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We now know that your trans can produce high pressure.
As I mentioned before, now re-connect the trans harness and monitor pressure while you drive. If it stays low, then mostly likely the PCM is commanding low pressure; and the most likely cause of that is a bad TPS or MAF.
I'm still inclined to believe the PCM is commanding low pressure and this caused your 3/4 clutch to fail prematurely.
There have been plenty of posts about people having premature 3/4 clutch failure even with sponsor built transmissions. They usually continue the "4l60e is crap" message even though they never checked their line pressure under acceleration.
Alright I am about to go do that, both with and without the PCM installed. Is it okay if I leave my front driveshaft out for the job? Also what type of pressures should I be looking for, if they are on the lower range then that would be a bad signal?
Here is my input drum before I did a little filling and sanding on the lugs. Still working flawless 10,000 miles later.
Thanks a bunch for letting me know that. I've been looking endlessly for information about whether or not that would be problem for me or not. If it's not, then I won't worry about it and won't take the transmission apart if it is simply the TPS.
I still stand with you have a pressure issue no line rise on acceleration or a leak in the 3-4 clutch or drum. The marks / scars on the drum would not cause your issue . And as mentioned no or low line rise due to a host of issues is a common cause of 3-4 clutch failure though the trans itself is generally blamed,
Okay so I just conducted my test on the road for the last two hours (not driving, just setting up, doing the test, then taking apart).
So, when I unplugged the PCM and put her into drive, I noticed the slow acceleration at first. As I went up 20 mph, I had my fingers crossed. Speedometer kept going up no problemo, but obviously the engine was running at really high RPM. So I got up to about 40 mph with the engine at about 5000 RPM. So I guess this means my 3rd gear is functional in max line pressure mode. I also put the truck into manual 1 and 2, those worked as they had prior.
As for the gauge test. I plugged the PCM back in, I hooked up the gauge and I taped it next to my side mirror. Again, the truck in drive would shift fine from 1 to 2, but going to 3 it seemed like it would try to do it, but it would just rev high and not accomplish anything.
I switch through all the gears in idle and here's what I got (approximations based on what I could see):
Park - 52 psi
Reverse - 74 psi
Neutral - 52 psi
Drive - 52 psi
3, 2, 1 - 52 psi
As for blipping (I couldn't actually blip it the same way each time, so these are also approximations):
Park - higher than 75 psi
Reverse - higher than 100 psi
Neutral - about 75 psi
Drive - about 75 psi
3, 2, 1 - about 75-90 psi
As for moving the vehicle (again approximations):
Park - 75 psi (not moving)
Reverse - 165 (hard gas initially)
Neutral - 75 psi (not moving)
Drive - about 60-70 psi
3, 2, 1 - about 50-70 psi
Again all these readings I got were hard to determine what was going on and how to keep everything constant. I brought the truck to an empty parking lot down the street from me. I was able to have about 100 ft of space to conduct the tests.
So, when I unplugged the PCM and put her into drive, I noticed the slow acceleration at first. As I went up 20 mph, I had my fingers crossed. Speedometer kept going up no problemo, but obviously the engine was running at really high RPM. So I got up to about 40 mph with the engine at about 5000 RPM. So I guess this means my 3rd gear is functional in max line pressure mode. I also put the truck into manual 1 and 2, those worked as they had prior.
Well it must not have been 3rd gear because I was revving up at 5000 rpm going 40 mph.
Ok I am assuming you gave throttle when driving and hopeful kinda hard throttle and never saw more than 90 PSI in drive accelerating that is pretty low,
So I still suspect not or inadequate line rise. But the neutral feeling when the 2-3 shift is supposed to happen points back to a Hydraulic leak in the 3-4 clutch circuit same with your unplugged test with the fluid venting someplace in the drum or ring area The D3 or D4 position with harness unplugged would still be first gear and the other feed would would still be able to release the band,
I think you have an issue in the drum and need to completely disassemble pistons and all and take photos of all of it for us
Something is wrong there.
As for the Line rise part your info is not clear so I cannot say its actually an issue, But even so you would have third not a neutral feeling under light throttle.
My suggestion is remove trans disassemble remove input drum, Completely disassemble the drum pistons and all take photos if everything and inside drum, Also the rings on input shaft.
My theory as your burning the overrun clutches also is the green oring inside the drum is MISSING or badly damaged or one of the teflon rings on input shaft is torn or missing.
Ok I am assuming you gave throttle when driving and hopeful kinda hard throttle and never saw more than 90 PSI in drive accelerating that is pretty low,
So I still suspect not or inadequate line rise. But the neutral feeling when the 2-3 shift is supposed to happen points back to a Hydraulic leak in the 3-4 clutch circuit same with your unplugged test with the fluid venting someplace in the drum or ring area The D3 or D4 position with harness unplugged would still be first gear and the other feed would would still be able to release the band,
I think you have an issue in the drum and need to completely disassemble pistons and all and take photos of all of it for us
Something is wrong there.
As for the Line rise part your info is not clear so I cannot say its actually an issue, But even so you would have third not a neutral feeling under light throttle.
My suggestion is remove trans disassemble remove input drum, Completely disassemble the drum pistons and all take photos if everything and inside drum, Also the rings on input shaft.
Alright, that's my next step when I get the chance to. There has to be something innately wrong with the drum that I just couldn't have seen. That or I should've just replaced the seals even though the guy on TransmissionBench said it wouldn't be necessary.
I went on a limb and spent money on a new TPS just to be sure. I replaced it and I'm still having the same problem. So we can scratch that potential electrical problem out.
Alright, that's my next step when I get the chance to. There has to be something innately wrong with the drum that I just couldn't have seen. That or I should've just replaced the seals even though the guy on TransmissionBench said it wouldn't be necessary.
I went on a limb and spent money on a new TPS just to be sure. I replaced it and I'm still having the same problem. So we can scratch that potential electrical problem out.
Actually looking at the photos so far I do not see the GREEN ORING at all inside the input drum ,
This missing would connect the forward clutch oil to the 3-4 clutch circuit,
But unless you put it back in the one photo of this area you show it is not present .
Actually looking at the photos so far I do not see the GREEN ORING at all inside the input drum ,
This missing would connect the forward clutch oil to the 3-4 clutch circuit,
But unless you put it back in the one photo of this area you show it is not present .
So that's something the guy at the dealership brought up to me and I felt like a potential moron, however I am very sure that I did in fact replace it. My first piece of evidence is that I don't have it in my left over parts. My second piece of evidence are these following pictures, one where I am showing everyone that I removed the old one and the other that shows a tiny green sliver of where I put Assemblee Goo over the O-ring.
However if it is in fact not there, then I am going to feel like a total moron, yet be completely appalled by the fact that it's nowhere to be found. It's possible, but I know I took that picture of the old one because I was trying to show that there was an O-ring there and that I was replacing it. I wish I had sure photographic evidence that I did in fact put it in, but my camera kept dying on me due to the cold temperatures in my garage.
Also while your at it even if the green ring is missing after replacing ring , Also get a new pressure control solenoid its good insurance,
Should I even bother? I just got a brand new one (along with every other electronic component) specifically because the transmission was burnt out completely.
I see the green oring in your picture but not in he drum bot its seems to be on the 3-4 apply piston,
Marked in orange is where it should be in my photo not on the apply piston it is however now likely to stretched to work you will need another and yes if you have replaced the PCS do not worry about it again,
In the last photo I drew a green line in the groove it belongs in .
Alright thanks for the heads up. I won't be able to look into it again until next weekend, hopefully I can get everything off and apart over the weekend. I will post pictures of the entire input drum and will keep you posted.
Again, still going to feel like a moron if it's something small like this that I overlooked.
Well you obviously have the green ring on the apply piston in this photo so I would bet that's
it
Definitely interesting you point that out. I don't think I did do that (I think I would've realized that the green ring isn't supposed to stretch that much), but I will look at it and take pictures of it all when it comes apart again.
Since you stretched that O-ring so much, it would not have seated in its groove and when you installed the forward/overrun combo it may have gotten pushed down.
BTW a simple "tool" called the Lip Wizard is very useful, almost necessary, for installing the pistons into the input drum and not damaging the seals. It comes with some rebuild kits and a local trans shop can often spare one if you ask. Or a few dollars on ebay.
I haven't fully removed the transmission, but I did get a chance to drain some of the fluid out today. I noticed that the fluid was darker (and milky?) and definitely had some sediment in it, and some metal shavings. It doesn't look black like it did before when I knew for sure the 3-4 burnt out, but I am afraid the friction material/clutches are getting burnt out somewhere even though I've only driven the truck for about four hours total since the rebuild and haven't been able to get out of first or second since. Could this be due to me driving the truck in 2nd for most of that time, I am wondering if maybe the clutches that command 1-2 were working too hard for the time they were used? Again, it's not a lot of sediment in there, but it's noticeable; the fluid alone still looks quite red.
I am going to fully remove and take it apart between tomorrow and the following day and I will get as many pictures of the insides as I can.
03-03-2017, 09:34 AM
