[dav2no1]

My bad, I assumed you guys were referring to the 8 speed. Didn't realize the 6 speed had the same issues.

 

[Jstucker1976]

Yes, just cooling line attachment is different. See my post just above yours.

Your TBV should have quick disconnects for the cooling lines.
View attachment 960855

2016-2018 has a retaining plate for the cooling lines.
View attachment 960856

It's easy to double check - it's on left side of transmission just behind the bell housing.

Various YouTube videos say that you can swap out the internals if you get a new TBV and have the old version with quick disconnects.

Yours is a 8 speed so I wasn’t sure if they was different

 

[spaddman]

2016-2018 has a retaining plate for the cooling lines.

My 2015 Sierra 2wd 4.3L 6speed has the retaining plate for the oil lines. There is a small o-ring on each line and the plate is directional also. The 10mm head bolt holding the plate is not centered in the plate. At least it wasn't on mine when I installed a Superior STL010 bypass kit.

 

[a1smith]

Yours is a 8 speed so I wasn’t sure if they was different

We have a 2016 with a 6L80 - the picture of the TBV above with the cooling line retaining plate is from our truck.

 

[a1smith]

My 2015 Sierra 2wd 4.3L 6speed has the retaining plate for the oil lines. There is a small o-ring on each line and the plate is directional also. The 10mm head bolt holding the plate is not centered in the plate. At least it wasn't on mine when I installed a Superior STL010 bypass kit.

Good to know. I thought the changeover was 15 to 16; I guess it was sooner.

The bolt for my retaining plate (2016) wasn't centered either. My guess is they weren't able to center it because of the internal configuration.

I wasn't able to find a torque spec for the retaining plate bolt. The torque for the bolt holding the TBV to the transmission case is 16 ft-lb.

 

[Jstucker1976]

We have a 2016 with a 6L80 - the picture of the TBV above with the cooling line retaining plate is from our truck.

Maybe I was replying to the wrong person. I thought someone said 8 speed. Mine definitely has the retaining plate like the photo. What part number did you use

 

[Supergus]

Anyone know if dealerships will (or have to) replace the original tcbv under this TSB if I can't get any symptoms to appear?

 

[RedSLEd]

In the TSB, it says to replace the t-stat even if the customer's complaints cannot be duplicated. So... you could complain about something outlined in the TSB and they should replace the t-stat (even if that condition doesn't really exist).

 

[jmbrad]

Curious, would this TSB apply to a 2011 6L80 too?

 

[davester3500]

Curious, would this TSB apply to a 2011 6L80 too?

There is a link to the tsb in the first post, with the specific years/models trucks it applies to. You are asking for someone to read it to you?

 

[jmbrad]

There is a link to the tsb in the first post, with the specific years/models trucks it applies to. You are asking for someone to read it to you?

No, I'm asking if a 2011 would benefit from this part change or if it even has a bypass. I can read just fine.

TSBs don't always address every year model. However, many earlier models will suffer from the same issues. This is especially true for recalls.

 

[davester3500]

No, I'm asking if a 2011 would benefit from this part change or if it even has a bypass. I can read just fine.

TSBs don't always address every year model. However, many earlier models will suffer from the same issues. This is especially true for recalls.

They indicate what years/models the tsb applies to. Reading it would clearly tell you if your 2011 truck is covered by it.

 

[jmbrad]

They indicate what years/models the tsb applies to. Reading it would clearly tell you if your 2011 truck is covered by it.

I read it. I see the years.

Let me try to explain this to you, as you seem to have a bug up your bonnet.

I understand the TSB applies to various 2016-2021 models.

When did GM add a Temp Bypass Valve to the 6L80E? 2015? 2014? from what I've read.

I had a failure at 68k miles on a truck I bought with only 53k miles. I've read enough to know these transmissions are especially susceptible to heat. I want to extend the life of my transmission as long as possible. If a Temp bypass valve will extend the life of my 2011 then I want to add one if it's possible. Obviously GM knows there's a problem with the 6L80, otherwise they wouldn't still be tweaking it after over a decade of production. If upgrades will extend the life of mine, then I want to take advantage of them.

I'm asking for help, not a lecture.

 

[a1smith]

I read it. I see the years.

Let me try to explain this to you, as you seem to have a bug up your bonnet.

I understand the TSB applies to various 2016-2021 models.

When did GM add a Temp Bypass Valve to the 6L80E? 2015? 2014? from what I've read.

I had a failure at 68k miles on a truck I bought with only 53k miles. I've read enough to know these transmissions are especially susceptible to heat. I want to extend the life of my transmission as long as possible. If a Temp bypass valve will extend the life of my 2011 then I want to add one if it's possible. Obviously GM knows there's a problem with the 6L80, otherwise they wouldn't still be tweaking it after over a decade of production. If upgrades will extend the life of mine, then I want to take advantage of them.

I'm asking for help, not a lecture.

You can find out quickly if your 6L80 has TBV. It is on the driver's side at the back end of the bellhousing - just follow the ATF cooling lines back to the transmission. Look at post #20 for some pictures I posted. That shows the 2 flavors. The earlier version uses clips to hold in the cooler lines. The newer version uses a retaining plate. The 85585333 TBV is the retaining plate design. If you have the older version with the clips you have 2 options - buy the 85585333 TBV and swap out the internals or buy a TBV delete kit. There are posts above discussing it and the pros/cons of each. It's an easy job - I did it in about 20 minutes in the driveway (I bought 85585333 and have 2016 with retaining plate so only swapped valve, no internals swap).

 

[RedSLEd]

@jmbrad The t-stats started in 2014. Your 2011 has no restriction in the cooler lines and would not benefit from installing the t-stat.

 

[a1smith]

When did GM add a Temp Bypass Valve to the 6L80E? 2015? 2014? from what I've read.

@RedSLEd is right, yours won't have TBV. Your ATF cooling lineset bolts to the back of the bellhousing directly - there is only a block. It looks like this - this is the side going into the transmission.

 

[jmbrad]

@jmbrad The t-stats started in 2014. Your 2011 has no restriction in the cooler lines and would not benefit from installing the t-stat.

@RedSLEd is right, yours won't have TBV. Your ATF cooling lineset bolts to the back of the bellhousing directly - there is only a block. It looks like this - this is the side going into the transmission.

View attachment 961255

Thank you both.

I plan on towing an RV in the near future and I already had the larger cooler installed when I did the rebuild. Just covering the bases.

 

[a1smith]

Thank you both.

I plan on towing an RV in the near future and I already had the larger cooler installed when I did the rebuild. Just covering the bases.

For us, switching to the 70C TBV worked great. Pulling our trailer (with 2016 K2XX 5.3L/6L80/3.42) we used to see just under 200F, now we see low 160F. So, right at 20C drop. Highest ambient so far was about 90F, trailer is 5310# curb weight.

 

[jmbrad]

For us, switching to the 70C TBV worked great. Pulling our trailer (with 2016 K2XX 5.3L/6L80/3.42) we used to see just under 200F, now we see low 160F. So, right at 20C drop. Highest ambient so far was about 90F, trailer is 5310# curb weight.

That's awesome. I wish my truck had 3.42 gearing. I have the loathsome 3.08. All I could find at the time. I'm still debating whether to keep the 2011 or go with a 3/4 ton with a 6.0 or maybe an 8.1 if I can find one. Or, I hate to admit, switch brands. Once bitten, twice shy. I was a loyal GM man for many years, over 35 of ownership to be exact. Never a time without at least one GM in the fleet. The 6L80E has me questioning my loyalty.

 

[RedSLEd]

As long as you rebuilt it with quality stuff and follow the 'severe duty' schedule for fluid changes, etc., the trans should last you at least a couple hundred thousand miles.