# Truck Tranny Problems



## PinkyRingz (Nov 26, 2008)

2002 GMC Sierra 3500/Duramax Diesel/Allison Automatic Transmission/ 210,000 kilometres. 

Truck will slip out of gear. Put in drive and move ahead maybe fifty feet then the truck goes into the neutral and the gear indicator light blinks. Shift to any other gear and does the same. 
Let the truck run for a bit then it will shift hard and awful then go...seems to start in second gear then shifts up. 
Tranny fluid is a little low. No metal bits on the dipstick and doesnt smell burnt. 

Ideas?


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## danknight60 (Nov 7, 2006)

sounds like the start of a big problem i would bring it in to have it service before you brake some big it sounds like a gear is worn out so it might be an easy fix OK 

good luck bro


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## PinkyRingz (Nov 26, 2008)

........that sux.....and RIGHT after i get the plow on and working too....figures...lol


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## snow7899 (Jan 22, 2005)

I would bring it to a shop (or dealer) and have the codes read on the tranny computer. The flashing light is telling you there is a fault in the system. Sounds like the tranny is going into limp home mode.


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## SullivanSeptic (Nov 30, 2008)

*Question about new allison*

Hey guys, I have a 2007 2500hd NBS with the LMM Duramax. Does anyone know the proper maintinace schedule for the Allison. I am getting conflicting reports from my dealer and a couple of the guys in the shop.

I own a couple of diesels but never one with an Allison tranny


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## Spitz (Feb 28, 2008)

Gm has had trouble with the older range switches and such, some even have you install a shield to keep snow and water away from it.. Definatly nothing can be for certain on the internet, best take it into a shop who can see it..


Service- I usually flush any transmission at 50k or less no matter what the fluid looks like, then again i do my own so its not a big deal to me.. No idea what the recommended changes are though. ATF breaks down just like any fluid though, keep that in mind. The allision isnt much different from any other trans though, just larger with a little more software power behind it.


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## snow7899 (Jan 22, 2005)

On your 07 2500 duramax, the book suggests every 25K under the severe service. I recommend at least once a year, don't forget the transfer case, I do it at the same time.


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## no lead (Dec 10, 2008)

see why they need a bailout? GM=lost money


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## NICHOLS LANDSCA (Sep 15, 2007)

FYI 06' and newer Allisons require dextron VI


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## Livingreen (Nov 12, 2004)

did you figure out why it was slipping out of gear?


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## brad96z28 (Aug 21, 2005)

Spitz;669838 said:


> Gm has had trouble with the older range switches and such, some even have you install a shield to keep snow and water away from it.. Definatly nothing can be for certain on the internet, best take it into a shop who can see it..
> 
> Service- I usually flush any transmission at 50k or less no matter what the fluid looks like, then again i do my own so its not a big deal to me.. No idea what the recommended changes are though. ATF breaks down just like any fluid though, keep that in mind. The allision isnt much different from any other trans though, just larger with a little more software power behind it.


 I flush them 50k or dirty whatever comes first, no matter who says what.


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## Rangerman (Mar 27, 2006)

Oh brother the guys are right about the range switch weve had that twice in one truck take it to ur dealer they will fix it. As far as the last comment about flushing if u want to buy a need tranny flush. That is the worst thing u could do that stirs up all the metal and gets rid of the sludge. Trannies are like humans theres good and bad colesteral theres good sludge and bad sluge thats why theres a break in period for new trucks.


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## brad96z28 (Aug 21, 2005)

Rangerman;672605 said:


> Oh brother the guys are right about the range switch weve had that twice in one truck take it to ur dealer they will fix it. As far as the last comment about flushing if u want to buy a need tranny flush. That is the worst thing u could do that stirs up all the metal and gets rid of the sludge. Trannies are like humans theres good and bad colesteral theres good sludge and bad sluge thats why theres a break in period for new trucks.


Thats about the stupidest thing I have heard in a long time. How the hell does it stir anything up? It ads no aditional pressure then what the trans puts out. And the fluid flows in the same direction. Ive done hundreds with 0 problems. How many have u done? Please explain how It stirs up contimants in the transmission.


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## Rangerman (Mar 27, 2006)

I have had countless people tell me that mechanics, people who work for allison trans, and what good does it do if its not adding some pressure how do you expect ur filter to get clean if its going the same direction would that be fluid through the filter to the moving parts. Wow seems to me like that would take the new fluid throught the dirty filter and into the trans. Sounds to me like its all adds up to about 3000-5000 down the drain when you can change the fluid so easily.


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## brad96z28 (Aug 21, 2005)

Rangerman;672789 said:


> I have had countless people tell me that mechanics, people who work for allison trans, and what good does it do if its not adding some pressure how do you expect ur filter to get clean if its going the same direction would that be fluid through the filter to the moving parts. Wow seems to me like that would take the new fluid throught the dirty filter and into the trans. Sounds to me like its all adds up to about 3000-5000 down the drain when you can change the fluid so easily.


 Most newer transmissions do not have Filters they have screens and if the fluid never gets very dirty not much of a need to change the internal filter. It is a good idea to change them though periodicly.The flush machine's purpose is not to clean the filter its purpose is to excange 99% of the old fluid for new nothing else.Please exlpain how u change 99% of the old fluid with new please?


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## brad96z28 (Aug 21, 2005)

Rangerman;672789 said:


> I have had countless people tell me that mechanics, people who work for allison trans, and what good does it do if its not adding some pressure how do you expect ur filter to get clean if its going the same direction would that be fluid through the filter to the moving parts. Wow seems to me like that would take the new fluid throught the dirty filter and into the trans. Sounds to me like its all adds up to about 3000-5000 down the drain when you can change the fluid so easily.


Well there like u and dont know what there talking about.Next time the tell u something that dont make sence ask them to explain.Change the filter before u flush it if u where so worried about it.U did not explain how it stirs up debris.


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## Spitz (Feb 28, 2008)

Well a lot of the sediment seems to stick to the pan and obviously the magnet. That and the fluid is a detergent fluid so it suspends as much junk as it can untill it goes through the filter. The allison 1000 does have a serviceable filter in the sump, even though i dont think allison recommends it be serviced. Gm transmissions i've seen that arent taken care of (filter+ flush) usually dont last beyond 100k, alot we do service regularily end up lasting a lot longer. You want to remove the pan, clean it out and replace the filter. This removes a lot of the used oil, makes it easier for the machine to remove (dilute) the rest. But like said it does remove a lot of the used oil, and you need to replace that oil as it does break down (obviously). Look at it, it does get dark and starts to stink. That fluid is 3x as important as motor oil is to a motor. Its the coolant, lubrication and the source of any power the transmission makes.. Its definatly a good idea to keep nice, new fluid in an auto.


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## brad96z28 (Aug 21, 2005)

Spitz have u ever had one come back with shifting problems after u have done a flush? I have Been using the same style machine since 2003 with 0 problems.


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## Spitz (Feb 28, 2008)

Not any that were legitimate. When i say legitimate i mean not even the same part of the vehicle complaints.. You did a trans flush and now my ujoints squeek.. Stupid stuff like that.


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## brad96z28 (Aug 21, 2005)

Spitz;673002 said:


> Not any that were legitimate. When i say legitimate i mean not even the same part of the vehicle complaints.. You did a trans flush and now my ujoints squeek.. Stupid stuff like that.


Ha ha Ya I hear you there. I dident think U have had any problems either . Thanks.:salute:


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## ALC-GregH (Nov 26, 2008)

I've done 100's of tranny flushes and never had a issue.


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## plowboy22 (Jan 19, 2004)

One of my best friends works on durmax for a living you might of seen him pulling his truck for all durmax needs i would call kyle or go to crankitupdiesel.com he nows these in and out.


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## PinkyRingz (Nov 26, 2008)

i took it into the shop and they fixed it for a total of $118.00 cdn.. Problem was an exposed wire (don't ask me why it was exposed) got corroded from salt and what gunk and wasn't transmitting proper. She's all good now tho. Please pass on the info if someone else has the same problimo!


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## LUCKY 7 (Dec 9, 2008)

I say count your blessings and go get a lottery ticket- you are lucky lucky!


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## russ130 (Oct 29, 2002)

I have heard that you shouldn't change your tranny fluid too. Was explained to me that you lose some of the friction that is in the original fluid. Personally I change my fluid and don't believe it for crap plus you can always get a friction additive if that was the case. Personally I see it more as hydraulic fluid than a friction conductor. We all change our plow's hydraulic fluid every year right? Then it only seems right to change your tranny's hydraulic fluid every year too.


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## Spitz (Feb 28, 2008)

The oil simply breaks down over time, use, and because of the heat.. You would never run an engine 100k miles without an oil change, why not with a transmission. The tranmission fluid is used for various things inside a transmission, it conducts hyrdaulic power, its the tranmissions coolant, and its lubrication..


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