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Richhh · 13-09-2005, 11:20

NOTHING should be used on fuel line threads.

Most boat builders use cheapy 'compression' fittings that are quite inferior to a standard flared union. Normal vibrations, etc. on a boat will cause the compression nut/ferrule inside a compression fitting to compress and deform the soft copper tube ... hence the leak and no matter how tight you run up the threads. Actually such compression fittings are for ONE TIGHTENING ONLY and should be replaced every time you loosen a fitting - the tube should be cut and a new compression ferrule installed.

Flared fittings (double flared is preferred) using stainless steel tube is the SAFE way to make such a connection. Flare tools are cheap - just takes some 'expertise' to use one.

FYI - copper is INCOMPATIBLE with fuel oil - it accelerates the 'ageing' process of the oil.

hope this helps.

13-09-2005, 11:20	#4
Richhh Registered User Join Date: May 2005 Location: Pennsylvania Boat: Tayana 37, M-20/I-20 Scow Posts: 250	NOTHING should be used on fuel line threads. Most boat builders use cheapy 'compression' fittings that are quite inferior to a standard flared union. Normal vibrations, etc. on a boat will cause the compression nut/ferrule inside a compression fitting to compress and deform the soft copper tube ... hence the leak and no matter how tight you run up the threads. Actually such compression fittings are for ONE TIGHTENING ONLY and should be replaced every time you loosen a fitting - the tube should be cut and a new compression ferrule installed. Flared fittings (double flared is preferred) using stainless steel tube is the SAFE way to make such a connection. Flare tools are cheap - just takes some 'expertise' to use one. FYI - copper is INCOMPATIBLE with fuel oil - it accelerates the 'ageing' process of the oil. hope this helps.