6L80 Air Check - Pump, Drums and Compensator Feed
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- Опубликовано: 15 сен 2024
- I show an air check of a GM 6L80 pump and drum service pack which includes the 1-2-3-4, 3-5-R and 4-5-6 clutch packs as well as the Compensator Feed circuit. Air checking these parts on the bench will help you confirm subassembly build-out was done correctly or find and fix issues before the case goes together.
Also applies to 6L45, 6L50 and 6L90 transmissions.
I'll probably do a follow up video to this one showing the air check of the low reverse and 2-6 clutch.
You make the best video's ever Man!!!! Thanks
Thanks a bunch, HMG!!!
So I have my 6L90 completely together except the valve body, I did replace the turbine shaft fluid seals, resized by wrapping with thin plastic then pulling a zip tie tied around each one and slid stator over smoothly, I believe they are good. When air checking I get very good apply on the 1234 and 35R and when I pull the nozzle off significant pressure releases, so I think they are sealing well and working. Using about 40 psi of air. But, when I hold the pressure on and put my finger on the other opening I get a tiny bit of air, barely noticeable, but you can feel a tiny pop if you hold your finger there a few seconds then pull it off. I feel like it's probably just needing the heat cycle you mention for the rings to fully seal, but figure I need more reassurance. The 456 seems like it applys firmly the first puff of air, then not as firm the second time I put air to it, I don't hear any weird noises or air wooshing out, but it definitely isn't as firm/solid as the 1234 and 35R. I feel like it's probably normal listening to air checks on youtube, but again, have to ask. Thanks a bunch, Also ordered a shim kit because my end play seems nearly non existent, haven't put a mic on it yet, but I'm betting it's only a couple thousandths so figured I would get a kit to have in case I do need to increase it.
Hi Justin,
Nothing you've stated has me concerned however I'm not there with you so can't say to a 100% certainty there's no problem but odds are against...Double check your stator inner diameter for any sealing ring groove wear (if you haven't already done so) and then try wiping a bunch of transmission fluid in the stator's inner diameter then re-check to see if there's any difference...Brand new teflon sealing rings like the sort on the input shaft really need to be 'used' before they really seal...You'll find that used sealing rings in good shape, such as the ones on the input drum in this video, will actually air check "better" than new ones...nothing to be concerned about as long as you get apply and when putting air into the circuit, you're not able to physically move the clutch pack around when it's being compressed with air.
I understand what you are talking about and this may give some insight as to what is going on. When you replace the seals there is a sizing tool designed to return the stretched seals to their proper dimensions. You used a zip tie and reduced the size of the seals to the dimensions of the shaft but the seals are supposed to be slightly larger then the shaft so they can seal against the corresponding part. I would imagine that once they were warmed up they grew into the proper size and didn’t give you a problem.
@@nickstransmissions Well I finally had time to finish putting the transmission in. Warmed it up, did the reset with a basic scan tool that says it had the ability to "reset" the 6L transmissions, got it up to temperature and drove it around a mile or so, didn't really trust it so just got and used HP Tuners to reset, then did the fast adapt relearn which went through the gears while I held the brake down. Drove it around the block a few times and a short stretch of road a few times. It has a delayed shift into 3rd or 4th. Seems like it's third based on speed, but looking at the last shift times everything is about .3 to .4 seconds, but 4th was .65 seconds. It's like it starts to shift, nothing happens for a beat, then it shifts a little harsh. Everything seems pretty smooth but that. Before I pulled the transmission out, it was an auction buy I never drove before, I changed the filter and drove it around the block and it had pretty much the exact same shift, I just figured it was the transmission needing a rebuild. I've seen posts of people having the transmission flashed and upgraded at the dealer fixing what sounds similar, it makes me wonder if I can adjust it out with HP tuners, but don't want to start messing around trying to hide it if I should look at something else first.
Hi Nick
I am air checking new Teflon stator seals late design with oring behind
I am getting a slight cross leak at 3-5-R when testing 1-2-3-4
I am getting a bad cross leak at 1-2-3-4 9:30 when air check 3-5-R
Is this normal with brand new seals
The X-leak at the 1-2-3-4 when testing 3-5-R is normal as both circuits are energized in 3rd and 5th gear; the #5 check ball in the valve body partitions the circuit for when in Reverse. Slight cross leakage into the 3-5-R when testing the 1-2-3-4 is also normal on the bench with dry parts as air can get into places fluid cannot so you'll always hear a small amount of cross leakage with teflon, plastic-style or any other type of sealing ring that isn't rubber.
That said, check all of your seal-bearing surfaces for wear such as the inner diameter of the stator on the pump as well as the inner dia of the 3-5-R drum...Check your seals as well, make sure none were damaged at any point.
Great video and information!
Thank you for making this detailed video. Such a great help for all of us who are not too familiar on how these units work.
quick question; Is it normal to get some air coming out of the compensator feed hole while testing 1234 circuit?
Also, 1234 applies well, but there seems to be a hissing noise inside the drum. wich makes the circuit not to hold for long if the trigger on the blow gun gets released.
Any thoughts would be greatly appreciated!!
You're welcome, Jose and thank you for watching!
Generally you don't want to hear any hissing coming from the CF when air checking any of the clutch packs, otherwise that indicates cross leakage into that circuit...This video was made in response to a fellow form member on Silveradosierra.com who was having the same problem. He was able to trace the source to a slight imperfection in the casting itself and so at the time of this comment, in the process of remediating the issue.
@@nickstransmissions Thank again for taking the time to reply. This helps a lot greatly appreciated!
Best regards
You're welcome, man - let me know what you ultimately find and how things turn out.
Thanks for great video, I got 6L90 and No forward and no reverse, Can I still test with this one, What do you suggest to check, we took the 456 drum and clutch was toasted but is there any relation between this drum and no movement?
Thanks for the kind words, @houshang212!
No causal relationship between a smoked 4-5-6 clutch and no movement in any gear/range at all...
Check your valve body for migrated or worn check balls...#1 check ball gets stuck or migrates out of position, you will have no forwards movement. #5 check ball does same, you'll have no reverse. Other no-movement causes include stripped input shaft splines, destroyed pump rotor/slide, stripped 3-5-R and/or front planet splines, torque converter (rare) or exotic form of TEHCM failure (rare, TEHCM issue usually generates DTCs).
There may be others but the above are the most common ones.
Where are you located? have a 2012 6l80 slow to accelerate cleared adaptvs with hp tuners took on test drive power/torque is restored for a few miles then returns to limp mode I guess suv had no codes stored for trans
Hi Ryan, thanks for watching...I'm in Socal/SW region, where are you located?
@@nickstransmissions SoCal Fontana area
Please send me a direct message on Tahoeyukonforum.com with your contact number. My name on there is Nicktransmissions; I'm not too far from you.
Hi! Great videos! I was using this one to air test my 6l80. My rebuilt 456 would not engage when set up as yours is. However, it checks perfect when tested alone. I replaced the pump/stator and housing as part of my rebuild. Curiosty got me, so i put the 456 into the old stator assembly, and it tested good so I removed both stators and swapped the old stator onto the new stator support. Reassembled the assy. Tested good. Built up the whole pump/housing assembly the way you have it there. It CHECKED! 3 times in a row! 4th attempt, no more engagement. 😔 any ideas? They are new orings, guides, and teflon support rings.
Hi James, thank you for watching...I'd carefully look over your stator support to see if it's cracked in any way, shape or form or if the gasket between the stator and pump cover was compromised (or left off). That's the only thing I can think of beyond cut turbine shaft sealing rings which doesn't sound like the problem.
How do I fix the cross leaks
Replace the separator plate between the two valve body halves, valve body-case/pump rubber seals, sealing rings on the stator and input shaft as well as that gasket between the stator and stator support...Also make sure your valve body / TEHCM assembly is secured to the case properly.
That's it!
Hi; what can be the reason behind cross leak?
Hi Shantanu, thank you for watching...There's a few things:
1. Worn pump stator sealing rings
2. Worn turbine shaft sealing rings
3. Worn pump stator to stator support gasket
@@nickstransmissions Thank you!
@@nickstransmissions Hey! One last question, is it normal for pressure to leak from the boost valve on the pump when we do the air test?
Are you subbed to my channel? If not, please do so - it helps me help you!
a very minor amount of leak is normal but it shouldn't be pronounced. That said you shouldn't be installing the factory boost or pressure regulator valve back in, if that's what you're doing.
When it comes to automatic transmissions I am completely lost😢 manual transmissions heavy equipment stuff no problem but automatic transmissions not my cup of tea
Keep watching my videos and you will no longer be lost :)
Do you do great work but you talk a little too much
It's a balancing act; one that I have yet to perfect...That said, I'd rather give a little too much information vs not enough.
Thanks for watching, David.