Transmission cooler line leak

[myk]

After I replaced my radiator I've noticed a Trans cooler leak that's progressively getting worse; I'm pretty sure it's the joint between the fitting and the line.  I tried removing and replacing the line and tightening the nuts but the leak continues.  Is there supposed to be an o-ring or something inside of the fittings?  Is this an indication of the fitting or the line damaged?  I've read that you have to use plumber's tape while others are sworn against it.  Any suggestions?  Thanks guys...

[WHITE AND RED 69]

If I remember correctly the stock lines are flared so your leak is at the seal not on the threads. So tape or thread sealant won't stop the leak. Since you already swapped out the lines, my guess would be the fitting on the radiator isn't fully sealing against the flare on the cooler line?

Did you get new fittings when you bought the radiator? Or did you use the old ones?

[ws23rt]

I agree that the seal is at the flare.--For what it's worth-- the leaking issues I've had with flare connections are usually when the tube does not line up real well before tightening. A small out of misalignment is a lot to ask from that little threaded connector ---It's job is to compress the flare not to bend the tubing as well. --BTW adding any kind of sealer to the flare is not a good solution.

[myk]

I reused the old fittings, moving them to the new radiator.  I'll look into the fittings themselves, although where would I get new ones?  Are they readily available at parts stores?

I take it you guys aren't using flared lines on those lines anymore?

[ws23rt]

I am seeing a bit of confusion here.---A tapered/pipe thread connection is the first on the radiator.

If your leak is at that point ---a thread sealer is in order.---Those threads (tapered threads) are where that seal is made.

That part is a pipe to flare adapter fitting. If their is a question about that adapter you can take one of them to auto parts to match it up. My bet is what you have is ok but just needs to be carefully cleaned and use pipe thread Teflon paste sealer on the threads. The flare connection from the line connects to that adapter fitting.

[WHITE AND RED 69]

I take it you guys aren't using flared lines on those lines anymore?

No flared fittings for me, I have swapped everything on my car over to AN fittings.

[ws23rt]

I take it you guys aren't using flared lines on those lines anymore?

No flared fittings for me, I have swapped everything on my car over to AN fittings.

Your first connection on a stock radiator is still a pipe thread. -- I to prefer AN fittings---they are a better flare type connection.

[WHITE AND RED 69]

I take it you guys aren't using flared lines on those lines anymore?

No flared fittings for me, I have swapped everything on my car over to AN fittings.

Your first connection on a stock radiator is still a pipe thread. -- I to prefer AN fittings---they are a better flare type connection.

Yup, NPT in the radiator (with thread sealant) and -6 AN to the cooler lines.

[birdsandbees]

They're still "flare fittings". AN are 37 degree.. automotive standard is 45 degrees.

So is the leak on the fitting to radiator, or coming out of the nut on the tubing.

Best thread sealer is PST-592 by Loctite. I use it on every aircraft fitting I install for fuel or hydraulics. Never have had a leak.

If it's coming out of the "nut" then you probably have a burr or a crack on the tube flare. Over tightening is usually the cause of a crack.