Help ID this Leak

SmokeShow

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Nov 30, 2006
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See picture. Does it appear the hard line is leaking. It feels snug with a wrench. I'm not even sure what that line is? Is it a coolant line or trans line? I suspect coolant because of an apparent warm antifreeze smell when I get out & trans frlluid level never goes down. Have notice a loss of coolant either though. It leaves a drip spot about the size of a kiwi or maybe baseball. It seems to leak a fair bit onto the pass. side brake & auses it to slip & consequently pull to the driver's side because that sides working properly.

Thoughts?

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SmokeShow

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Is there supposed to be an o-ring there & maybe its shot? Or should it seal up with the fitting snugged up (which it is) & therefore have something else going on?

If its the connection that's bad, would new lines or new cooler or both be advised?

Cooler is inside the radiator, not in front? How does one abandon that if they run an aftermarket unit like Mike's?
 

TheBac

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Apr 19, 2008
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Yep, theres an oring on those fittings where they screw into the radiator. Its possible the oring went bad. BTW, the pipe/hose is held in by a wire clip.
 

blk smoke lb7

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The fluid runs through the rad 1st then through the trans cooler infront of the stack then back to the trans.Spray it off with brake clean and see if its leaking from where the line inserts into the rad fitting or if its seaping out from where the rubber hose is crimped to the aluminum end.If its at the fitting try the o ring if its at the crimp you need new lines.Edit went back and looked at the pic closer theres no crimp end near there try the o ring and see if that fixes it.
 

SmokeShow

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Ok, does anyone know if it's a standard size and type of o-ring that may be redily available or am I going to have to try to source it from the GM dealership?
 

Chevy1925

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Ok, does anyone know if it's a standard size and type of o-ring that may be redily available or am I going to have to try to source it from the GM dealership?

i tried a generic one, started leaking not long after doing it. id get a GM one but they may only sell you the whole screw in fitting (the part that the steel line inserts into actually screws into the radiator there). Mine looks just like yours lol
 

durallymax

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His truck is different than all of ours guys. He has an early one so it still uses the old style NPT fittings. As far as what is behind the fitting that holds the trans cooler in the radiator tank I do not know, could be an o ring like the older ones but what I do know is that it is not the single piece design like all of the later ones. You can clearly see it in the picture.
 

Chevy1925

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His truck is different than all of ours guys. He has an early one so it still uses the old style NPT fittings. As far as what is behind the fitting that holds the trans cooler in the radiator tank I do not know, could be an o ring like the older ones but what I do know is that it is not the single piece design like all of the later ones. You can clearly see it in the picture.

Its the same as mine Vinny. i have an 02 ;) :D. the only o-ring i replaced was the one inside the fitting the trans line seals against. ive yet to pull the fitting out of the radiator
 

durallymax

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Its the same as mine Vinny. i have an 02 ;) :D. the only o-ring i replaced was the one inside the fitting the trans line seals against. ive yet to pull the fitting out of the radiator

The 2001s and the very early 2002s used NPT fittings. Later 02s were different but you say you've never had that part out anyways.

The O-ring inside the fitting just seals ATF. the O-ring behind the fitting on the later trucks is what seals the fitting itself to the cooler because they are straight thread o ring seal fittings. The early trucks use NPT thread fittings which will still have an o ring inside to seal the ATF but use the threads for sealing otherwise.
 

SmokeShow

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Vinny, you're convinced that's npt style fitting so I just need to get oring for inside the fitting then, right?

Would someone with an 03+ mind throwing up a pic of theirs to verify mines different?
 

durallymax

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Shoot I was gonna take a picture for you. If its leakibg coolant I am not sure what you need I cant remember what is under thr fittibg that the trans line fitting screws into.

The way to verify it is to look at both of thr fittings. The newer style will just have a silver domed washer under the trans line fitting. The older style will have a brass hex fitting that the trana fittibg screws into. It looks like that style in the picture.

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