Ladies and gentlemen I need your help, I need to know what the transmission cooler inside of the radiator is made out of I recently had my radiator record and believe they messed up my transmission cooler causing my transmission to fill with antifreeze causing me to need an expensive rebuild.

I believe they failed to pressure test the transmission cooler causing this issue due on their part.

The reason I'm thinking they are at fault is because the desolder the end cap to the radiator to recore radiator they must have overheated the transmission cooler causing the solder to fall off.

 

I can't believe this is happening to me I'm seriously sick to my stomach

 

Well I have an X300 XJR and the radiator end tanks appear to be plastic (or composite) so soldering would not be an issue. Was the radiator rebuilt with the original end tanks or replaced complete?

 

The radiator core would not originally have been soldered, as it is aluminium, and the end "tanks" plastic. The ends are crimped on, and I suspect your recited radiator is the same. Inside the end tanks are metal heat exchangers connected to the transmission on one side, and the power steering on the other, to cool their respective fluids. The weak spot is the connections between the metal connectors on the tanks and the pipes connected to them. If the pipes are over tightened, the torque is not supported by the plastic tank, and is transmitted to the heat exchanger which is really not up to it, and tears at the connection, creating a leak between the coolant and the fluid. I managed to achieve it on the power steering side when undoing the connection, due to some sort of electrolytic corrosion between the pipes and the connector.
Is it possible you overtightened a pipe when reconnecting it?

 

My ends are not plastic

 

Then it sounds like you may have a non standard radiator. Not in itself an issue, but makes it difficult to offer any advice I'm afraid, without knowing more about it. Any pictures?