Coolant leaking from transmission cooler line

[muncie21]

I have a 2014 Yukon XL Denali with the 6.2 motor. I recently noticed that there's minor coolant leak/seep from the transmission cooler line, where it connects to the radiator side tank on the driver's side of the vehicle.

Thinking of tightening the fitting where it connects to the radiator, however I'm a bit concerned about cracking the plastic tank when I do this. Alternatively, does anyone know if there's an o-ring in this connection? If so, I may try to just replace the o-ring before I spend $$ on a new radiator and transmission line.

 

[wjburken]

I have a 2014 Yukon XL Denali with the 6.2 motor. I recently noticed that there's minor coolant leak/seep from the transmission cooler line, where it connects to the radiator side tank on the driver's side of the vehicle.

Thinking of tightening the fitting where it connects to the radiator, however I'm a bit concerned about cracking the plastic tank when I do this. Alternatively, does anyone know if there's an o-ring in this connection? If so, I may try to just replace the o-ring before I spend $$ on a new radiator and transmission line.

If you are seeing coolant, replacing the o-ring or tightening the connection will not help. You most likely have a crack in the radiator around the transmission line.

 

[OR VietVet]

If the line unthreads from the radiator ok you should not need a line. If you are leaking coolant from the line itself then you have coolant in your trans fluid. The only thing that should leak from the line is trans fluid. If you are talking about the fitting in the radiator, do not try to tighten. You will likely crack the radiator. If the fitting is leaking at the radiator then you need a radiator. Pics?

 

[muncie21]

The leak is definitely coolant and coming from where the fitting screws into the radiator. Found out that the auto parts place around the corner carries just the fitting. May try to replace it with a new one and o-ring before ordering a new radiator.

 

[wjburken]

The leak is definitely coolant and coming from where the fitting screws into the radiator. Found out that the auto parts place around the corner carries just the fitting. May try to replace it with a new one and o-ring before ordering a new radiator.

View attachment 236471

If you take that fitting out, you better hope only transmission fluid comes out. If coolant comes out, you need a new radiator and a transmission flush.

 

[muncie21]

If you take that fitting out, you better hope only transmission fluid comes out. If coolant comes out, you need a new radiator and a transmission flush.

Good point. Hmmm, sounds like a new radiator needs to be added to my Santa list

 

[OR VietVet]

I have a similar problem now except it feels like a hard transmission shift. It mostly happens when cold and rolling down the street out of my driveway. As I make a slight right turn and am about to give it some gas it hard clucks into another gear.

The leak is definitely coolant and coming from where the fitting screws into the radiator. Found out that the auto parts place around the corner carries just the fitting. May try to replace it with a new one and o-ring before ordering a new radiator.

View attachment 236471

Like Wade said, careful when you attempt to tighten. If is loose that means at one time you or a tech may have loosened the LINE and did not put a wrench on the fitting to hold it in place. Shit happens.

 

[kbuskill]

I have a 2014 Yukon XL Denali with the 6.2 motor. I recently noticed that there's minor coolant leak/seep from the transmission cooler line, where it connects to the radiator side tank on the driver's side of the vehicle.

Thinking of tightening the fitting where it connects to the radiator, however I'm a bit concerned about cracking the plastic tank when I do this. Alternatively, does anyone know if there's an o-ring in this connection? If so, I may try to just replace the o-ring before I spend $$ on a new radiator and transmission line.

FYI...

if the lines you are looking at go to the drivers side of the radiator then those are for the engine oil cooler NOT the transmission.

Transmission lines go into the passenger side of the radiator.

 

[wjburken]

FYI...

if the lines you are looking at go to the drivers side of the radiator then those are for the engine oil cooler NOT the transmission.

Transmission lines go into the passenger side of the radiator.

I completely missed the “driver’s side” statement.

 

[PoorMansEscalade]

You most likely need a radiator, gm has a bulletin about this. They are blaming the thermostat for the problem. I believe there is

 

[PoorMansEscalade]

You most likely need a radiator, gm has a bulletin about this. They are blaming the thermostat for the problem. I believe there is

There may be special coverage on this. Check with your dealer before you spend money on your own

 

[swathdiver]

I have a 2014 Yukon XL Denali with the 6.2 motor. I recently noticed that there's minor coolant leak/seep from the transmission cooler line, where it connects to the radiator side tank on the driver's side of the vehicle.

Just put a wrench on it and give it a little push. If that doesn't fix it, replace the o-ring or fitting. If that doesn't do it, well then it's time for a new ACDelco radiator. Don't mess with aftermarket unless that Japanese one, Mishimoto or something.

PN# 21742 but double check with @915_Tahoe; give Rene the last 8 of your VIN and he can look it up for you.

 

[muncie21]

Just put a wrench on it and give it a little push. If that doesn't fix it, replace the o-ring or fitting. If that doesn't do it, well then it's time for a new ACDelco radiator. Don't mess with aftermarket unless that Japanese one, Mishimoto or something.

PN# 21742 but double check with @915_Tahoe; give Rene the last 8 of your VIN and he can look it up for you.

Great suggestions. The last 8 of my VIN are: ER158651 It's a 2014 AWD Yukon XL Denali with 6.2 motor

 

[oldchev]

My 2004 Yukon has had coolant leaks at these points twice. I believe the o ring responsible is inside the tank. After looking at the tank securement I felt the chances of further leaks elsewhere where too great and considering the work doing r and r of radiator was enough to just warrant a new radiator. I did that and problem solved for 4 years until it did it again. Seems like problem area. -N

 

[OR VietVet]

I think it is important to note that the lines, on either side, should be secured with a strap or clamp of some sort along the way in at least one place if not at least 2 places so that the weight of the lines is not just dangling where they are routed. Sometimes when work is done and these straps/clamps are removed they don't get put back in place.

 

[915_Tahoe]

Gm#15226661 $6.38 each, takes 2
Trans connectors

O-rings not serviced, part of the connectors.

 

[muncie21]

After multiple washing of the area and inspections, it now looks like the leak/seep is coming from where the plastic tanks are attached to the radiator.

I ordered a Spectra Premium CU2370 radiator (w/oil & trans cooler) from Amazon (~$120/shipped) as I needed the radiator quickly didn't want it to arrive after Christmas. In addition to the radiator, I ordered upper/lower radiator hoses and a new thermostat, since I have easy access to those.

I'm going to install it during the holidays and then check again for leaks. Hoping this fixes the issue and I'm not replacing more hoses afterward.

 

[OR VietVet]

There are threads here about getting the wrong radiator, even though it fits fine, where the coolant return spout to the coolant reservoir tank has a small restriction from the factory and if put in a radiator without that your will have problems with low engine temp, if I remember right.