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k72nova
05-22-2023, 11:21 AM
Short Question: What would cause a 4L65e to only work for a few hundred feet before giving out, not throwing any codes

Longer Story: I’m starting a new project which has the foundation of a 2001 Yukon Denali. I bought the Yukon cheap because the transmission doesn’t work. Well I go pick it up and drive it right onto the trailer, yay! Except when I’m pulling it off the trailer, I get about 120’ and the trans stops working. Come back a couple days later and move the truck maybe another 200-300’ and before giving up, again the next day. Anyway I bought the truck with the intention of buying a junkyard 4L65e and swapping it but I’m starting to think if I can just fix the one that’s in it I would rather go that route since I’m having a hard time finding anything but a 4L60e. The guy I bought it from tells me it’s the second transmission this has had in it and it was replaced roughly 40k miles ago. They tried putting a new trans cooler in it thinking that was the issue but that didn’t fix the problem. The trans is full of fluid, that’s the first thing I checked. I’m wondering what could cause it to only want to move when it’s cold? I’ve tried running the trans through the gears and they’re all neutral after a few hundred feet.

Hotwire
05-22-2023, 11:27 AM
Possibly the trans filter seal? When the trans stops working, check the fluid and look to see if the fluid has any bubbles on the dipstick?

k72nova
05-22-2023, 05:35 PM
Possibly the trans filter seal? When the trans stops working, check the fluid and look to see if the fluid has any bubbles on the dipstick?

I'm in the middle of stripping the Yukon right now but I hadn't thought about that, once it's stripped and just a carcass I should be able to run it around the field to test it. Thanks!

Wardawg1
05-23-2023, 08:38 PM
Since you say the trans is full of fluid while in park with the engine at idle ? .... You describe a situation where the trans filter is clogging up. As the trans sits for a day or so the converter drains back, flushes the filter out a bit. Start the vehicle up and it will move for a short distance till the filter clogs again.

With the pan off , I would check the filter for a cracked plastic tube that slides into the pump. If that is OK, break the filter open to look inside for debris in the filter material