4l80e

Status
Not open for further replies.
Joined
May 28, 2017
Messages
49
Location
Missouri
Ok guys I’m back again. Lol. I think I may have finally solved my problem but wanted some advice before I started tearing things apart. So my 99 burb k2500 7.4l with 4l80e trans started losing reverse one day, it was slow to engage, then the next day it was completely gone, no feeling whatsoever of it engaging. Then 4 or 5 days later I went to take a short trip to the auto parts store and it was like my truck was locked in 4wd low and had a very very noticeable delayed shift from 1-2. So I turned right around and parked it and have been researching the cause ever since. That was about a month ago and I think I may have finally found out what the source of my issue is. I’ve been reading a lot about my components and I think it’s the torque converter that is causing my problems. Back in late summer I had an issue with it feeling like I was driving over tiny speed bumps, something I now find out to be converter shudder, something back then I thought to be transfer case issues, I pulled the front drive shaft and my problems seemed to go away, until a few weeks later when reverse started going out. I don’t drive the truck much so maybe that’s why it seemed to take so long for it all to come to this conclusion and for me to put all of the symptoms together but I think that’s what it is. Any and all feedback would be appreciated. Especially so from mr Clinebarger, if he would be so kind as to chime in. Lol. You were a great help to me before thank you. I think my tcase needs a new motor as it still switches from 2wd to 4wd on the switch on its own but I can’t get it to switch from 4wd to 2wd by pressing the button. I can hear it trying to switch, and I can feel it, as it makes the vehicle lurch when doing so but it will not engage 2wd when I press the button. I think it needs a new switch(button) as well as the motor. Hopefully not a new or rebuilt tcase. This 4l80e was bought used and installed by yours truly so I may have screwed up somewhere as it was my first ever tranny swap, sounds like it won’t be the last time I pull a tranny if it is truly the TC acting up. Oh, I replaced solenoid A and B and the fluid was already quite dirty in the pan after less than 5000 miles of use. No metal pieces but quite a bit of “mud”. I cleaned the pan and the magnet and topped it off with Dex VI after replacing the solenoids but no change. That was my first and cheapest repair option and a chance to inspect the valve body and the pan. I didn’t replace the filter because it was new when I installed the trans. Any help? Ideas? Anything besides R&R? I’ve still got the original bad 4l80e that was the reason for all of this starting last winter. If nothing else, I’ll take it to the shop and have it rebuilt to clinebarger specs and reinstall it myself. That should cut the bill in half at least I would guess. Thanks in advance everyone
 
How many miles?

Sure sounds like you are going to have it rebuilt. Converter shudder is not a big deal depending on how much and when it occurs.
Sounds to me like you are losing line pressure, perhaps you have a bad pump or it just worn out.
 
***update***
So, after posting the original post I got to thinking, that’s not always a good thing lol, I went outside and put the 4wd fuse back in and reverse tried to engage but there was a grinding noise, like when you try to put a manual in gear but don’t have the clutch fully depressed. So I put it back in park but the grinding noise stayed so I shut the truck off and restarted it and the noise went away but then it wouldn’t try to engage reverse again. But no grinding noise this time when shifting to reverse. Now I’m confused again. The noise is coming from the firewall area so I assume it’s the TC making the noise but why would me putting that fuse back in have anything to do with the TC? I didn’t try to drive it to see if the issue with the delayed shifts was still present, I wanted to wait for your input. Thanks again in advance for any and all help
 
Shudder isn’t a big deal probably to most but it sure felt like the truck was going to come apart the couple times that it happened. It was as if the truck was driving one wheel at a time, like the wheels were stepping instead of rolling. Lol. It spooked me pretty good cuz when it happened I had just gotten on the interstate a couple days after having a wheel literally come off of the thing. But that was due to my laziness and not rechecking the torque on the lugnuts on the wheel spacers. Luckily it happened as I was backing out of my driveway and not on the interstate at 85 mph. Smh. I’m at a loss now and am back to thinking it’s something electrical since reverse engaged when I put the 4wd fuse back in. Help!!!! Lol
 
Do you have any codes?

Based off what you have told me about your fluid change and looking at your 35 inch tires I am still going with rebuild time.
 
There may be some codes but I haven’t chanced driving it to the auto parts store to get them. The CEL isn’t lit because it was always lit because the truck doesn’t have any cats so I removed the offending bulb. Lol. Wanting to get cats put back on it though to fix that problem. The cats were removed when I bought it. The service 4wd light is on until I put the fuse for the 4wd back in and then it goes out. Did you see the update?
 
I know I’ll have to pull it if it’s the TC but I’m hoping the tranny is still ok in that case and a new converter will fix the problem. But now I’m not sure if anything again after the update to my post. Smh
 
Ah forget it. I’ll just have the one I’ve got sitting in the garage rebuilt. Any recommendations on a TC? I was going to rebuild it myself but who am I kidding, I’ll never have the time for it. I’ll just have to hope the trans shop will do what I ask them to do as far as mods go. I should probably buy the parts for the mods and take them to them with the trans though I would think don’t you? As far as the extra drilled holes and whatnot I’ll just have to hope they do it. Or tear the thing down once I get it home to make sure. Man I’m at a crossroads here. Lol
 
I had a 4L60E computer go bad and not give the signal to raise the line pressure. If you rebuild the trans, get a new computer as well.
You will have to have it flashed by a dealer.
 
You can ride on the exception to this rule for a long time, but the rule still stands: spend money to keep it in good shape, a (proper) repair or two at a time, or spend more money when all the band-aids or budget fixes come to a head at once.

You can get by removing bulbs, installing well-used transmissions, and making it look
big and bad before it's mechanically sound... until you can't.

I put a reman 4L80E from Street Smart transmission in a 1500HD 2 years ago and it's still working perfect 50K and a lot of abuse later. I'd look them up online and get a quote. Good shipping and warranty.
 
Last edited:
I have a 97 K2500, 454 4x4 with 4l80e trans. Although it is a beater due to the paint problems, I do not have problems with the trans, other than this: if it sits for a very long time, it seems to be slow to go into gear the first time, regardless of D or R. It seems to take like 2-4 seconds to go into gear the first time. After that its fine.

Right now its sitting due to a blown front brake line that I will repair eventually. Not sure what I am going to do with it long term.
 
I see you haven't checked the codes, and it could certainly be an electrical problem. At least make sure the connectors on the trans are tight, especially the big one on the passenger side.
 
What Alex V said is the truth. I currently have an 09 Suburban with a 6L80E in it that I have taken stellar care of since day one.
Trans gets serviced on regular intervals and I added a cooler since I take long trips. Transmission has given me zero problems in 140,000 miles.
I figure when it finally starts giving me grief, spending 3500 on a new one with new solenoids and everything won't seem so bad.
 
I was actually looking at one of them believe it or not. Their prices are actually cheaper than everyone else online and by the time I buy all of the necessary parts for the modded rebuild I’d like to do id almost be in for the amount of a monster trans anyway. Only thing is that it won’t have the mods that I want done to it but a working trans would be so much nicer to start with than the two broken ones that I have. Lol
 
There is no big one on the passenger side. The large case connector harness is on the drivers side between input and output speed sensors. I’m thinking it’s something electrical and I’m about to chance driving it to the auto parts store to find out what the codes are. Lol. I’m fed up with the guessing game and ready to get my beloved Burb back on the road
 
Trust me, I know only too well about putting up the cash to keep things operational. Have you ever seen the movie “The Money Pit”? Lol. I bought this truck less than 2 years ago for just under $6k, I’d have to actually sit down and do the math but rough guesstimate, I’ve got almost double that in it in repairs, maintenance and upgrades. Rebuilding this 4l80e and the motor, reinstalling the cats and redoing a lot of the wiring are on my list for spring 2018. Luckily, this isn’t my daily driver so it doesn’t hurt too bad not to be able to drive it, except, it is my favorite to drive. Smh
 
Status
Not open for further replies.
Back
Top