New radiator installed - trans fluid leaking out the cooler line fittings.

[SteveRosenow]

So I picked up a new radiator today, as part of a warranty replacement through O'Reilly. After installing the transmission cooler lines and filling the radiator with 50/50 coolant, I tested the connections and for leaks and sure enough, I ended up with a whopper of a leak out of the top fitting. It is enough to create a steady stream of transmission fluid that leaks both down the side of the radiator and down the right hand side of the fan shroud. It also contacts the fan itself and I have a nice stain of Mercon V on the underside of my hood and all over my freshly-detailed engine bay.

I noted in one YT video that these fittings should be installed with PTFE thread tape, and to be sure the new radiator did come with two brand new fittings, in the event that the ones installed on the radiator do not fit my cooler lines.

This is my only rig, and with the severity of the leak I cannot afford to drive it the nine miles to my work (O'Reilly Auto) to have this second radiator warranty-exchanged.

What could fix this leak besides a second warranty exchange?

 

[Mr. Alligator]

Did you use thread tape?

I did not see any thread tape.

 

[donalds]

There is suppose to be a o ring in there look in your old rad

 

[SteveRosenow]

Did you use thread tape?

I did not see any thread tape.

No, I didn't use any however I do have a few rolls of it.

I also note that it had been used on the previous radiator straight from the factory.

 

[SteveRosenow]

There is suppose to be a o ring in there look in your old rad

No O-ring present in both upper and lower.

 

[donalds]

Hmmm that's weird add one

 

[donalds]

A pic

 

[974X4BLACKSPORT]

The adapter going into the radiator must have thread tape on it, just like the factory ones had on them (at least mine did).

 

[Mr. Alligator]

Looks like you need Teflon tape AND o-ring. Not sure which is more important (probably the o-ring), but I would be confident that if you use BOTH, you will not lose fluid.

Good luck.

 

[koda2000]

I've never had to use Teflon tape on my Explorer/Mountaineer radiators (and I've replaced a bunch of them). There should have been O-rings on rad and adapter as pictured by @donalds. I might be wrong, but I don't think any of the rads I installed had adapters, the trans lines just screwed directly into the rad.

 

[SteveRosenow]

As a side note...

Has anyone ever replaced a radiator (which involved thermostat replacement as well as a cooling system flush) only to have the water pump start leaking?

That happened to me and I swear I just want to be done with this nightmare!

 

[koda2000]

As a side note...

Has anyone ever replaced a radiator (which involved thermostat replacement as well as a cooling system flush) only to have the water pump start leaking?

That happened to me and I swear I just want to be done with this nightmare!

Sometimes the only thing that's preventing cooling system leaks is the crud in the system. Yes, I have experienced various cooling system leaks after flushing and replacing the antifreeze. If it's been a few years since you've replaced cooling system parts it's a good idea to consider replacing the hoses, t-stat, water pump and radiator cap along with the radiator and flush. Yes it will cost you more, but not replacing the other parts is the equivalent of crossing your fingers.

 

[SteveRosenow]

Sometimes the only thing that's preventing cooling system leaks is the crud in the system. Yes, I have experienced various cooling system leaks after flushing and replacing the antifreeze. If it's been a few years since you've replaced cooling system parts it's a good idea to consider replacing the hoses, t-stat, water pump and radiator cap along with the radiator and flush. Yes it will cost you more, but not replacing the other parts is the equivalent of crossing your fingers.

The radiator and thermostat was already replaced.

 

[donalds]

T stat
radiator
upper radiator hose
lower radiator hose
All 4 heater hoses
Water pump
Radiator cap
Flush the heater core thoroughly
And if your feeling squirrelly a nice new motorcraft water pump
And NEW coolant

What I did Fix it the right way only one time just my 2¢