Teflon tape on 4L60e coolant line connection, good or bad idea?

[Ardent_Z28]

I sprung a minor leak on the coolant return line and replaced the brass fitting on the tranny. Before I hook the line back up I am tryin' to find out if applying teflon tape to the coolant line fitting's threads would be a good idea.

[SSlowBoat]

Indian head shellac works better, teflon breaks down with oil. Technically its a dry fitting since its a flare

[firebird_1995]

Bad idea. Like shawn said, its a flare fitting, and nothing should be used on it. Using any kind of sealant or tape could actually cause it to leak instead.

[SSlowBoat]

shellac is made for threaded connections. little did i know ive been using the stuff for atleast 5 years at work, in a generic bottle, on high pressure refrigeration flare fittings and compressor rebuilds.

but yes, nothing really should be used on it since its a flare fitting. there is a happy medium with a flare, must be good and clean, no burrs, and tight but not over tight.

[CPT]

We use Permatex "Ultra Copper" silicone on the threads. I've seen teflon tape break the cases.

Frank

[Ardent_Z28]

Well I tried the Permatex route cuz the Indian head shellac had to be applied to both sides of the connection. IMO it wasn't a good idea to apply it to the brass fitting on the case cuz it could squeeze inside the line, especially since I had clearance and line of sight issues tryin' to apply it. It slowed the leak way sown but didn't stop it. I have a spare coolant line that has already been cut and spliced with a hose and clamps so I may use the end of it to replace the leaking end on my car. If I do that I intend to cut the leaking end on the car the same length as my spare so I can butt up the ends inside a piece of hose and clamp it off. With this idea I can try to dry fit it first and see if the leak stops. I appreciate the feedback fellas, it was worth the try and may still work yet and am still open for suggestions. I'm gonna stop the leak so I can get on the track...hell they don't want anyone's A/C running in the staging lanes cuz it will sweat onto the track!!

[Ardent_Z28]

Went with cutting the line and installing my spare fitting. Butted the ends in a piece of hose, clamped it at the butted joint as well as both ends of the hose. The fitting is put together dry...no permatex. Cranked the car while still on the blocks and no leaking. Let it sit overnight and cranked it and still no leaking so I put everything back together and put 'er on the ground. Drove it about 4 miles and parked it...still no leaks. The next day I drove it 2 miles and checked the fluid level...added about half a pint until it was into the HOT crosshatches. Then...the leak started again. I'm tqakin' a break from it for now...my back is killin' me from layin' on my driveway and gettin' up and back down repeatedly. I'm glad it isn't my daily driver and can take my time with this.

[Ugod02010]

Hate those pain in te ass leaks. Never easy to get to, and just drive u nuts in general. Just a thought but it's not the trans filler that could be leaking. I had an issue with a older Camaro I had I thought it was the cooler lines leaking and it ended up being the filler, after fighting those lines for a week. That little rubber gasket deteriorated and started leaking.

[Ardent_Z28]

I know it's the coolant line for sure. There's a pit between the rails in the locomotive shop where I work. When the leak started a couple months ago I pulled my car onto it, cleaned the area, and watched it leak as it idled over the pit. I attached a short hose to the overflow tube on top of the tranny and ran it down past the pan when I installed it in my car...just to eliminate future guessing if a leak or overflow was coming from there. While I had it on blocks I did check that piece ya mentioned while the car idled, as well as the case over the fittings just to be sure it wasn't running down from above 'em. My wife suggested I try the FlexSeal from the TV commercial a guy used to fill holes drilled in a plastic bottom boat. I laughed but, ya know, that may be a good suggestion!!