Silverado 4X4 Crew cab. 8.1 liter, Allison Auto transmission My anti lock brake and e-brake warning lights come on after I drive for a few miles, they will not go off until I turn off...

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Pto on 2500 4 wd

Maybe aftermarket, but unlikely especially if it's not a current HD model. I've seen it on a 2001 2500HD but very rare. It has dash mounted controls. It would probably have to have an allison transmission. Just below, where the transmission rear output shaft comes out, there will be an attached pump with High Pressure lines coming out of it. If there is a cover plate there instead it might mean it's capable of having one but this is one of those questions like "If you have to ask, you probably don't have it"

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