Pardon if this has already been covered. Being new here, I haven't read all the earlier posts


My Chev. LLY/Allison is 3 weeks old, and sometimes the transmission is sometimes very noisy.....a loud whining, fan-like sound. It sounds like a well-muffled gas engine sitting in neutral, being revved. This happens every morning as it's warming up, going slow through maybe the first 3 gears. Also after highway cruising for awhile and coming to a stop then accelerating again, it's the same loud noise up to about 4th gear.....after that it's gone. The service department tells me that Allisons just make noise - not necessarily that they're supposed to, but sometimes they do and it's no cause to worry. Elevation 4200'-7000'. What's going on?


Also, on a slight downgrade doing about 2200rpm, I shifted into neutral and took my foot off the gas. The engine revved by itself to about 2500 before I put it back in D. It would also happen at 1500rpm. Elevation was 7,000'. What's this about?


Thanks.


***

The Ally is a noisey trans. It has huge gears. Some of the noise might not be the trans. Might be the turbo. When DieselTech got his new LLY and we traded trucks from time to time, I heard noises out of his that mine did not have. Turbo.


mike

I agree that the Ally is a noisy unit. It is a heavy duty trans and they are not usually installed in quiet vehicles.


I have a whine at low speed.......maybe at all speeds but I can hear it at low speeds.


it is a tough but quirky tranny, the computer gets pissed if you change driving styles or power levels, has the occasional flared shift or short stiff shift if you change conditions.


The ally has had virtually no problems if left at resaonable power levels.


Don't worry.

http://www.dieselplace.com/forum/smileys/Approve.gif

Does this link apply to the trans used in our GM trucks?





Do not allow the vehicle to coast in neutral (N). This can result in severe transmission damage. Also, no engine braking is available.







http://alliance-docs.freightliner.com/dynaweb/english/engfcccdm/rvdm/@Generic__BookTextView/1698;cs=default;ts=default





Rob

More than likely you are hearing the fan engaging. Mine does it on warm up for some reason.

MT.Hunter


What a coincidence...I've got new 04 CC LLY SLT 4X4, about 700 miles on it, and while I'm driving down the highway about 70 mph and 2300 rpm , alli is just smooth and quiet, then out of nowhere I get a loud noise coming from the under carriage. This noise sounds just like the tranny before locking up in 5th for cruise. Sounds like a fan almost, but where is the electric fan on the truck? I am at a loss as to why quiet one moment and whirling noise the next.


If I try to accelerate, the noise also intensifies...I don't notice any loss in power, although my experience with this equipment setup is limited so I don't feel I would know if such was happening...I am causiously concerned....fluid levels are correct for both cold and hot readings...truck made in January 04, could I be in need of software update.......This is driving me nuts....





MK

Sounds like fan clutch kicking the fan in and out. If so, this is normal, especially with the temps you might be seeing right now. Also, when engine is cold, the fluid in the cluth is thick, and the fan will work a bit then.

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Driving across the north Cascades my Allison was making horrible screaming noises.Happened twice and lasted 5-10 seconds.Was pulling 9500 lb.fifth at the time. Not the engine fan. Totally different sound. Tranny was not overly hot according to the gauge. This tranny doesn't have its own fan does it? I'm going to the dealer today but this is worrisome. Sounds like something is dying. Just after getting home my hydro boost crapped out totally. Every time I turned the wheel the brakes came on. Could that be related?


Any help greatly appreciated.


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Could be your power steering pump was dragging or stopping and your fan belt was screaming at you to stop.