Fire123

Just bought my truck a month ago. About a week later, I noticed a 'surge' about a second after trans shifts into 2nd gear. Seems to get more noticable after it warms up. As I stop quickly, there is a soft clunk when it downshifts and I'm almost at a stop. Only 24,000 miles on it. Any ideas? Taking it to the dealer on friday.[&o]

Chevyguru

Thats about how many miles I had on my 1/2 ton crew cab Z71 when it blew third and fourth gear towing and empty utility trailer. pretty well no notice except I thought it sliped the day before. but Chevrolet took care of me and replaced it no questions asked.

Fire123

The dealer labeled my 'surge' as "normal tranny function". I think I might go to a different dealer for a 2nd opinion!

sailor

Fire123 - did you ever get a resolution? My truck is doing the same thing - 2004 Z71 crew.

mmjsport

Hope this helps, A moderator I think/GM tech told me about it. Alot of people have the same issue. It has to do with the slip yoke needing to be lubbed. Hope this helps. Tell the dealer you want your slip yoke lubbed up!

#PIP4020F: Groan Clunk Or Bump Noise From Launch Or At Stop - keywords moan pop squawk start - (Oct 30, 2008)
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[align=left] [align=left]



Subject:
Groan, Clunk or Bump Noise From Launch Or At Stop[/align][align=left]



Models:
2007-2008 Chevrolet Silverado[/align][align=left]




2007-2008 GMC Sierra[/align]


[hr]


This PI was superseded to remove parts request. Please discard PIP4020E.

[hr]


The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may comment that their new body style full size pickup makes a groan, clunk or bump noise at parking lots speeds on launch or with light to medium braking. Braking to a complete stop can force the propshaft slip yoke forward into the transfer case while the vehicle rebounds slightly backwards after stopping its momentum and create this noise. This noise may also be due to fuel movement in the fuel tank when not completely full.
Note:This PI does not apply to the Silverado or Sierra classic versions.
Recommendation/Instructions:
Root cause may be the interface between the rear propshaft slip yoke and the transfer case or transmission output shaft splines or fuel movement in the fuel tank. To isolate if the concern is the slip yoke or fuel slosh and not a brake noise the dealer may attempt to duplicate while coasting with the transmission in neutral and braking to a stop. If a groan noise is gone while braking in neutral the noise is slip yoke related. Dealers may lube the slip yoke splines with TransGel (J36850) to help reduce the noise.
If a clunk noise continues after completing the above, the noise has now been isolated to the fuel movement in the tank please make no repair attempts at this time as this noise is considered a operating characteristic.
If the noise can be isolated to the driveline, lubricating the slip yoke may only be a temporary repair and at this time engineering is investigating this concern.
Note:This PI does not apply to the Silverado or Sierra classic versions. [/align][/align]

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If you have a question, ask it in the forums. I will no longer be answering questions sent to my email.

mmjsport

Do a search for slip yoke, or transmission problems. It's a common problem that GM is trying to figure out a permanent solution. If I find some more info I'll post it up. Good luck.

sailor

I think he is experiencing something different....as I know I am.

Rastis

Sounds just like my silverado. Dealer continues to lube splines and rear suspension, ongoing problem. It appears something besides lubing needs to be done.

mmjsport

Oh, well Same GM tech also posted this? Maybe this has something to do with it?

#PIP4530: Transfer Case Overfull Vent Leak Or Repeat Transmission Concerns - keywords 2ML70 4L60E 4L70E 6L80 6L90 - (Nov 12, 2008)





Subject:
Transfer Case Overfull, Vent Leak Or Repeat Transmission Concerns
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Models:
2009 Cadillac Escalade[/align][align=left]




2008-2009 Chevrolet Avalanche, Silverado, Suburban, Tahoe[/align][align=left]




2008-2009 GMC Sierra, Yukon, Yukon XL[/align][align=left]




Equipped with Magna Transfer Case RPO Codes NQF, NQH or NQG[/align]


[hr]



The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Customers may comment on transmission slipping or surging, transmission fluid is low or a leak out of the transmission vent. Technician's may find that the transfer case is overfull.
Recommendation/Instructions:
The above listed concerns may be caused by the transfer case input seal allowing fluid to migrate out of the transmission into the transfer case. If the vehicle has transmission concerns such as slipping or surging and or this is a repeat transmission concern, or there is a fluid leak from the shared vent inspect and if necessary replace the transfer case input shaft seal. See photo below for a typical seal concern.



_____________________________


If you have a question, ask it in the forums. I will no longer be answering questions sent to my email.

sailor

mmjsport - thanks for posting that one!!!!