4L60e issues after rebuild

[NickTransmissions]

@NickTransmissions - Thanks for such a prompt reply! You are beyond awesome, hats off to you!

Back to the issue, I always set the case valve body side up (with the valve body removed) and level out the back, put a few drops of transmission fluid where the check ball goes and check to see if any of it comes out inside the case or if it all comes out through the servo bore. Then I start with the assembly process. This has always tested out fine in the transmissions I have rebuilt. However, since I test it at the beginning, there is a chance that debris could get in there during the reassembly process. With the transmission in the vehicle, I cannot think of a way to test it properly, perhaps only drop the pan and valve body, remove the servo and blow some compressed air to see if that will clean it up.

Assuming there is no leak in the check ball capsule, could it be there is a leak in the drum that under normal 3rd gear pressure leaks enough fluid that the clutch pack is not able to stay properly compressed, but when it goes to 4th gear, the max line pressure is high enough to where the amount being leaked does not drop the pressure low enough to cause the clutch pack to not stay compressed?

Regarding the line pressure test, what readings should I expect to see while in 1st, 2nd and then finally when it shifts into 3rd? With the vehicle-to-transmission harness plugged in, I will not be able to get it to shift into 4th gear so I will not be able to get a reading for that gear. Should I instead try it with my testing device to get it to shift into 4th gear, or maybe run a separate test? From what I understand, the reading in Reverse is the max pressure, correct?

You're welcome. Pressures should be well over 100PSI when shifting and driving, even at relatively shallow throttle angles...If you have a bi-directional scanner, plug it in to monitor shift speeds and other relevant trans and/or engine parameters...You can perform a limp vs TCM enabled test with the connector plugged in first, then with your TCM by-pass device installed to compare LP readings under those two conditions if you want but perform the test with the PCM-to-trans harness/connector plugged in to the transmission.

Did you pressure test the forward drum to confirm/deny leaks at the base of the input shaft?

What was the condition of the 3-4 clutch pack when you tore that transmission down? Was it totally smoked, frictions wiped/coned or were the frictions/steels just worn or mildly burnt?

As I stated in my reply yesterday, there's very little chance the 3rd ACC check ball capsule is actually bad....I've seen one in my lifetime and that's having done 3,000+ 700R4s and 4L60Es and I've prob checked at least 80% of all those cases (I've since stopped as it's not really worth even doing, except when there are unexplained failures in the 3-4). One bad capsule-that's it...Dana @ Probuilt Automatics, who's built something on the order of 30,000+ of these transmissions has stated a few times that he's never seen one test bad after the case has been cleaned. They only leak when dirt/crud gets in, which usually happens if the lines and coolers on the vehicle are not flushed in advanced. So I wouldn't look there until you've ruled everything else out, which prob translates to you ending up with the transmission on the bench again and scrutinizing that capsule for crud/debris before cleaning the case.

Here's what I provide to all and verbally stress to my customers on an 8x11 sheet of paper so they get the message and understand the importance of flushing out the system:


It's possible that your buyer didn't flush his lines/coolers, had residual contaminants in the system and some of it is stuck in that ball capsule preventing it from sealing fully...But when you're in limp and have your TCM bypass device hooked up, you're working with max line pressures which enable enough net pressure at the 3rd clutch apply piston to keep that 3-4 pack held so you can grab 4th gear, at least for a very short while...Too bad you ran out of road or couldn't keep driving it to see if any subsequent slippage would have occurred, either in the trans or TCC.

ATM, my guess is you have leak somewhere in the forward drum which is resulting in lack of apply pressure and it's showing up as a no 3-4 condition under normal line pressures. It's also possible the 3rd acc CB capsule is gummed up...

 

[Tataocb]

You're welcome. Pressures should be well over 100PSI when shifting and driving, even at relatively shallow throttle angles...If you have a bi-directional scanner, plug it in to monitor shift speeds and other relevant trans and/or engine parameters...You can perform a limp vs TCM enabled test with the connector plugged in first, then with your TCM by-pass device installed to compare LP readings under those two conditions if you want but perform the test with the PCM-to-trans harness/connector plugged in to the transmission.

Did you pressure test the forward drum to confirm/deny leaks at the base of the input shaft?

What was the condition of the 3-4 clutch pack when you tore that transmission down? Was it totally smoked, frictions wiped/coned or were the frictions/steels just worn or mildly burnt?

As I stated in my reply yesterday, there's very little chance the 3rd ACC check ball capsule is actually bad....I've seen one in my lifetime and that's having done 3,000+ 700R4s and 4L60Es and I've prob checked at least 80% of all those cases (I've since stopped as it's not really worth even doing, except when there are unexplained failures in the 3-4). One bad capsule-that's it...Dana @ Probuilt Automatics, who's built something on the order of 30,000+ of these transmissions has stated a few times that he's never seen one test bad after the case has been cleaned. They only leak when dirt/crud gets in, which usually happens if the lines and coolers on the vehicle are not flushed in advanced. So I wouldn't look there until you've ruled everything else out, which prob translates to you ending up with the transmission on the bench again and scrutinizing that capsule for crud/debris before cleaning the case.

Here's what I provide to all and verbally stress to my customers on an 8x11 sheet of paper so they get the message and understand the importance of flushing out the system:
View attachment 422428

It's possible that your buyer didn't flush his lines/coolers, had residual contaminants in the system and some of it is stuck in that ball capsule preventing it from sealing fully...But when you're in limp and have your TCM bypass device hooked up, you're working with max line pressures which enable enough net pressure at the 3rd clutch apply piston to keep that 3-4 pack held so you can grab 4th gear, at least for a very short while...Too bad you ran out of road or couldn't keep driving it to see if any subsequent slippage would have occurred, either in the trans or TCC.

ATM, my guess is you have leak somewhere in the forward drum which is resulting in lack of apply pressure and it's showing up as a no 3-4 condition under normal line pressures. It's also possible the 3rd acc CB capsule is gummed up...

Thanks again for the explanation. I bought a pressure gauge from Amazon, but the hose is too short I think to be able to get it in the cab. I have never tried to use it. I have not been able to get in contact with the buyer. I will probably end up replacing it with another rebuilt unit.

On a different note, I was taking apart a core I received (people don't care about the condition of the core they bring, I have gotten some really bad ones) which came without the servo assembly and the guy drilled a hole in the pan (???!) to drain the fluid because the drain plug had stripped. So I took it apart today, it seems it is not the first time someone has opened it up since the sealing rings on the input shaft do not look stock. What I found is the checkball we had discussed previously is missing and they sealed the hole that would drain into the case (see pic), is this case junk?

 

[NickTransmissions]

Thanks again for the explanation. I bought a pressure gauge from Amazon, but the hose is too short I think to be able to get it in the cab. I have never tried to use it. I have not been able to get in contact with the buyer. I will probably end up replacing it with another rebuilt unit.

On a different note, I was taking apart a core I received (people don't care about the condition of the core they bring, I have gotten some really bad ones) which came without the servo assembly and the guy drilled a hole in the pan (???!) to drain the fluid because the drain plug had stripped. So I took it apart today, it seems it is not the first time someone has opened it up since the sealing rings on the input shaft do not look stock. What I found is the checkball we had discussed previously is missing and they sealed the hole that would drain into the case (see pic), is this case junk?

Lol, yea ive seen some wild stuff over the years...is that JB Weld? If so and the capusle is missing (and if you feel like saving the case), grind off all that stuff, completely clean the capsule bore then install a new check ball capsule. Many folks drill holes in the pan to avoid a trans fluid shower; some of my customers do it because they're having me install an aftermarket deep pan as part of the rebuild. I tell them to drill it toward the back and be careful they dont damage anything beyond the pan.

 

[Tataocb]

@NickTransmissions - it dies look like JBWeld, I will give that a try before discarding the case and just keeping everything else for parts.

I took apart another core and came across something I had never seen before. The guy replaced the trans because it was leaking from the smaller inspection cover and it was a high mileage vehicle so decided to get a rebuilt one. When I loosened the bell housing bolts, fluid started to leak from the second highest bolt on both sides. Is there something in the case that could leak fluid into that area or could it just be from a bad pump to case seal? Or maybe even a bad pan gasket somehow shooting up? That gasket's mating surface looks pretty wet. The bottom bell housing to case bolt on the drivers side was not as tight as the rest. It took minimal effort to get loose. I use a breaker bar because I stripped a few bolt heads with an impact in the past and drilling them out is not fun. This is a 2002 so it has the rubber o ring around the pump.

In the pics below I circled where I found it odd to see fluid and then drew arrows on the close up pic to some small puddles.

 

[NickTransmissions]

@NickTransmissions - it dies look like JBWeld, I will give that a try before discarding the case and just keeping everything else for parts.

I took apart another core and came across something I had never seen before. The guy replaced the trans because it was leaking from the smaller inspection cover and it was a high mileage vehicle so decided to get a rebuilt one. When I loosened the bell housing bolts, fluid started to leak from the second highest bolt on both sides. Is there something in the case that could leak fluid into that area or could it just be from a bad pump to case seal? Or maybe even a bad pan gasket somehow shooting up? That gasket's mating surface looks pretty wet. The bottom bell housing to case bolt on the drivers side was not as tight as the rest. It took minimal effort to get loose. I use a breaker bar because I stripped a few bolt heads with an impact in the past and drilling them out is not fun. This is a 2002 so it has the rubber o ring around the pump.

In the pics below I circled where I found it odd to see fluid and then drew arrows on the close up pic to some small puddles.

Take another look at those bolt holes, perhaps with a magnifying glass and tell me what you see.

Also, use a torch to heat up the case side of the bell-case bolts so you can remove them with an impact...30-60 seconds under the flame is usually sufficient but just go with as many cycles as necessary to get them loose. If you strip any in the future, use a small cut off wheel, cut a slot across the face for an impact driver and flat head bit then use that and heat to get them out.

 

[Tataocb]

Take another look at those bolt holes, perhaps with a magnifying glass and tell me what you see.

Also, use a torch to heat up the case side of the bell-case bolts so you can remove them with an impact...30-60 seconds under the flame is usually sufficient but just go with as many cycles as necessary to get them loose. If you strip any in the future, use a small cut off wheel, cut a slot across the face for an impact driver and flat head bit then use that and heat to get them out.

I took a look but did not see anything out of the ordinary. Some are a little dirty, but that is about it, no cracks or anything like that. I also don't see how most of them would be in contact with fluid from inside the case, except perhaps for the one by y he servo.

 

[NickTransmissions]

I took a look but did not see anything out of the ordinary. Some are a little dirty, but that is about it, no cracks or anything like that. I also don't see how most of them would be in contact with fluid from inside the case, except perhaps for the one by y he servo.

The second picture, pan bolt hole - it looks like a crack but could also be casting flash...I can't tell but if it's not a crack there, perhaps theres a crack somewhere else...Either way, you shouldn't be seeing transmission fluid coming out of those bolt holes when the bolts are removed. It's possible a leaky gasket could explain the fluid that has pooled just above the pan rail but if you're saying that fluid started to leak upon removing bell-case bolts, that seems like a case fracture to me. I'd tear it all down and clean the case so you can do a more thorough inspection.

I always tell folks in my videos - don't do any critical inspections until your parts are completely clean, otherwise you'll miss something subtle but critical.

 

[Tataocb]

@NickTransmissions - I come to you again for help. I am disassembling a core. I always air check even during disassembly to see if there are any issues that can be easily determined that way. When I blow air to check the overrun clutch, it does apply, but there is air coming out the checkball on the tip of the input shaft. Does this mean there is an issue with the shaft and how it fits into the drum (meaning it needs to be pressed out or the whole assembly replaced)?

What happens if air still comes out of there after reassembly with new parts?

 

[NickTransmissions]

@NickTransmissions - I come to you again for help. I am disassembling a core. I always air check even during disassembly to see if there are any issues that can be easily determined that way. When I blow air to check the overrun clutch, it does apply, but there is air coming out the checkball on the tip of the input shaft. Does this mean there is an issue with the shaft and how it fits into the drum (meaning it needs to be pressed out or the whole assembly replaced)?

What happens if air still comes out of there after reassembly with new parts?

Did you do a wet pressure test on that drum?

 

[Tataocb]

Did you do a wet pressure test on that drum?

I was doing an air check with the test plate with only the valve body off.

I ended up taking it all apart. When I air checked just the input drum (by blowing compressed air direcrly into the feed hiles on the input shaft), there was no air coming out of that check ball at the end of the shaft. I then put the reverse drum and pump and did another air check through the pump, and could feel some air coming out. That makes me think it is a issue with the top sealing ring. I will replace them all during the rebuild and will report back if that fixed it.

I am not familiarized with the wet pressure test procedure.