Need advice on changing out radiator cooling lines for 2001 gmc sonoma 4.3 2wd

I was driving down the freeway and my truck started driving rough. Pulled over and saw transmission fluid dripping out everywhere. It went everywhere. It even managed to get on the tailgate and the outside of the rear wheels. I’m pretty sure one of the cooling lines went out. The dripping is on the passenger side where the lines run and the fluid came out really fast.

I’m wondering if there is a trick to get the lines disconnected from the transmission. I ant find a video or guide on it. The lines run to the top of the transmission, but I can’t see where and I don’t think there will be enough space to get my hands to where the lines connect. Any advice would be great. A video would be awesome. Thanks in advance.

Also I’m pretty sure its a 4L60E tranny and it has an auxiliary radiator in front of the main one.


@Tester beat me to it. I was going to post a different video of the same procedure. The video shows the connector at the radiator. It should be the same procedure at the transmission.

A note on reassembly: the clip must be reinstalled in the adapter first, then the line is pushed in until it clicks.

On the 4L60E, the lines go into the right side.

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To me the harder part would be getting them disconnected from the radiator. I have had the line get a hole rubbed in it along the horizontal path. That might be something to look for and as a temporary fix and piece of rubber fuel line hose double clamped could get you to a shop for them to replace the lines.

Thanks for the picture that helps a lot. I didn’t realize there is an adapter. Is that something I need to purchase or does it come with the lines?

I swapped out my radiator once. Getting the lines off that was pretty easy.
I thought the lines were solid metal…

Yeah me too if you can reach them and if they aren’t all rusted so you end up twisting the insert off. Depends how old and access.

The adapters are the part that the tube fits into and are screwed into the radiator and transmission. No need to remove or replace.

The clip was pretty easy to remove and pull trans line on mine, 03 trailblazer but looks the same. Pick up a couple extra clips, in case one springs into nowhere like mine did. Friends call them jesus clips, jesus where did that go?


Lol. I just lost the clip holding my cruise control cable in place. I didn’t see it come out. It happened instantly.

Thanks for the tip. You probably saved me from having to walk down to Autozone.

Those oil cooler line fittings (adapters) have o-rings in them. If possible, it would probably be a good idea to replace the o-rings.

Thanks. Do you know what size that would be or where I an find them?

Sorry, I don’t know the o-ring size. GM doesn’t seem to list the o-rings separately, but there are aftermarket kits available for the 4L60E that include the clips and o-rings. I’d think they would be available at any good parts store. For o-rings alone, you can remove them and have them matched up at a parts store. My local NAPA has a selection of o-rings.

Here’s a Youtube video showing the o-ring replacement on a fitting that has been removed from the vehicle.

Just buy the adapter fittings be done with it.


@jameson.luttrell_154832, if you decide to go the route that @Tester suggests, be advised that the fittings at the radiator and transmission are different. The link above for the Dorman 800-605 are for the radiator. At the transmission, Dorman 800-604 would be required. The thread sizes are different.

I just Called Dave down at CarQuest/Advance Auto Parts, and they have a complete adapter fitting set for both ends of tranny lines for $23.00 for the 4L60E transmission…

How convenient is that?