NOTE: I'll try this again. Apparently I didn't follow the instruction quite close enough after I registered yesterday and my original post never appeared on the forum. Note to self, read the instructions better. Hopefully my first post isn't being reviewed by a moderator as some forums do before allowing a new member to post.
I'm new to this forum though I have read through several posts trying to understand a few things before I joined and started asking questions. To start, I'm not a tuner nor a transmission expert. So bear that in mind if you reply as I might not understand all of the terminology. I don't insult easily so if you add something that is patently obvious I certainly won't get offended. A lot of the information below is mechanical information. But the end goal here is to see if I can't use the tuner software to both diagnose a failing torque converter and to tune it so the torque converter last the longest.
My job requires a lot of technical writing and many people get understandably frustrated in how I write what I write. In this case I'll start out with the questions and put some backup information at the end of the post.
Questions:
1.) Can tuning software be used to help diagnose a failing torque converter?
I think the design of the stock 6L80 torque converter generates too much heat during lock up. See the 'Background information below for more details. Basically I'd like to temporarily remove the lock up from all 6 gears and see if the amount of heat generated decreases. I'm trying to diagnose if my torque converter is failing. If I can come to that conclusion I'd be willing to replace it now before it causes any additional damage.
2.) What is the 'Slip' that is often discussed as being reduced or eliminated in the tuning software?
I just don't understand what this 'Slip' is referring to.
Background:
Vehicle:
- 2010 Silverado WT. 5.3 L, with 350,000 miles on it. 6L80 transmission but it does not have the 'Towing Package' so it has a 'standard' cooling system. I do not tow anything.
- Transmission was rebuilt at 197,000 miles by a very reputable shop and I chose the best rebuild available. 100,000 mile warranty and $4,300.
- Transmission failed again at 304,000 miles. Yes that's only 107,000 miles and no, I didn't get a discount on the second rebuild. I chose the basic rebuild with a 12,000 mile warranty and $2,800. (smart/stupid decision is another topic)
- I have addressed the heat issue by installing a deep transmission oil pan and a transmission cooler. I can now keep the transmission at 185 in 105 degree heat. Next 114 degree day we'll see how well it does, but i expect it will still be below 200 degrees. But I don't think that solves the problem. I 'think' there is a mechanical problem in the transmission that causes too much heat to be generated and removing the heat quicker doesn't address that 'potential' issue.
Driving Conditions/Habits
- I live in Arizona (Phoenix Area) and temperatures of 115 degrees F are not uncommon. I'm pretty sure that puts me into what manufacturers call 'Severe Duty". Transmission temperatures in the winter isn't a problem.
- I sometimes drive in the mountains and sometimes drive off road. I never tow anything.
Temperatures:
I started tracking the transmission temperatures after the first rebuild as I suspected temperatures were at least a contributing factor in the first failure.
- Before the first failure I'm was convinced that the transmission temperatures were 185 degrees all the time. But before he first failure I didn't really pay that much attention other than to see what it was from time to time. And I can't really remember if my reading of 185 degrees was during the winter or summer. So my baseline isn't terribly reliable.
- GM states that the normal operating temperatures are between 180 and 200 degrees. But what we don't know is if that includes in my 'Severe Duty'. I suspect not.
- In general running at 70 MPH in 100 degree heat would generate transmission temperatures between 200 and 210. The harder I drove it, the higher the temperature would go.
- Driving at 70 MPH in 105 and above would generate transmission temperatures between 210 and 220. Again, drive it harder and it got hotter. Kind of what you'd expect.
- Driving at 80 MPH in 100/105 caused higher transmission temperature. Driving in 115 degree temperatures created higher temperatures at both 70 and 80 MPH.
- At 70 MPH in 102 degree heat gong up a 6% grade the transmission temperature reached 235 and I stopped to cool it off.
- There are other extreme conditions that are outliers but too much information doesn't really help. My impression is that the transmission generates too much heat and I think a failure is imminent.
Transmission Design Deficiency:
- I have read that the stock 6L80 torque converter was made with a pressed steel cover. And that cover has a tendency to flex during lock up causing heat and damage to the coatings on the mating surfaces. I understand that most who want a 6L80 to last or know it will be put into 'Severe Duty' purchase an aftermarket torque converter made from billet steel to address this concern. There is a good series of videos on the 6L80 and part 2 ( https://www.youtube.com/watch?v=UeI64HjS_Xc ) goes into this defect. The third part in that series goes into tuning the 6L80 to make the torque converters last. A lot of this made sense and being it was on the internet it 'HAS TO BE TRUE'. So say so if you think I'm overthinking this whole issue. I won't get offended.
- After the second rebuild I had the transmission fluid changed at 20,000 miles and the fluid was dark and there was some metal attached to the magnet in the pan. It was changed by my mechanic. I just changed it myself after another 20,000 miles and the color was dark again and there was a build up of particles attached to the magnet. I would not have thought the fluid could get that dark in 20,000 miles and I thought the amount of metal attached to the magnet was significant. But I'm not a transmission expert. FYI - the metal attached to the magnet feels like a slimy goo (mix of ATF and metal) and although I didn't measure how thick it was, it was thick enough to measure with a set of calipers.
Tuning Software
I don't posses the tuning software/hardware though I'm not object to getting it. $500 seems a lot for testing a transmission and finally setting it up for best service life, but on a side note I'd like to test removing DoD to see wht it does to gas mileage. As I understand it the 5.3 L engine got 21 MPG before DoD was introduced and it now gets 15 MPG. FYI the 21 and 15 are real world reports from users over the years, not rated estimates. But maybe the changed something else in the engine when they changed to DoD and it'll still be 15 MPG.
Reply With Quote
Originally Posted by hjtrbo
