Leaking transmission fluid out at the connection site of the coolant line at the radiator?

MONARCH86

MEMBER
2005 GMC YUKON
1.5L
V6
2WD
AUTOMATIC
250,000 MILES

We have a heavy leak coming out at the connection site of the coolant line at the radiator. We have tried every which way to plug it or slow the leak, with no success. It almost acts like it's not a leak in the hose or at the connection site. It almost acts like there is no pressure and that's why it won't hold a seal. It's acting clogged.

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Yep, those fittings can be tricky. The pressure shouldn't matter, the line should stay secure and sealed. Here is how are the instructions on how to do the job. Make sure the seal is in good shape as well. Check out the images (below). Let us know if you need anything else.

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Saturday, February 24th, 2024 AT 10:09 AM

MONARCH86

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Also, the fluid is dark, and it acts like it's gummed up. Would replacing the radiator fix this and have a new filter and transmission fluid replaced? Would this fix the issue? As it sits, we can temporarily plug it by wrapping a rag around the line and put more transmission fluid in it and we can get it to shift, but it's constantly leaking and within minutes we are right back to it slipping. We have to walk everywhere. What's the cheapest direct fix? Can I just replace the radiator and have new fluids and filter replaced? Or will it be more complex and need a new transmission? We just replaced the water pump and serpentine belt.

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Saturday, February 24th, 2024 AT 11:36 AM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

It sounds like the transmission slips when it is low which is normal, I would replace the radiator to fix the problem. The transmission might be damaged, but you won't be able to tell until the fluid leak is fixed. Here is how to change the radiator out, which will come with the new transmission line fittings. Check out the images (below). Let us know how it goes.

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