4L80E questions/problems?

[DickWells]

Looks like I've been absent for over a year!

[JohnC]

Where ya bin?

[Edit] Ah! I see your other thread explains a lot...

[DickWells]

Awe, heck! I just wrote, for over a half-hour, and lost everything, again!
I've looked everywhere, on here and can't see a place to "save"! I need some help, long before I try to post anything! So far, I've spent close to 1.5 hrs, over 2 days and lost all but my heading and yesterday's first line!
So, tell me. How do I hang on to what I'm writing?!

[JohnC]

Well, you did OK on that one (above)... What are you doing differently?

One thing I've done a couple of times is to select a huge block of text without realizing it,then, the next thing you type replaces it. It's a problem if oyu have a touch pad below the keyboard...

If you catch it in time sometimes you can type <ctrl>Z and undo it.

[arveetek]

If I know that I'm going to make a longer post, I will click on the "go advanced" button at the bottom of the Quick Reply box, or on the "reply to thread" button at the bottom of the last post. That will open a new page where it's easier to type everything in. I tend to have better luck doing that instead of using the Quick Reply box that automatically pops up at the bottom. It's way to easy to accidentally click on the "cancel" button instead of the "post quick reply." Don't ask me how I know!

Casey

[DickWells]

OK, I'll try just itemizing the details, up to the onset of a problem.
*95 Burb 6.5 TD 2500 W/ 4911 mech pump, phaser timing, big IC, 4" exhaust, US Shift-Quick4 tranny control.
*Rebuilt 4L80E in May 19+ months ago, out of 1 year warranty.

Couple weeks ago, noticed minor noise in ( what I perceived) as trans. Hollow, maybe, light mechanical, not noticeable, inside, only idle at outside. Checked fluid, cold. Down some added 1quart. Drove till above 140. Added~ pint to bring to full-hot mark. Oil doesn't smell and looks clean as new. This is first time I've had to add, since rebuild. Was fine, less than 2 months ago and trans has less than 5000 m, in 19 months.
Five-6 days ago, started cold at ~mid-teens. Warmed for ~5 min, put in Dr, stalled! Warmed some more, would idle in Dr, then, take throttle to drive around driveway loop ~200 yds. Trans noise noticeable, inside, and feet, hands, butt, told me to shut down. Not loud, but seemed like interference between gears, or something. And, Quick4 display was black!
Next day: Checked Q4 for power. Nope. Found 12V to and through -good 7.5A fuse, but not at pin 9 at display/control. Sun went down, so, waited till warmer, next day. Dash panels out, q4 control in hand, pin 9 has 12V!!! But, the display now has only US showing and won't change when I start engine and shift into gear. Should show P R N 123.
So, here we are. Couldn't call US Shift, because of weekend and holiday,BTW.
As always, looking for advice, experience, expertise, commiseration, etc.

[Robyn]

Almost sounds like the lockup converter or it's controls have an issue.

Stalling in drive is indicative of a messed up converter....

The controller may have died

[DickWells]

Thanks, Robyn. Any simple checks that I can do, from underneath? I'll get under an check for loose wires, etc, as well as call US Shift.
If nothing obvious appears, I'll probably take it over to Bill, the guy who R&R'd it, for taking it to the trans shop in Show Low and back. BTW, that shop's claim to fame is, that he replaces all the electronics in the gearbox. That's (supposed) to be why it cost me over 3 grand!
Question. Given what I've told you about it, what are your thoughts on towing it in neutral for the ~8 miles, over to Bills? I was already thinking that I'd disconnect the driveshaft, but, if it's not necessary - - - ?

[DmaxMaverick]

Sounds like a controller fail as Robyn said, or it's not getting power where it should. If the controller computer isn't happy, stop there. Definitely get it over to your tranny upfitter guy.

No problem towing a 4x4 in Neutral, as long as the Neutral we're talking about is the transfer case. NO tranny neutral towing though, for one mile or 8 (short of a dire emergency). Just get the transfer case in neutral.

[DickWells]

Oh, for cryin out loud! This getting old isn't funny! You probably aren't as surprised as I was, just now, when I read what you said about the transfer case and it hit me like a ton of bricks. If you hadn't written that, I have no idea when I would have come to. Probably, when I mentioned to Lance that I was getting ready to disconnect the driveshaft.
Well, anyway, thanks for the response, Maverick.

[Robyn]

I am not sure on towing that rig with the Tcase in N

Personally I would unhook the rear drive shaft at the diffy....Tape up the joint so the caps don't fall off (Duct or gorilla) and wire the shaft up safely out of the way.....

Some T cases can be towed wheels down....Others NO

The T cases are oiled by a pump.....Some oil properly in N some do not......

You already have an issue to deal with.....Simple to unhook the shaft and avoid any possibility of more problems.....

[arveetek]

I am not sure on towing that rig with the Tcase in N

GM allows flat towing 4WD vehicles with the transmission in Park and the transfer case in neutral. Popular for RVer's to tow 4WD trucks behind their motorhomes for that reason.

Casey

[Robyn]

Good deal.......
I have heard of issues....But not specific to the GM Rigs...

Most common T Cases have an oil pump driven off the rear output shaft that feeds all the internals.....

[DickWells]

Just jumping in to let you know that I appreciate everyone helping. And, to admit that I haven't touched the Burb for nearly 2 weeks. With the mild Winter we're having, being unusually dry, the attraction of making grocery and doctor runs with the Miata, is just too tempting. Rough roads have proven to be not even an annoyance for that car. It's the only car (out of nearly 40), that I've ever owned that doesn't rattle! I've been amazed, that I could drive into a car wash, wash the thing, even letting the high pressure wash and rinse get very near the window/top junction and get back in, and not find a drop of water, inside, except that which was on my shoes! A fantastic automobile. Of course, it just turn 21 K miles, which, for a 2016 car, is pretty low. In 22, I put less than 600 miles on it.
Gotta get "on-the-stick, and do some checking on the 4L80. I'll try to stay in touch, more diligently.

[DickWells]

Okay! Turns out, since I had no problems going in and out of reverse and neutral, that I simply backed the Burb onto our flatbed trailer and delivered it to Bill's. Pushed it off the FB in neutral and Bill fired it up. Went into all positions just fine! Anyhow, they had the car a couple of days and found that the speed sensor in the T-case was wired wrong. So, $275, later, I picked it up and it drives just like it did, before, which was fine, except the 1-2 shift is still very firm and, the noise that I talked about is still there. So- - - after a grocery run, yesterday, I left it idling, got under the hood and find (pretty sure) that the turbo is where the noise is coming from. I believe that what is happening is, that the sound is telescoping down the exhaust pipe and that's why I thought the sound was coming from the gearbox, weeks ago.
Now, I also believe that the aggressive 1-2 shift is my own fault, because I have programmed the shift points - lockup rpms wrong, which can, of course be changed, right from the driver's seat, on the Shift4 screen.
Since Bill removed the tranny and sent it out for rebuild, almost two years ago, I'm not at all sure that it was "yours-truly" that wired that speed sensor incorrectly, when the rebuild was completed. Years before, when I installed the Shift 4, I spent an awful lot of time, checking and rechecking my connections. Guess we'll never know.
Right now, I'm gonna go out and remove the big turbo hose and do some checking. But, based on what I heard and felt, yesterday, I'm thinking I need to put a kit in the turbo. Any thoughts/advice?

[a5150nut]

Don't leave any loose rags anywhere under the hood while running with hose off turbo.

[Robyn]

Rags have been known to get sucked into turbo's......It's UGLY....

[DickWells]

The turbo is glassy smooth, when turned by hand and I can't feel any play, either laterally, or thrust. With 15-40 Castrol in there, I didn't expect it to spin "like a top" with cold oil, and it didn't.
I need to get under there and check the exhaust system. Right now, the only thing I know for certain, concerning the noise is, it's louder than it was a few weeks ago.
So, for turbo experts: What are the chances of a very smooth-turning turbo, with no discernable play, being bad? Bear in mind that the noise I hear is not as loud as the the diesel rattle from the 6.5.

[Robyn]

Grab a good heavy glove.....With the engine running...WARM...Place your gloved hand on the sheet metal shield on the turbo and see if this makes a difference in the noise......

I have seen these shields radiate a metric buttload of noise...
Easy to fix....Bolt on a strip of 1/4" flat lead to deaden the noise....

The injectors and the regular diesel rattle gets picked up and radiated by the shield.

My bet is a firm gloved hand on the heat shield will kill the noise....

[DickWells]

Thanks, Robin. Will do that, tomorrow.