Are the valve body seals a culprit with converter failures?

[dkad260]

So I'm still thinking about replacing my converter as preventative maintenance. I spoke with a couple local shops and they mentioned one area of concern are the valve body seals.

For those that are in this business, does the converter fail mainly from an inferior clutch or from pressure loss from worn seals? Curious to the ratio of both.

Would it be wise to replace the valve body seals when replacing the filter or can this cause more issues if the valve body has never been removed.

The converter is on the list of things to do but likely next summer.

Dealer did a flush at 60K, I'm at 130K and will be replacing the fluid soon. Currently no issues with the trans.

All input appreciated.

 

[OR VietVet]

I wish that over the years, I was in and ran shops, that I studied and learned auto transmissions better than the very small amount that I know. Hopefully @NickTransmissions and @rockola1971 will chime in with their collective knowledge about this concern.

 

[petethepug]

2010 Denali AWD, yes replace the TC buy save it for when the trans is removed to swap out the motor & trans mount, rear mail, front diff bushings etc. Changing the fluid is #1 but the TC getting off balance and taking out the rest is #2 that kills the trans.

 

[strutaeng]

It seems like the torque converter failure is due to the thickness of the internal clutch plate. Probably some GM beancounter reduced the thickness to save a few pennies when they modified the ZF unit (among other things.)

Undersize some part that gets a good amount of stress means it's going to fail at some point, most likely after the warranty expires.

 

[dkad260]

2010 Denali AWD, yes replace the TC buy save it for when the trans is removed to swap out the motor & trans mount, rear mail, front diff bushings etc. Changing the fluid is #1 but the TC getting off balance and taking out the rest is #2 that kills the trans.

Thanks, good tips, and yes, I did recently change all those mounts, front diff, both motor, and trans mount..also replaced both F&R driveshafts.

 

[NickTransmissions]

So I'm still thinking about replacing my converter as preventative maintenance. I spoke with a couple local shops and they mentioned one area of concern are the valve body seals.

For those that are in this business, does the converter fail mainly from an inferior clutch or from pressure loss from worn seals? Curious to the ratio of both.

Would it be wise to replace the valve body seals when replacing the filter or can this cause more issues if the valve body has never been removed.

The converter is on the list of things to do but likely next summer.

Dealer did a flush at 60K, I'm at 130K and will be replacing the fluid soon. Currently no issues with the trans.

All input appreciated.

Its up to you but to remove/reinstall the valve body (VB)-TEHCM assembly, you'll need a SnapOn 10EPL socket (or inverted T12). As long as you're aren't replacing the TEHCM or doing anything with the valve body itself you won't need to run a fast adapt relearn before driving it again. VB-to-case bolts take 71 inch lbs of torque.

Here's a short list of why the torque converters fail so frequently in 6L80s:
> TCC is way under-designed at only .020-.025" thick whereas a clutch twice that thick is called for in those units
> TCC regulator valve wear in the lower valve body
> PR, TCC control and TCC limit valves in the pump cover
> Overheating due to malfunctioning (or correctly functioning) TBVs in 2015+ vehicles

 

[dkad260]

Thanks @NickTransmissions , very helpful. Replacing the seperator plate in my 4L60E with a check ball nearly punched through the plate saved that trans at 160K, along with a vette servo, so that worries me with this one if they are prone to do the same.

Would a new or rebuilt valve body require a relearn if all stock? Or if I went that route, would any mods to the VB be wise or leave it stock?

 

[NickTransmissions]

Thanks @NickTransmissions , very helpful. Replacing the seperator plate in my 4L60E with a check ball nearly punched through the plate saved that trans at 160K, along with a vette servo, so that worries me with this one if they are prone to do the same.

Would a new or rebuilt valve body require a relearn if all stock? Or if I went that route, would any mods to the VB be wise or leave it stock?

You're weclome.

Yes, replacing, overhauling or modifying anything in the VB will require a fast adapt relearn (any bi-directional scan tool should be capable of resetting the adapts).

The 6L80s have a similar problem w/stuck check balls...#1 check ball gets stuck and you don't move forward; if the #5 check ball gets stuck you lose reverse. Install the Sonnax zip kit if you're going to go through the VB...It will have several parts that address common issues and include new torlon check balls...Also replace the spacer plate. They feature bonded gaskets so the plate/gaskets are all one part.

while you're at it, look at the TEHCM's pressure switches and if you see that the seals are worn/hardened and/or any of the diaphragms are cracked, replace all of them as well (Transgo makes a kit for that). Test the TEHCM w/a multimeter following my instructions in the 6L80 Information Thread (link in my signature line).

Reply back w/any questions.

 

[dkad260]

Thanks again,

Being down one vehicle and not having a spare, makes this service more of a "don't mess with what's working" type of scenario. I'm comfortable enough to do it but should I wait till summer when the Yukon can sit for a few days if needed is my dillema.

I could likely knock all this out in a day or weekend if I have all the parts, the VB being the easiest laborwise.

I have a Tech 2 clone if that will re-adapt the trans then we're good there.

One thing that kinda prompted me to get this ball rolling may or may not be related, and could be the hill hold feature.....

This only happened a couple times in the last month, but taking off from a stop, now I don't want to use the term "slip" since that has a different feel, but it was a delay if you will....almost like you had a banana peel under the tires or were on ice then grabbed some traction on snow before it moved. It wasn't pressing on the gas then a sharp hit or slippage, but a soft "bump" before the truck moved. I was thinking the hill hold feature was activated and released in a way to provide this feeling. This is what made me think of the check balls and if this is the case, then would increasing the RPM off idle provide enough pressure to release the ball if this is in it's infancy?

 

[donjetman]

So I'm still thinking about replacing my converter as preventative maintenance.

All input appreciated.

Almost 5 yrs ago at 130k miles, I installed a TC and a few associated seals/o-rings as preventative mx. Its still going strong today at 192k miles.
https://www.tahoeyukonforum.com/thr...7-yukon-denali-6-2.108334/page-3#post-1293118