The steering rack of my Volvo 780 leaks at the line that feeds the rack from the pump at the psg side, see photos. I tried to tie it but it keeps on spinning when it comes to the end, it won't lock.

I loosened it up entirely to see what's going on and to clean the treads. At the top there is a small O ring that I will replace. Besides the O ring can I use something like Permatex High Temperature Thread Sealant with a fitting like this? Or any other suggestions to make it from leaking?

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).