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10-07-30-001D Fluid Oil Leak During Cold Weather from Transmission Vent - (Feb 22 2013) Automatic Transmission Unit

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Subject:Fluid/Oil Leak During Cold Weather from Transmission Vent

#10-07-30-001D: Fluid/Oil Leak During Cold Weather from Transmission Vent - (Feb 22, 2013) Automatic Transmission Unit

Models: 2001-2013 Chevrolet Silverado 2500HD-3500HD Series
2001-2013 GMC Sierra 2500HD-3500HD Series
Equipped with Allison® LCT 1000 Automatic Transmission (RPOs M74, MW7)

This bulletin is being revised to add the 2013 model year, update the Important statementand add a Note. Please discard Corporate Bulletin Number 10-07-30-001C (Section 07– Transmission/Transaxle).

Condition

Some customers may comment on a small red fluid/oil leak during cold weather. Uponfurther investigation, the technician may find a small fluid leak in the area at theback of the transmission by the vent.

Cause

This condition may be caused by fluid being discharged out the transmission vent dueto a low transmission fluid fill. During extreme cold weather, (approximately -25°C(-15°F or colder), low fluid fill can cause the transmission pump to ingest air whichcan aerate the fluid and push some fluid out the vent.

Correction

On 2001 through 2013 models, verify the transmission is full of fluid. Follow theSI fluid checking procedure to PROPERLY check the transmission fluid level using theHot Check Procedure.

Important:Ensure that the fluid level is at the top of the HOT band when the transmission fluidtemperature is 79°C (175°F). Refer to SI Document ID# 2408059 for the proper fluidlevel checking procedure.

Note:The fluid level on the indicator may be higher on one side than the other. The lowerreading should be considered the actual fluid level. The higher fluid level on theindicator should be considered splash.

#10-07-30-001D: Fluid/Oil Leak During Cold Weather from Transmission Vent - (Feb 22, 2013) Automatic Transmission Unit

Note:Only on 2001-2004 models, replace the transmission fluid indicator (dipstick) witha new vented indicator, P/N-15794381.

GM bulletins are intended for use by professional technicians,NOT a "do-it-yourselfer".  They are written to inform thesetechnicians of conditions that may occur on some vehicles, or toprovide information that could assist in the proper service of avehicle.  Properly trained technicians have the equipment,tools, safety instructions, and know-how to do a job properly andsafely.  If a condition is described, DO NOT assume that thebulletin applies to your vehicle, or that your vehicle will havethat condition.  See your GM dealer for information on whetheryour vehicle may benefit from the information.

#10-07-30-001D: Fluid/Oil Leak During Cold Weather from Transmission Vent - (Feb 22, 2013) Automatic Transmission Unit

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