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'12 6L80 Question

Chevy305

Chevy305

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Hey so I have a '12 Silverado 6.2 with a 6L80. I recently had a transmission cooler line rust out and leak badly so I replaced the lines and in the process I cracked the stock transmission cooler. I replaced that with an aftermarket Hayden unit that uses just barbed hose connections because the lines I got from the parts store didn't fit properly so rather than ripping out the lines that I just installed I figured just make up some hoses and call it good. Well one of the hoses popped off the new cooler on the way home today and made a huge mess. The transmission started shifting funny, then started slipping, then slamming into gear and slipping again so I pulled over after a few miles of this and found the blown line. To get it home I had my wife bring me some tools and ATF out to where I pulled over. I bypassed the cooler by looping the lines together as the rubber line kept squeezing off the hose barbs on the cooler. I topped off the ATF which was only about 1.5qts low. I drove it home and it shifted fine.

I plan on doing a pan drop and filter change, but do you think I did lasting damage to the transmission? It's got 110k miles and I had the tranny flushed before by a Chevy dealer around 75k but the filter is still original. I'm shocked that I only lost 1.5qts. are these tranny's that sensitive to fluid level?

The rubber hose I used came with the Haydon transmission cooler and it looks like a Gates overseas rip off and is actually 11/32" not 3/8". Which being smaller makes me think it would be less likely to pop off of a 3/8" barb. The hose feels a little soft after just 60 miles on it. Anyone recommend a specific hose that's rated for transmission fluid?

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Maybe. 1.5qts ain’t a lot but those trannies are sensitive also. Only time will tell. Weird noises and banging generally is a bad sign but I’ve done worse to others.
 
I wouldn't be overly concerned. Get it back in shape and completely full, then drive it a while before you make any decisions.
A quart and a half is actually a fair amount when it's running down the road.
I have seen the low to full marks only be a pint and a half on some. Ran a 700R4 home low on oil where it wouldn't take 4th anymore, (held 3rd fine) because the t-case was falling off. It is still going after repairs and topping it off then.
 
I used some pushloc hose for fuel/oil from somewhere that was rated at 300* and 250#. Maybe a Jegs brand IIRC. Been a while. If all else fails Parker should have something.
 
Those hose clamps are way too long as well. At least with conventional wisdom. Might they be a problem? Well, they popped off, so...perhaps?

I have come to not like that style clamp, I prefer having an assortment like this around: https://www.amazon.co.uk/Glarks-120Pcs-Injection-Assortment-Diesel/dp/B07HNWWLTY

Takes a bit more time to find the proper "fit" with that style, but they clamp evenly. Too long conventional-style hose clamps and they don't contour well to what you are clamping.
 
Just bought a pack of fuel injection hose clamps and a section of actual Gates transmission cooler hose and it feels much higher quality than the knock off stuff that I used. Hopefully I can get the pan dropped and by the end of the weekend and see how it all looks.
 
It should be OK, those transmissions are actually pretty resilient. The number one failure on these is the torque converter clutch which is woven carbon fiber and quite brittle. When the clutch frags it fills the trans with debris very quickly and clogs the filter. I've seen it happen over 200K miles and as few as 60K miles, if you notice converter clutch slippage stop driving and replace the converter and service the transmission. This is a very good transmission otherwise.
 
The correct size clamp 8s key. The gear style are for emergency repairs. The ones dyeager535 posted are worth the money.
 
Greg Ducato said:
It should be OK, those transmissions are actually pretty resilient. The number one failure on these is the torque converter clutch which is woven carbon fiber and quite brittle. When the clutch frags it fills the trans with debris very quickly and clogs the filter. I've seen it happen over 200K miles and as few as 60K miles, if you notice converter clutch slippage stop driving and replace the converter and service the transmission. This is a very good transmission otherwise.
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Greg, thanks that makes me feel better.
I have heard about the torque converters and i did some messing around with HP tuners. I found out that the factory tunes in a certain amount of slip when the converter is locked. So i zeroed out the desired slip and ramped up engagement pressure.
It feels better but I do still have some converter shutter and some slippage under higher loads like cruising uphill. I just hope this is helping and not hurting because it is slipping far less than originally.
 
I had the same thing happen to my 10. Lost enough fluid that it stopped engaging and that’s how I knew it was messed up. Had the tranny shop replace lines and cooler and lost four quarts before it was losing power. It’s been three years and it’s still going. But third gear is starting to slip before engagement now. Hopefully yours gets better with time.
 
Greg Ducato said:
It should be OK, those transmissions are actually pretty resilient. The number one failure on these is the torque converter clutch which is woven carbon fiber and quite brittle. When the clutch frags it fills the trans with debris very quickly and clogs the filter. I've seen it happen over 200K miles and as few as 60K miles, if you notice converter clutch slippage stop driving and replace the converter and service the transmission. This is a very good transmission otherwise.
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Did they fix this issue on the 2015's 2500hd?
 
The biggest killer I’ve read is lack of required fluid changes and the converter being locked up at all times and the computer allowing for some clutch slippage. If you’ve got HPTuners or EFI Live, you can remove the lock up in the lower gears and reduce the allowed slippage to zero to help. Wish I had known the tuning thing before I lost my trans. My Durango has the same goofy thing and I just finished tuning that out. Made a big difference around town. Like it got a little stall converter in it.
 
Dropped the pan today. While the fluid was dirty, it didn't smell burnt and there was basically no debris at the bottom of the pan and not much on the magnet. Pretty good for 112k miles and running it low on fluid. Just gotta finish up reconfiguring the cooler lines and the truck should be back on the road by bed time.

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Test drive went well! No leaks and shifted like it should. It took about 7 qts which was a tad more than I expected. I only had 6 qts of Dextron VI so the last quart was a random bottle of Dextron III. They're supposed to be forward compatible so oh well it's late and the stores are closed.
 
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