hi , i took off Transmission cooling lines from the radiator of my 2004 jaguar s-type and I damaged both the hole in the radiator ( was not bad ) and the bolt from the Transmission cooling lines , if I want to rethread the bolt my question is what is the spec of it ( the threading) , it look like its an M18*1.5 . any help
thanks , pics are attached

 

see if you can find another steel nut of the same thread and gently use it to clean the thread of the Male part of the connector, then use a bolt of the same thread and clean the female union on the radiator. There should be an O ring on the male part of the pipe.

 

No idea on the thread size or pitch. I know some of the big box auto parts stores carry new female radiator connectors. As for the male you may have to cut apart, slide a new male on and use a small rubber hose and radiator clamps to reassemble. That or purchase new radiator lines and have fun installing them.

 

To build on this excellent advice, cut the nut in half and then reassemble the two pieces over the damaged male threads. Lightly clamp the two pieces in a vise and use a wrench to unthread the fitting. As you unthread it, the cut edges of the nut will help clean up the damaged threads.

The big advantage to this method is the risk of crossthreading is almost eliminated, as the female threads will engage undamaged threads away from end of the fitting.

 

this method looks complicated to me

 

If there is enough of the metal left on the female part of the union, use a tap to chase and restore the threads. The male connector can be cleaned up using a die of the correct pitch.

You should also use teflon tape to keep the threads sealed and prevent them seizing together. Also, torque the fitting to the specification so it's not over tightened.

 

You can buy spark plug "thread chasers" in 18mm size but you need to find out the correct thread gauge is it 1.5 or 1.25 etc?

 

the problem is more with the pipe bolt, I couldn't reach it because of the pipe circle, in the beginning, i tried a die 18mm and 17mm ( ) but can't, but for the radiator thread i have too many methods and the easy one is tap it with 17mm tap

 

and the bolt doesn't have a parallel threading, it a not a strait bolt , start with 17mm and finish with 18mm ,

 

its 1.5

 

finally i just bought a used Transmission cooling lines from ebay , and try to change the whol line , thanks to all

 

Why used? For all the work your going to need to do you should install new lines. No guarantees those lines are good.