2007 Sierra Tranny Repair

Champy · November 26, 2008

Ok - my 2007 Sierra 1500 Crew Cab was leaking a small amount of transmission fluid and I took it to the dealer to have it checked. After searching this site I assumed it was a front seal or something like that. Well they fixed it all under warranty (22k miles) and in addition also fixed the following:

Power Steering Shaft Seal leaking - R&R
Front Brake Rotors Warped - Machined
Rear Brake Drums Turned - adjusted and in spec
Repair Transmission
Re-Conditioned Valve Body and Accumulators
Flushed all fluids and installed filters

So my question for you experts (basically everyone knows more than I do) is what does this description of the repair/failure mean? What caused the leak / tranny problems? The dealer is supposed to call me back so I can talk to the tech directly for more detail.

verbatim from the Service Work Order:

TEST DROVE THE VEHICLE AND FOUND FRONT ROTORS AND REAR DRUMS WARPED.

PERFORMED TRANS DIAG AND FOUND TRANS TO BE SLIPPING IN 3RD AND 4TH. CHECKED FOR CODES AND BULLETINS - NONE FOUND. TRANS MUST COME APART. REMOVED TRANSMISSION AND DIS-ASSEMBLED, FOUND 3-4 CLUTCH HOUSING AND FIBER AND STEEL PLATES BURNT. REMOVED ALL COMPONENTS INSIDE TRANS. CLEANED ALL PARTS, INSTALLED NEW SEALS AND GASKETS. INSTALLED NEW 3-4 CLUTCH HOUSING, FIBERS, AND STEELS. RE-CONDITIONED VALVE BODY AND ACCUMULATORS. INSTALLED NEW FILTER AND FLUID. FLUSHED COOLER AND LINES. FLOW

0.7GPM@69

DEGREES, CYCLE 35, CODE DB46FB7. TEST DROVE VEHICLE. ALL OK AT THIS TIME.

PARTS REPLACED:

PLATE
GSKT KIT
FLTR KIT
HOUSING
PLATE KIT
FLUID
STUD
NUT-MUFFL

Any assistance in better understanding "What" was wrong and possible causes is appreciated.

Bish · November 26, 2008

Ok - my 2007 Sierra 1500 Crew Cab was leaking a small amount of transmission fluid and I took it to the dealer to have it checked. After searching this site I assumed it was a front seal or something like that. Well they fixed it all under warranty (22k miles) and in addition also fixed the following:

Power Steering Shaft Seal leaking - R&R

Front Brake Rotors Warped - Machined

Rear Brake Drums Turned - adjusted and in spec

Repair Transmission

Re-Conditioned Valve Body and Accumulators

Flushed all fluids and installed filters

So my question for you experts (basically everyone knows more than I do) is what does this description of the repair/failure mean? What caused the leak / tranny problems? The dealer is supposed to call me back so I can talk to the tech directly for more detail.

verbatim from the Service Work Order:

TEST DROVE THE VEHICLE AND FOUND FRONT ROTORS AND REAR DRUMS WARPED.

PERFORMED TRANS DIAG AND FOUND TRANS TO BE SLIPPING IN 3RD AND 4TH. CHECKED FOR CODES AND BULLETINS - NONE FOUND. TRANS MUST COME APART. REMOVED TRANSMISSION AND DIS-ASSEMBLED, FOUND 3-4 CLUTCH HOUSING AND FIBER AND STEEL PLATES BURNT. REMOVED ALL COMPONENTS INSIDE TRANS. CLEANED ALL PARTS, INSTALLED NEW SEALS AND GASKETS. INSTALLED NEW 3-4 CLUTCH HOUSING, FIBERS, AND STEELS. RE-CONDITIONED VALVE BODY AND ACCUMULATORS. INSTALLED NEW FILTER AND FLUID. FLUSHED COOLER AND LINES. FLOW

0.7GPM@69

DEGREES, CYCLE 35, CODE DB46FB7. TEST DROVE VEHICLE. ALL OK AT THIS TIME.

PARTS REPLACED:

PLATE

GSKT KIT

FLTR KIT

HOUSING

PLATE KIT

FLUID

STUD

NUT-MUFFL

Any assistance in better understanding "What" was wrong and possible causes is appreciated.

It means they basically rebuilt your trans....on their dime. Clutches were burnt and caused the slipping. Could have been a defect, you could have overheated your trans at some point, you could have abused your trans to cause premature failure. Least likely IMO is abuse as I've been pretty hard on GM trannies and I never had friction material failure at that low a mileage.

Consider yourself lucky it happened under warranty

Champy · November 26, 2008

I can't believe it was abuse. I've only got 22K miles in 14months of ownership and heaviest thing I've hauled is a load of mulch or towed my popup trailer. Never buried it in a muddy field or such things either.

I was trying to better understand the root cause to avoid more problems later on - or to know what to watch out for - I just bought a 23' Hybrid TT and need to be able to haul it safely / reliably.

BTW - it certainly shifts much better now.....maybe something was wrong from day one....

mrmadwrench · November 27, 2008

you said the trans was leaking fluid.if the fluid got low enough over time the trans would start to slip causing the trans failure.a 3-4 cluch failure in 4l65e would cause a noticeable flair/slip.the leak was probably the front pump seal. the pump has 2 sides if not aligned properly the seal will leak. i had this problem with mine.

Bish · November 27, 2008

you said the trans was leaking fluid.if the fluid got low enough over time the trans would start to slip causing the trans failure.a 3-4 cluch failure in 4l65e would cause a noticeable flair/slip.the leak was probably the front pump seal. the pump has 2 sides if not aligned properly the seal will leak. i had this problem with mine.

Excellent point. Also, do you have an aux cooler for the trans? If not, I could believe overheating. Even the factory aux cooler isn't all that great but it handlesd most of my towing needs.

pm26 · November 27, 2008

My neighbor destroyed the transmission in his '04 1500 Sierra 4x4 at 32k miles, but he was frequently pulling a 9k lb trailer with the truck and not using the tow mode.

Champy · November 27, 2008

you said the trans was leaking fluid.if the fluid got low enough over time the trans would start to slip causing the trans failure.a 3-4 cluch failure in 4l65e would cause a noticeable flair/slip.the leak was probably the front pump seal. the pump has 2 sides if not aligned properly the seal will leak. i had this problem with mine.

I saw the leak coming down at the front of the pan, it wasn't a gusher and the tranny fluid never really got that low before seeing the dealer. I really expected a pump seal leak - not the whole rebuild scenario. I agree and am glad it was all under warranty too. Maybe I should swap out the factory oil cooler for something better.....

ETEE · November 27, 2008

The inordinate amount of work done on the brake system at 22K makes me wonder if it is technically possible for the brake system electronics to malfunction, allowing additional loading of the transmission, causing premature failure. I had that problem on a 95 Jeep Grand.

c4cruiser · November 27, 2008

The inordinate amount of work done on the brake system at 22K makes me wonder if it is technically possible for the brake system electronics to malfunction, allowing additional loading of the transmission, causing premature failure. I had that problem on a 95 Jeep Grand.

I would think that brake problems would have been noticed by the driver. It takes a lot of heat to warp rotors and drums and there should have been some indication like smell.

My first impression when I read the diagnosis and repairs was that abuse could have been the cause for both problems. Hard acceleration, WOT shifts, manual downshifting at high RPM's and excessive braking would have seemed to be reasons for the problems.

With no history of towing or hauling really heavy loads, a factory trans cooler should have been enough to keep the trans fluid within specified temp ranges. Certainly a trans fluid leak where tfluid level was never checked could contribute to failure, but the OP never said that he didn't check and maintained a proper fluid level.

In any event, with a new trans and going to haul a new larger trailer, I would definitely add a larger trans cooler and keep a close eye on trans temps when towing. Also, consider doing a tranny service at whatever intervals as recommended in the owner's manual when towing.

Champy · December 1, 2008

Ok - so a quick update on this topic.....

I can't believe (as c4cruiser noted) that my problems were the result of abuse - but I've been wrong so many times before anythings possible. Since the repair and due to comments / suggestions in this forum, I started watching how I actually drive the truck. Well I rarely get it above 2k rpm before it shifts; have never done a WOT accel; nor a downshift at high speed' etc.... Regarding the brakes - I too thought it strange to have this repair without having noticed a problem or questioning what should have been an obvious brake rumble / shudder. If asked to make a WAG on it I would presume the dealer loaded on some warranty work to recover more from GM...but again, what do I know.

Regarding the tranny cooler.......factory cooler installed already. Here's some recent data for everyone to ponder. BTW - the temp values shown here are what was displayed on the digital display info center...so I'm not sure how accurate they are... Drove to Lexington Ky and back today (~400mi round trip); 4 adults; no trailer/loading; about 45deg weather / 37deg on return - with these tranny temps noted:

105 deg first 50 miles on local highway speeds...60mph / 1700 rpm
120 deg running on the freeway with cruise control at 75mph / 2100 rpm most of the way
185 deg return trip caught in stop-n-go traffic for 15miles on freeway; ~ 45mins
120 deg after above delays & 30 mins at 70mph temps returned to prior norms

So - given the above running temps - do I need to replace/upgrade the tranny cooler before hauling the 4500lb travel trailer?

GuyGene · December 1, 2008

Since I just had a tranny rebuild on mine, I would definitely go for an after market, bigger cooler for it. I did for mine, too late, I guess, but at least it's on now.

Wow, the stop/go traffic really hurts! I was surprised at the difference.