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I am rebuilding this 2007 stock 4l60e. It has 289000 miles on it. Problem with it was the typical loss of 3rd and 4th gear. Ran fine until it shifted into 3rd. Cause was a leaking transmission cooler line that was leaking for a long time,
and the leak was caught too late. Owner tried to simply change the toasted fluid and run it - but it didn't work. Over heated bad, 3-4 clutch pack is burnt - apply pistons and the input shaft teflon seals do not seal and the drive shell almost stripped out the splines (the sun gear splines are very loose).... So I am confident I found the cause of the failure.
HOWEVER - upon tear down I found this casting flaw in case where the valve body sits. The gasket shows to have never sealed around this area.
I know I am the first one to take this tranny apart, and keep in mind that it ran perfect for 289000 miles with this flaw. It is definitely a casting flaw and NOT a chip or anything like that - somehow left the factory like this...
Question is - Should I be concerned about this case flaw? If so, what could be done about it?
I am not a transmission pro, and do not know the hydraulic circuit where this flaw is - so can someone tell me what this may affect?
That bullieton is not really related to the OP. That LONG straight wall that's inside the square on your pic is all for line pressure. Long straight wall=lots of surface area but not alot of support. Hence why it would crack there.
The OP has a crappy casting job between channels 38 and 41.
38=d2 oil from manual valve
41= LO oil from manual valve
Since I'm doubting this vehicle was hardly (if ever) used in D2 or Low, i bet that's why it never showed up as an issue.
If it WAS used in either of those ranges, it was probably LO and not D2...in which case the crossleak wouldn't matter at all. because d2 oil would be seeing pressure anyway.
Use the case. No biggie. It'll be fine for another 289k miles unless going in something that's going to spend all of it's time in D2
Thanks a lot for ALL the information! It definitely is a casting flaw, not a blow out or crack.
This is out of a Tahoe that was a grocery-getter and I think it taught a kid (or two) how to drive..lol
With this information, I doubt there would be a problem, but I will just probably just change the case.
I think I got a deal on amazon - $130 for a new case. Seems cheap for a new one (maybe it was dropped?lol) we'll see.
Thanks again for the info...
Call Teal Automotive in Indiana (765 768-7726) for the case. Much cheaper than what you have been quoted. Talk to Cheryl and tell her I sent you, and you will get the same price as me.
Thanks a lot for ALL the information! It definitely is a casting flaw, not a blow out or crack.
This is out of a Tahoe that was a grocery-getter and I think it taught a kid (or two) how to drive..lol
With this information, I doubt there would be a problem, but I will just probably just change the case.
I think I got a deal on amazon - $130 for a new case. Seems cheap for a new one (maybe it was dropped?lol) we'll see.
Thanks again for the info...
In my shop, we offer metal fabrication services and would generally repair that case (Heli-Arc) and machine it for about $35.00.
There may be some aluminum repair businesses in your area.
You can request a repair consisting of welding and machining.
If you find someone that will do it for under $50.00... Go for it.
If not, you can get a replacement case in that price range as PBA said... Try his guy.
Being that it is in a 'not so important area' - I will weld it myself - just enough to get the gasket to seal, and experiment with this case to see if I can blow it up in D2 or LO....lol
But, the new case one will be at my door today, so I will put that one in the Tahoe and see how that goes. I got it with a known bad transmission for a grand, so if I screw it up, it won't be too bad on my wallet.
Thanks for the info on Teal, I will keep them in mind on the next build.
And Thanks to everyone for all the info - it really helped me on this one.!!
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4l60e case casting flaw 
