FSC - Chevy Truck Forum

Thread: 4L60E Slips out of 4th

Page 1 of 3 123 LastLast
Results 1 to 20 of 57
  1. #1
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    4L60E Slips out of 4th

    OK, I tried searching for some help, but I was unable to find anything that really matched my symptoms. So, here goes on my first post here:

    I am a Ford guy,which is why I am not sure where to troubleshoot this trans, but I got a great deal last year and bought a 98 Z71 that was in excellent condition with 199K on the clock, original everything. Just couldn't pass up a shot at this perfect hunting truck. Once I got it, I changed all the fluids and filters to ensure that a regular maintenance interval was started. The transmission looked really good too, with just the typical buildup on the magnet at the bottom of the pan... no specks of bronze or chunks of clutches, and the old fluid looked to be in good shape with a dark red color and no burnt smell. I have since put 15K miles on it, and the trans fluid is at the proper level and is still a good, bright red color at 215K on the clock.

    Recently, when the summer heat came, the trans will slip out of 4th and downshift into 3rd when I am going 65 MPH or faster. It only does this when the truck has been driven for about half an hour or more during high temps, so everything is good and heatsoaked at normal operating temps, and OD works perfectly at 45, 50, and 55 MPH. The slip always occurs when you release some of the load on the engine, eg going down a bridge at part throttle cruise, but it will also do this sometimes on level ground as well. Part throttle release or lifting completely off the gas is the usual trigger, although when it's really hot outside the trans will slip on level ground without moving the throttle. But, after slipping and stabilizing in 3rd gear in all cases, it will again upshift into 4th. When it's really hot outside, the process of slipping repeats itself at about a 20 second interval, regardless of throttle position.

    I am confident that it is not simply the TC locking and unlocking, since when it downshifts, I have manually shifted into 3rd, and the RPMs stay where they were, even when I change throttle position. This is certainly a locked TC. Every time the trans shifts, even when it slips in and out of 4th and back, it is smooth and all other trans operations seem normal (other than the slip when it's hot). I know the temperature is a factor in all this, since the trucks OD works perfectly at night

    Any suggestions what it could be?

    Thanks,

    Pete
    Last edited by big pete; 06-14-2010 at 09:13 PM.

  2. #2
    Registered User Randy_W's Avatar
    Join Date
    Oct 2006
    Location
    Salisbury, MD
    Age
    64
    Posts
    455
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    I hate to be the bearer of bad news but that's a symptom of catastrophic failure, it's about to break the sun shell and/or many other parts. I would stop driving it right now and get a quality rebuild with the now considered "standard" upgrades including the Transgo shift kit. I know we'd all like to think it's some simple thing but that symptom is almost always followed by a BANG and no go.
    RandyW
    '02 Short Bed/ Reg Cab/ LS1/SS wheels,3.73 Gears

    '96 Tahoe 2dr 4x4


  3. #3
    FSC's french Canadian shane_k1500's Avatar
    Join Date
    Apr 2008
    Location
    CANADA! LE NORD BLANC!
    Posts
    2,086
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Quote Originally Posted by Randy_W View Post
    I know we'd all like to think it's some simple thing but that symptom is almost always followed by a BANG and no go.
    he's absolutely right , take it from me


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

  4. #4
    Registered User bigtfw2000420's Avatar
    Join Date
    Oct 2005
    Location
    south tx
    Age
    32
    Posts
    1,642
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    something bad is about to happen


    :fsg: 98 k1500 5.7 Magnaflow exhaust BBK 80 mm throttle body AEM brute force CAI nelson performance tune 93 octane RC 6" 285/70/17 BFG KM2 4 14 bolt sf disk brakes 4l60e fully built

  5. #5
    Registered User knightrider955's Avatar
    Join Date
    Nov 2009
    Location
    Lakeview, MI
    Posts
    83
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    It is NOT your sunshell gear going bad. Sunshells dont start getting bad, they flat out break and have nothing to do with the tranny shifting on you. However, timing will cause that. My Yukon did the same thing, I turned the distributer counter clockwise just a touch and it fixed it. The vortec 350's are known for the ditributer gears wearing out. Turning the distributer is a temporary fix. You need to change the gear and then you will have a permanent fix. I ordered a nice aluminum distributer with the gear and new cap off ebay for 60 bucks.
    97 GMC Yukon. True Duals, Hypertech, 99 Tranny. Punished religiously

  6. #6
    Old Man Mountain Swaggerwagon's Avatar
    Join Date
    Sep 2009
    Location
    Tennessee
    Age
    45
    Posts
    716
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Quote Originally Posted by knightrider955 View Post
    It is NOT your sunshell gear going bad. Sunshells dont start getting bad, they flat out break and have nothing to do with the tranny shifting on you. However, timing will cause that. My Yukon did the same thing, I turned the distributer counter clockwise just a touch and it fixed it. The vortec 350's are known for the ditributer gears wearing out. Turning the distributer is a temporary fix. You need to change the gear and then you will have a permanent fix. I ordered a nice aluminum distributer with the gear and new cap off ebay for 60 bucks.
    Ok, then explain how the OP's trans shifts/stays in OD just fine at night?

    A bad dizzy gear is always bad, not just in the heat of the day.......

    Personally, i think the transmission is on it's way out...mine started slipping out of OD constantly before it went out..

  7. #7
    Registered User knightrider955's Avatar
    Join Date
    Nov 2009
    Location
    Lakeview, MI
    Posts
    83
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Quote Originally Posted by Swaggerwagon View Post
    Ok, then explain how the OP's trans shifts/stays in OD just fine at night?

    A bad dizzy gear is always bad, not just in the heat of the day.......

    Personally, i think the transmission is on it's way out...mine started slipping out of OD constantly before it went out..
    Ok no problem. My Yukon did it only in the day too and was fine at night. The computer adjusts the timing different in cooler temps and warmer temps. At cooler temps my Yukon timing was still in spec enough to run ok even with play in the dizzy gear but when it was warm during the day it was so far out that it would even buck a little bit after it shifted out of 4th. And just like Big Pete said, mine would shift out of fourth when letting up on the throttle slightly or everytime I was going down a slight hill. But under medium to heavy throttle like driving up hill or accelerating it was fine. I guarentee its your dizzy gear pete. Turn the distributer ever so slightly clockwise and it WILL run good for now. But get the gear changed. I guarentee that gear is knife edged from wear.
    97 GMC Yukon. True Duals, Hypertech, 99 Tranny. Punished religiously

  8. #8
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    It wouldn't surprise me if the gear at the bottom of the distributor was bad. Here's why...

    When I bought the truck last February, the owner thought that it needed a complete rebuild because the engine hesitated and the trans shifted harshly. So, I bought the truck anyway, since I didn't think mechanical problems were the issue (no leaks, burning of fluids, grinding sounds, etc). The "service engine soon" light was on and was a pretty good hint that the issues were electronic, not mechanical.

    Turns out, it was throwing a code for a faulty cam sensor. I went to replace the sensor, only to find that the original one wasn't even plugged in. After finding the connector that was dangling and plugging it into the sensor, it threw a different code. This time, it said that the cam sensor wasn't agreeing with the crank sensor. I rotated the distributor about 20 degrees CCW to make the timing work, and things were fine ever sense. I also changed the badly worn plugs and wires though, just to make sure. Truck still gets 17 MPG @ 65 MPH, has great compression and runs strong -- as long as the trans isn't heatsoaked.

    Seeing that the distributor was a good 20 deg off, and the cam position sensor wasn't plugged in at all, it wouldn't surprise me if the the previous owner was attempting to replace the distributor gear since it seems to be a commonly worn out item on these engines. While attempting to do that though, he failed to install everything correctly and made problems with the truck worse.

    I will pull the distributor and check on that gear soon.

    Pete

  9. #9
    Registered User knightrider955's Avatar
    Join Date
    Nov 2009
    Location
    Lakeview, MI
    Posts
    83
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Yes check the gear, if it looks ok then the previous owner probably changed it and never hooked everything back up right, just like you said. If the gear is ok, then take it in and get it timed. These vortecs can only be plus or minus 2 degrees on timing or they wont run right. The only way to time it right is with a scanner.
    97 GMC Yukon. True Duals, Hypertech, 99 Tranny. Punished religiously

  10. #10
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Yeah, when I turned the distributor that ~20 deg, the shop on base had a Snap-On Solus scanner and we set it to 0 deg. I have since moved though, and don't have access to a scanner that can read cam retard... just got off the phone with the auto hobby shop on base before I yanked it.

    Damnable....

    As soon as I find that scanner, I will pull it.

    Pete

  11. #11
    Hnic at transbuilderguy
    Join Date
    May 2010
    Location
    Gainesville, FL
    Age
    41
    Posts
    1,727
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    sounds to me that the servo seals are leaking at this point you could probably put new seals in it and it will cure the problem with the higher heat the fluid gets thinner therfore bypassing the seals that are hardened, change the seals on the servos this can be done in the vehicle dependoing on band condition it may help you prolong the life of your trans but I would say for you to use this time wisley
    Master certified tech since 2005
    check out my customers group
    https://www.facebook.com/groups/1467725086801418/
    904-402-6016

  12. #12
    Registered User
    Join Date
    Sep 2009
    Location
    Maine
    Posts
    1,737
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    It will be interesting to see how this unfolds. Assuming the new dist gear and resetting the timing takes care of it, I would suggest some maintenance on the trans. A Superior shift improver is a great idea. This one will tighten up the shifting, and modify the converter to a full lockup, eliminating the variable TCC strategy.

    http://www.superior-transmission.com...Page.cfm?ID=12

    I would also change ALL the trans fluid to a high quality synthetic fluid such as Mobil or Amsoil. There are a few posts here that detail how to safely exchange the fluid in your trans.

  13. #13
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Yeah, my instinct said that it would be a bad solenoid, but I couldn't figure out how the Chevy layout worked, since it doesn't use a solenoid for 4th and instead uses a combination of other solenoids. Is the servo that one round port on the right hand side of the trans, or are the others in the valvebody that inside the pan?

    Also, when I swapped the trans fluid last year, I did use Mobil 1 Syn and didn't have these issues last summer in 110 deg heat. Something has worn or changed since then.

    Pete

  14. #14
    Registered User Randy_W's Avatar
    Join Date
    Oct 2006
    Location
    Salisbury, MD
    Age
    64
    Posts
    455
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Sun shells do crack and cause problems before they fail, mine did. However, that's not what I said, I said the tranny is probably going to fail including the sun shell possibly. Mine did just that.

    Set the timing, replace the servos, then get your money ready to rebuild the tranny, it's getting ready to fail.
    RandyW
    '02 Short Bed/ Reg Cab/ LS1/SS wheels,3.73 Gears

    '96 Tahoe 2dr 4x4


  15. #15
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th



    Got the trans on video today on the way home from work. Starts in 4th at 72 MPH @ 1800 RPM, then smoothly slips into 3rd at 2600 RPM, and back smoothly to 1800 RPM. Cruise control was on to hold the speed while filming. This happened while cresting a bridge and heading back downhill.

    Still no luck on finding a scanner to help reinstall the dist...

    Pete
    Last edited by big pete; 06-16-2010 at 03:35 PM.

  16. #16
    From Mini to Fullsize.... Hotwheelz's Avatar
    Join Date
    Oct 2005
    Location
    Jasper, Indiana
    Age
    34
    Posts
    1,550
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    it does sound like your servo seals are leaking. and causing your 2-4 band to release. then the pcm sees that your road speed calls for 4th and re-applies the band. you can do servo seals so cheap and your problem will more than likely be gone. have any friends with a pressure gauge? see what line pressure is doing. I bet you it's bleeding off. that 2-4 servo seal is such a simple job man. if you get that seal replaced, i see no reason why your transmission is in danger. right now though you are wearing out that 2-4 band, because it is slipping 4th gear. im surprised you aren't getting a gear ratio error code yet. get that servo seal kit from the dealership for like 20 bucks man.

    why are you guys telling him is trans is getting ready to fail?
    Last edited by Hotwheelz; 06-16-2010 at 04:46 PM.
    2009 GMC SIERRA | SLAMMED 5/7 | 22" BOSS 330'S | ASE MASTER CERTIFIED

  17. #17
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Cool deal, Wheelz. Where are the servos located? Are they in the valvebody, inside the pan, or under this round cover looking thing on the passenger side of the trans? This truck is my first Bowtie, pretty unfamiliar with the 4L60...

    When the trans starts to slip like that, I just lock out OD by selecting 3rd and leaving it there. I'm willing to give up a couple MPG and MPH to keep the trans from constantly locking and unlocking the converter and shifting, making all that heat. Heat's the last thing the trans needs this time of year.

    Pete

  18. #18
    Hnic at transbuilderguy
    Join Date
    May 2010
    Location
    Gainesville, FL
    Age
    41
    Posts
    1,727
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Quote Originally Posted by Hotwheelz View Post
    it does sound like your servo seals are leaking. and causing your 2-4 band to release. then the pcm sees that your road speed calls for 4th and re-applies the band. you can do servo seals so cheap and your problem will more than likely be gone. have any friends with a pressure gauge? see what line pressure is doing. I bet you it's bleeding off. that 2-4 servo seal is such a simple job man. if you get that seal replaced, i see no reason why your transmission is in danger. right now though you are wearing out that 2-4 band, because it is slipping 4th gear. im surprised you aren't getting a gear ratio error code yet. get that servo seal kit from the dealership for like 20 bucks man.

    why are you guys telling him is trans is getting ready to fail?
    hey lol I told him the same thing lol and to just save money in case
    Master certified tech since 2005
    check out my customers group
    https://www.facebook.com/groups/1467725086801418/
    904-402-6016

  19. #19
    From Mini to Fullsize.... Hotwheelz's Avatar
    Join Date
    Oct 2005
    Location
    Jasper, Indiana
    Age
    34
    Posts
    1,550
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    yup its the round thing on the side of your trans. i'll try to remember to get you some instructions on how to do it tomorrow at work. feel free to send me a txt and remind me. 618 334 7751 i work for jasper engines and transmissions, so i have access to some good tech info.
    2009 GMC SIERRA | SLAMMED 5/7 | 22" BOSS 330'S | ASE MASTER CERTIFIED

  20. #20
    Registered User
    Join Date
    Feb 2010
    Location
    Abilene, TX
    Posts
    21
    My Feedback

    (0% Positive Feedback)

    Re: 4L60E Slips out of 4th

    Thanks, man. I actually found some videos on youtube, showing step by step how to tear down the servo. Pretty straight forward like everybody said, but I would appreciate whatever tech info you could round up from work. Turning down good info is never something good!

    Pete

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •