NikoKourm

Before I get started, I want to say I am aware that there are probably millions of threads like this one after people do rebuilds, but here I go.

Here's a lot of backstory, you can probably skip this:
So, I shared a 2004 Chevy Silverado 1500 LS with my older brother for some time now. Every time something went wrong, he would tell me something went wrong and I would have to figure out how to fix it. Ever since we got the truck, I've noticed that there was some leakage coming from the connection between the transmission and the transfer case. Over the summer, I noticed that there was an awful starting to arise when it drove over 40 mph. My first thought was that I had to do with this connection, so I took it upon myself to take out the driveshafts and look at the transfer case. I opened the transfer case, I replaced a part (the piece that over time will wear into the case and cause a hole) with a better one, put it back together and put it on the truck with a new gasket. (The noise was still there and it turns out it was the U-joints and the old rear and front pinion yokes, so I replaced all those.)

Here's where the backstory gets important:
When I did this job, I figured I was going to have to drain the transmission before I took the transfer case off because I thought it would spill out from the back. I was utterly wrong about that, but I did it anyways. I opened up the pan, drained as much as I could and replaced the filter/seal/gasket. Now I might've done the damage here already by doing that, but When we were putting everything back together, my brother and I were filling up the transmission through the dipstick. I recall telling him that he would need to refill the transmission after driving it because it wasn't going to be at the proper level. It's the end of the summer, I go back to college and he's driving it day in and day out.

Come late October, he's complaining the truck isn't shifting right. There's been a huge puddle of dried fluid on front driveway that was only getting bigger as time progressed, so the fluid level was dropping gradually. I didn't know whether or not he actually did what I told him to do, so I assumed the best and said I didn't know. Come early November, he comes up to me and tells me it's not reversing anymore. I see him the next day finally filling up the transmission with the small bottle I left exactly for that purpose, I was pissed at this point. I wait a week, my dad has taken it for a spin and said it wasn't shifting out of 2nd. I was trying to go to Home Depot one night, I took it for a drive and I couldn't get down the road without the engine revving up like it was in neutral after getting out of 2nd. I was pissed and I knew this meant two things: have the transmission rebuilt or the truck was gone.

When I drained the fluid, which was all burnt and black (and smelled awful), I noticed I only drained out about 4 quarts. Originally I had taken out at least 6 or 7 and put back in 5. So my brother never filled it up and as it was never filled up, it kept draining out through the leak.

Here's where I get to the transmission rebuild
So come winter break in late December, I can finally start doing the rebuild. I was following a series on YouTube called "4L60E Rebuild" by TransmissionBench and I had done plenty of research on how to do things. I bought a Pioneer brand rebuild kit to do the job and I bought all new solenoids and electrical components. I took everything apart (everything was covered in thick black burnt transmission fluid) and cleaned everything as I went along. I noticed when I went to the rear, the last piston in the very back of the case had a crack on the side. I replaced this aluminum piston along with the seals when I did the rebuild.

Here is where I got iffy on the rebuild. When I was taking apart and putting back together the input drum, the 3-4 clutch pack was completely burned out. In the spot that they sat, I noticed there was some wear on the inside of the input drum. I was going to purchase a brand new one, but my other brother told me it wouldn't be necessary. I also took apart the forward sprag for cleaning purposes and I am almost 95% sure it was put back together properly and in the right orientation when I placed it in the case, but this could likely be my ailment now. I replaced the green O-ring, all the pistons, all the clutches/frictions inside the input drum and everywhere else in the case. I even replaced the spring cages on the sides with brand new ones (the old ones were really bad). I watched the videos over and over triple checking everything 3x over as I was going along. The guy in the video said it wouldn't be necessary to replaced the Teflon rings on the shaft if they were spinning freely and not loose. So I did not replace those or the ones on the front pump.

Now back to the valve body. Like I wrote before, I bought all new solenoids (NAPA shift solenoids, the rest were ACDelco) and electrical components and I replaced everything, including the wiring harness (also ACDelco), new separator plate (TransGo) and new accumulator pistons. I put everything back together, put it back on the truck, filled up the fluids and I was on my way. I take it for a drive, 1-2 and... no 3-4. I was pissed.

I know it's unlikely, but could the computer be throwing a tantrum because of the new electronics? When I drive it, it does the same thing it was doing before when I knew the clutch pack, but before it was throwing a check engine light. I figured this meant the shift solenoids were bad, but I knew from the black fluid that they weren't the only problem. I've had the battery unplugged for some time, so everything reset. (I know it's not the battery connection, because actually the positive connector was so covered in oxidation, the truck didn't start on me two days ago.)

I brought it to the dealership specifically for the computer reboot and the guy wasn't going to do it for me because he was adamant (and I'm sure he was right) that the something was up in the input drum (all the problems I listed, he said the same). I know that he was just trying to get me to tell him to put it up on the jacks so they could "look at it," A.K.A. take it apart on me and charge me for ten hours of labor (which I do not have the money for).

I just want to know if there any other potential problems I can address outside of the truck before I take everything apart again and bring the transmission back into the garage. My oldest brother borrowed his friend's computer scanner and he said he'd mess around with that throughout the week.

Here is a list of what I think could be wrong:
- New electronics mean the computer is acting bad
- Battery connection
- I heard online that a bad fuse could also be my ailment, but it's unlikely
- Also unlikely, but a bad servo
- Although I know for sure (100%) that the check ***** are in place, check ***** could not be in the right spots
- The Teflon rings (I tested them and everything seemed to check out okay)
- The input drum (slight wear where the 3-4 clutch pack sat)
- Last but not least, the wretched forward sprag

I am willing to take it apart again, as cold as the weather may be and as annoying it is to not have it work out like I wanted it to. I was upset for an hour after the dealership, but I got a new sense of determination to go back and do it all over.

The good news is, once I got everything back together and took it for a spin, there was no more leak (over this past week). So at least I solved that never-ending problem.

Here are a few pictures of the tear-down:

mrvedit

If the current problem is that the engine revs freely after the shift into 3rd, then it is almost certain that the 3/4 clutch is gone again. Very likely there is a leak in the 3/4 apply circuit which you missed.

To answer some of your other thoughts:
* A bad forward sprag has different symptoms
* A bad servo affects only 2nd and 4th gear
* This is not a computer problem; new parts affect it
* Missing checks ***** give abrupt shifts, not missing gears

I would always suggest replacing the teflon rings as old one are easily damaged on assembly.
A loose input shaft in the input drum can cause a leak leading to clutch failure.
Did you check the 3rd accumulator check ball at the back of the servo area?

I always suggest connecting a trans pressure gauge after a rebuild to make sure the pressure under acceleration (even just blipping the throttle) is high enough (e.g. 200 psi) to prevent premature clutch failure.

Please summarize the exact symptoms before we go on.

mrvedit

Forgot to mention:

One way to test the 3/4 clutch is to disconnect the electric trans connector as that forces "limp mode" which is 3rd gear, with the shifter in OD. While acceleration is slow at first, if you cannot get the car up to speed with brisk acceleration after e.g. 30 MPH, the the 3/4 is slipping and shot. In limp mode the trans is also in max line pressure mode.

On Gen 4 cars it is very difficult to disconnect/unplug the trans connector, but on most trucks and SUVs it should be relatively easy.

NikoKourm

Would the 3-4 clutch really burn out that quickly? As soon as I took it for a spin after putting it back together, it was doing this right away (this was last weekend). I drove it, 1-2 was fine as always, but where it would normally shift into 3rd, you could feel the truck just lose any forward momentum and the RPM gauge would just rise up. If I put it into 3rd gear, it will just rev up exactly like that. I can get up to 40mph in 2nd (although that's not good because the engine is working much harder than it should).

As for the 3rd accumulator check ball, yes I checked that one. As far as the video went, it was fine. I used 50/50 transmission fluid/mineral spirits and checked to see if there was leaking into the case, nothing from what I remember.

And for that connector, do you mean the green circular connector on the servo side of the case? I could potentially have someone try that at some point this week.

NikoKourm

How about the low fluid level, what would that have caused in terms of deteriorating and destroying components of the transmission? I know that too little or too much can cause problems, so what would overheating due to too little fluid do?

I am just asking because I am wondering if there's anything else I can look into, maybe the valve body/booster sleeves are crap and I just didn't know.

performabuilt

iTrader: (25)

One thing I notice while it would not cause immediate failure You do need to replace the springs or the spring cage assemblies the spring do nothing as they appear in photo.

Another thing to check is the input shaft to drum area, After assembly air check 3-4 clutch and make sure you don't have air coming up around the shaft I have seen some pretty substantial leaks there. Make sure also the orifice cup plug has not popped out of the drum its right at from with shaft this will cause immediate failure.
Another issue that will cause immediate 3-4 failure is if you damaged the thin green ORING in the drum it will allow the forward oil to vent into the 3-4 clutch piston causing partial apply in 1-2 gears quickly frying the 3-4 set.
Also a bad pump stator make sure it does not have grooves worn where the shaft rings ride on the inside of the stator does not take much if you can feel it at all its to much.

Last make sure the 3-4 return springs are on to of the 3-4 apply shell without them the 3-4 clutch will stay partially applied all the time even idling from cross leaks that always exist

Hope this helps some

NikoKourm

Thanks for the reply.

I did replace those five little spring assemblies when I was doing the rebuild, but maybe I didn't something right in the 3-4 apply area.

How could I tell that the green O-ring was damaged/prevent it from getting damaged again if I do reassemble and replace everything. Are there any tests I can take to know for sure nothing has been destroyed inside the input drum upon reassembly? I know I can do pressurized air along the shaft for applying the different clutches.

Again, I am still skeptical of that wear on the sides of the input drum. Would it be possible that that could be the reason for the slippage of the 3-4 clutch instead of the springs not applying right?

I was thinking if (and probably when) I do take it apart again, I would just bring the input drum into a shop/dealership and have them make sure it's working properly.

Thank you.

mrvedit

I didn't see anything in your input drum pictures that are a concern.
However as PerformaBuilt explained (and I briefly mentioned), the area where the shaft is pressed into the input drum can often leak. One pro builder tested and found that about half of used input drums leak in this area. His solution was to always pull the input shaft off, coat the area with Red Loctite and press it back on.
An additional solution is to install the Sonnax Input Drum reinforcement kit:

http://www.sonnax.com/parts/3600-inp...nforcement-kit

Note that these "fixes" require a hydraulic press. I just use my $120 HF 12-Ton press.
A trans shop can do this for you. I wouldn't count on a dealer doing anything other than replacing everything.

Again, if you take it apart again, get the teflon rings replaced. It is trivial for a trans shop with the right tools. As mentioned, carefully check the inside of the stator shaft, where the rings run, for any roughness. Perhaps let a shop check it for you, and replace it if needed.

Pressure testing the input drum is two parts:
1. Test just the drum, apply the air hose rubber tip to the holes in the input shaft.
There should be very little leakage if you hold the bleed hole shut with your finger.
2. Next, insert the input drum into the pump and use a stiff cardboard box (4x4x6") or other jig to support the assembly with the shaft straight down. You can then air test the input drum using the holes in the pump. There is more leakage this way, but the clutches should still apply. This also tests the teflon rings.

As for worrying about your boost valve, etc, I always recommend hooking up a Trans Pressure Gauge (ATD-5550 on Amazon for $35) both BEFORE and AFTER rebuilding the trans. While idle might be as low as 50 psi, just blipping the throttle should shoot the pressure to around 200 psi. And Reverse is around 150 psi.
If the pressure is low before you rebuild, it gives you something to concentrate on.
And then of course check the pressure after the rebuild to be sure the trans is safe to operate.
Note that bad engine sensors (TPS, MAF) can result in low pressure; so be sure to check for codes too.

I found it interesting that PerformaBuild recommended replacing the five 3-4 return springs. I always use them, but many builders say to leave them out. Even the ATSG manual says to leave them out. They only reduce the pressure on the 3/4 clutch by about 1%, but as mentioned keep the frictions from wearing a bit while in 1st and 2nd gear.

NikoKourm

Okay, I will definitely keep these things into consideration when I take it apart again. Thanks for the tips.

98CayenneT/A

I left them out of mine......

bbond105

I attached some instructions from Sonnax that shows how to air test the input drum and valves in pump. Air testing is on the last pages. Actually the is a lot of good info in all of the instructions.

performabuilt

iTrader: (25)

[/QUOTE]I found it interesting that PerformaBuild recommended replacing the five 3-4 return springs. I always use them, but many builders say to leave them out. Even the ATSG manual says to leave them out. They only reduce the pressure on the 3/4 clutch by about 1%, but as mentioned keep the frictions from wearing a bit while in 1st and 2nd gear.[/QUOTE]

Yes we keep them but replace the springs in each keeps the weight of the apply/pressure plates from weighting the clutch pack making heat even when just idling another interesting note i have found not part of the OP issue is the apply and backing plates not being true even new, We for a long while now have been machining each of these I was looking a some cores and some we had out that were back for restores/refresh and noticed just a slight irregularity in these plates will result in a slight burn mark in the same position on each steel and this of course also means more burn for the 3-4 frictions. Since we began doing this some while back like i said even with new plates we have not seen any of these spots Just interesting tidbit.

NikoKourm

So, I started my truck today after prepping my work space for tearing down the transmission and it finally throws a check engine light.

Now I know this could mean anything, but when the 3-4 clutch, the truck was throwing a check engine light. At that time, the scanner we had wouldn't read the code and would act like the computer isn't registering. I know it's not the scanner because it's ready bad O2 sensor codes, bad MAF codes and other codes on this truck and it has worked on all of our other vehicles.

So today, I plug in the scanner because it's throwing the check engine light again. And again, the scanner is not reading the computer or registering that it's there? Could it mean, perhaps that something electrical went wrong in the transmission?

I have a better computer meant for more advanced scanning, but my brother currently has it with him. I'm definitely going to check it out with that one once he's available.

mrvedit

Your scanner not being able to connect to the computer cannot be caused by something wrong in the trans.
Engine codes should definitely be corrected because codes related to the TPS or MAF could cause the PCM to command too low a line pressure, causing rapid trans failure.

NikoKourm

It's just weird, this scanner has been working properly for every other problem that this truck has had in the past. Ever since the transmission stopped working properly back in November, it hasn't been doing much to help understand what's going on when the check engine light came on. It could be faulty, but it has worked with my family's other vehicles since.

So could that potentially be the ailment of my transmission at the moment, that the PCM isn't commanding the pressure properly because of the TPS/MAF?

If so, how could I know for sure when it is corrected that it will be running properly? I brought it to the dealer last weekend, but they weren't willing to do anything for me but take apart the transmission with the symptoms and situation I described to them. Could/should I bring it in with this check engine light and finally get some help?

mrvedit

Purchase the ATD-5550 trans pressure gauge (about $35 on Amazon) and connect it to your trans. The pressure at idle should be 50+ PSI. In Reverse it should rise to around 150 PSI. Blip the throttle and it should jump to around 200 PSI. If that throttle blip gets you a big jump the PCM and engine sensors are probably working correctly.

Other than that you need to get the scanner issue resolved. If other scanner also don't work, it may be a frayed wire near the OBDII connector; sometimes even a bad PCM.

NikoKourm

Okay I will take a look into that option.

If it doesn't work out, would that direct me to the input drum once again or would the PCM (and potentially MAF/TPS) be the problem?

mrvedit

If the pressures are low, we have to determine if it is a sensor/PCM/tune problem, a bad Pressure Control Solenoid (PCS) in the trans or something else in the trans.
The possibilities are too many; it is best to reduce them with some diagnostic tools and procedures.

If the pressure is good, I would suggest hanging the gauge from your outside mirror, routing the hose away from suspension and exhaust and going for a drive to confirm that you get 200+ PSI at WOT.

I recall a thread where the OP claimed to have ruined three sponsor built 4L65E in one summer. Obviously he claimed the trans were defective, but I'm confident the PCM just wasn't commanding high line pressure at high throttle. The pressure gauge is the only way to be sure. Even a scanner showing PCS current only indicates what is being commanded, not what is actually happening.

NikoKourm

Okay, well I just ordered that transmission pressure gauge to do the job, I will update you when I see what's going on.

NikoKourm

Apparently the computer that we borrowed from my brother's friend was able to read the pressures in the transmission too. I will have to check it out on my own because my brother and dad can't tell me what the pressure ranges were, but they said from the electrical signals that everything seemed to be in the proper ranges for drive and reverse.

Again, I asked them what the readings were saying and they couldn't tell me. I am still going to try the transmission pressure gauge when it gets here later this week.