6L80 Help Needed!!!!

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DarrinHarvey1974

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I have a 2013 GMC Yukon XL 1500 SLT 5.3 with 6L80 transmission and 203,000+ miles. The problem I’m having, when I first start the truck and drive it, it drives and shifts fine until the transmission reaches 180°-190° at this point if I come to a complete stop and then press on the gas it won’t drive. But, when I turn it off and them on again it will shift right into drive and/or reverse with no problem. Once I brake and come to a complete stop and press the gas, there’s no movement, it doesn’t drive until I turn the truck off and then on again. I also hear a whinning noise coming from the transmission sometimes when it's started and soetimes when shifting into 2nd (the sound is similar to the noise that comes from the PS when the fluid is low... but the noise isn't coming from my PS). I want to get a idea of what the problem may be before I drive into a transmission shop and they overcharged me for something that’s not the problem.
 
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DarrinHarvey1974

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Thank you, for the help... you sound very confident in your response and I will have this looked at ASAP, but if either of these are NOT the problem where else can or should I look?
 
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NickTransmissions

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I have a 2013 GMC Yukon XL 1500 SLT 5.3 with 6L80 transmission and 203,000+ miles. The problem I’m having, when I first start the truck and drive it, it drives and shifts fine until the transmission reaches 180°-190° at this point if I come to a complete stop and then press on the gas it won’t drive. But, when I turn it off and them on again it will shift right into drive and/or reverse with no problem. Once I brake and come to a complete stop and press the gas, there’s no movement, it doesn’t drive until I turn the truck off and then on again. I also hear a whinning noise coming from the transmission sometimes when it's started and soetimes when shifting into 2nd (the sound is similar to the noise that comes from the PS when the fluid is low... but the noise isn't coming from my PS). I want to get a idea of what the problem may be before I drive into a transmission shop and they overcharged me for something that’s not the problem.
At 203k on the clock, it's time for an overhaul. Your symptoms are much more indicative of worn applied elements, slipping rear sprag or possibly sticking #1 check ball but at this point, I'd yank the unit out and overhaul it.

Check out my 6L80 Info thread for tech resources, parts lists, procedural instruction and relevant discussion - link is in my sig line.
 
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DarrinHarvey1974

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At 203k on the clock, it's time for an overhaul. Your symptoms are much more indicative of worn applied elements, slipping rear sprag or possibly sticking #1 check ball but at this point, I'd yank the unit out and overhaul it.

Check out my 6L80 Info thread for tech resources, parts lists, procedural instruction and relevant discussion - link is in my sig line.
That's what I was trying to avoid, almost every shop I called quoted me MORE than $7000 for 6L80 rebuild!
 

petethepug

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WOW! That sounds like dealership pricing.

There’s new technology available now or around the corner to add a 8 or 10 speed trans. Why is this a big deal? Less wear on motor, better milage, quieter operation and better acceleration.

If you have a diesel truck specialty shop, that would be the place to get a bid. They can rebuild and upgrade these trans with their eyes closed.


 

MWD_CTSV

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Agree with Nick, 200k is a good run. Time for an overhaul. Most reputable shops will replace everything to avoid future problems or a comeback. It isn't work doing a partial job.

I think you can get a GM trans for a little less, and it does come with a warranty, but no real upgrades. Still likely will last the life of the vehicle (another 200k).
 

MWD_CTSV

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I have a 2013 GMC Yukon XL 1500 SLT 5.3 with 6L80 transmission and 203,000+ miles. The problem I’m having, when I first start the truck and drive it, it drives and shifts fine until the transmission reaches 180°-190° at this point if I come to a complete stop and then press on the gas it won’t drive. But, when I turn it off and them on again it will shift right into drive and/or reverse with no problem. Once I brake and come to a complete stop and press the gas, there’s no movement, it doesn’t drive until I turn the truck off and then on again. I also hear a whinning noise coming from the transmission sometimes when it's started and soetimes when shifting into 2nd (the sound is similar to the noise that comes from the PS when the fluid is low... but the noise isn't coming from my PS). I want to get a idea of what the problem may be before I drive into a transmission shop and they overcharged me for something that’s not the problem.
The transmission pump is an offset vane drive pump just like the power steering pump, so similar sounds for problems would be expected, although I have never heard a whining 6L80 transmission pump.

As Nick pointed out, the engagement for forward movement requires pressure from the pump and the lack of movement typically indicates severe wear in either the frictions or the pump. Realistically they go together because the frictions wear out fast with low pressure and the pump wears out fast with the metal shavings from the frictions wearing, which causes low pressure, so it can go downhill very fast. At higher temps the fluid flows past all the worn seals or worn pump vanes, so pump and clutch engagement will all be worse at higher fluid temps.
 

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