I had a similar experience with the fittings on injector lines on an old VW Pickup with the 1.6l diesel. It appears that it happens from age. The lines were replaced and there have been no problems related to this again.

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Jovan

'84 (11/83) 190D 2.2 5-Speed; Silver/Blue; Motor No. 00354, 402k mi (340+kmi mine)

'89 Porsche 911 Turbo Coupe; Black/Black; 53kmi
'05 BMW 530i 6-Speed; 302kmi
'19 Range Rover; 30kmi