Dilemma - Rebuild Transmission or Replace with Low Mileage

[Bruce]

My 2007 Sierra Denali that is just under 140K miles has a transmission issue. The transmission is an early 6L80 and the engine is a 6.2 V8. It does not slip. It does not strand us. But it does throw check engine lights and occasionally locks itself in third gear in limp mode. Clearing the error code makes it normal again. Over the last year I have seen check engine lights around six times and it went into limp mode once. The check engine lights are for solenoid issues.

Before the Bimini trip I spent $1300 on two rounds of electical components replacing all of the solenoids which included the transmission control module and the speed sensor since it was also part of the error code. Replacing these components seems to have made the issue worse. I now see CELs every couple of days and limp mode at least once a week. Driving through hilly terrain at low speed seems to cause the most issues. The issue seems to focus around the 2 to 3 shift and may be due to this TSB.

Book value on the truck is around $20K so I need to fix whether I keep it or not.

I have talked to three transmission shops about what to do. Two shops do not want to open it up and suggest replacing it. They do not have experience with the 6L80 and do not seem to want to mess with them. The mechanic at the shop that replaced the electrical components wants to open it up and rebuild it after hours.

So my options are

Allow the mechanic to pull the transmission, perform the TSB and replace anything else he finds broken inside. Cost for this is $600 labor and $500 plus in parts. If it works I will likely be $1100 to $1500 further into this transmission but will still have some 140K mile parts in it.

Purchase a low mileage transmission for $1400 delivered, pay another shop $350 to install it and spend another $150 having it towed to the dealer and programmed. This will cost around $1900 and the truck would have a 2010 or newer 20K or fewer mile transmission that does not need the TSB performed with a 6 month warranty. A rebuilt transmission with a 100K warranty would bring the cost up to around $3200. The old transmission would have some parts value which would reduce the cost.

I have been shopping for a newer truck for a while and have planned to upgrade near the end of the year. The brakes are upgraded to EBC Green Stuff and slotted and cross drilled rotors. The tires and wheels are upgraded. It is a loaded Denali with almost every option that I bought when it was two years old. With a repaired transmission I might decide to keep it longer.

What do you suggest?

 

[Wayloncle]

I haven't seen great luck with rebuilding from transmission shops, my wife's "04 Tahoe trans went out at 76,000 miles and I had it replaced with a new one at the Chevy dealer for $1500. I'm thinking yours is a 6 speed so that's why more $$, hers is the 4 speed.

If I were in your shoes, I'd go with the 100K mile warranty one, it'd be good for you if you keep it and it's a good selling point if you sell it, it'll probably be worth about that to a new owner...

 

[JC6275]

If you are sure you will be upgrading by the end of the year, I would go the route of used low mileage with 6 month warranty. That will get you just past the beginning of next year with a warranty.

 

[txav8r]

I have to agree. If your trading, go the cheaper route with the warranty.

 

[JC6275]

The transmissions in the early to mid 2000s GM Trucks and SUVS are notorious for having a short life span, the 4L80 and 6L80 both same problems. And as you know they are very expensive to repair or replace.

 

[biglar155]

You've crossed the threshold that I fear is coming for me... I LOVE my 'Burban. It's loaded with all the cool stuff I won't be able to afford on my next ride. Nothing major with engine or tranny YET - but I know it's coming "someday."

I'm at the stage I start calculating it in terms of "car payments." I figure a car payment will be around $500 / mo. So if you're only going to keep it for 3 months, then go the $1,400 route. If you're keeping it for 4 months go the $1900 route. Planning to keep it for a 6 months or more? Go all-out.

I had to do this with our minivan. We had about $1,800 worth of repair on it right before Christmas (computer blew up and caused other issues). In that case, it was nearly the value of the vehicle. I held onto it until March to "get my money out of the repair" and then sent it packing.

 

[1rjclark]

Rebuild from a real tranny shop so it actually handles what you tow

 

[Bruce]

Rebuild from a real tranny shop so it actually handles what you tow

That is the surprising part. I do not have any of the typical symptoms of transmission failure despite towing 13K trailers. It seems that the transmission components have held up with the exception of the defective clutch housing that exists on all pre 2009 and some 2009 6L80s. Unless we take it apart we will not know for certain.

 

[jetboater4life]

I would go with option 2

 

[PEARCE]

If you like the truck and want to keep it for a while then I would go all out with a new transmission. If you want a new truck anyway then go with the used one and get out of it after Christmas. I was under the impression that you were only considering a new truck because of the issues with your current one.

 

[Zarrella]

I say....clear the codes and trade it in!