Thread sealant for diesel fuel lines?

Sep 30, 2013
3,538
1988 Catalina 22 North Florida
I have Permatex aviation form-a-gasket #80019, and Permatex thread sealant #80632 on hand, as well as some petroleum-resistant teflon tape. But the instructions on my new Racor filter say not to use tape.

What do the wise old salts recommend??
 
Jun 2, 2004
3,390
Hunter 23.5 Fort Walton Yacht Club, Florida
The seal is at the end of the line not at the threads, however I put one wrap of Teflon tape on fittings just to make it easier to come loose when needed. May not be necessary just habit.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
The issue with tape is not all of it will be captured in the threads and small amounts may enter the fuel system clogging line and fuel filters.
 
Aug 22, 2017
1,609
Hunter 26.5 West Palm Beach
Mako Hose & Rubber in West Palm Beach is my go to shop for anything to do with fuel lines, including filters, pumps, fittings, & making threads seal. They carry fuel specific dopes for sealing threads. They generally carry more than one type of dope for most fuels. A quick chat with those guys will get you the info that you need. I have always purchased from them face to face, but there is a good chance that they will also do mail order.

A very small spec of crud in the fuel system is enough to clog an injector. Be sure to apply Diesel dope correctly.
 
Jan 5, 2017
2,263
Beneteau First 38 Lyall Harbour Saturna Island
@Gene Neill your racor is on the low pressure side of the fuel system usually brass to steel so self sealing. The high pressure side is normally steel to steel without any dope etc.
 
Aug 22, 2017
1,609
Hunter 26.5 West Palm Beach
Also, fyi, Real diesel & bio diesel have different solvency properties. Neoprene is my go to seal material for real diesel. It does not hold up to bio diesel well at all. It swells & softens when exposed to that stuff, then shrinks & leaks when you go back to real diesel. I am sure that there is a biodiesel compatible material out there, but I would need to look up what it is.
 

capta

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Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
I still use the old Permatex® Indian Head® Gasket Shellac Compound that I've always used, for both gas and diesel. I really don't think there's anything better, it's cheap and it has never once failed, yet it comes apart easily. A 2oz bottle lasts forever! Thread tape is not recommended for fuel lines, mainly because bits can get into the fuel system and......
indian head.jpg


For really difficult seals, Permatex Form-A-Gasket No. 2 Sealant (3 oz.) always does the job for non-food grade connections.

 
Last edited:
Sep 30, 2013
3,538
1988 Catalina 22 North Florida
Permatex® Indian Head® Gasket Shellac Compound that I've always used, for both gas and diesel. I really don't think there's anything better, it's cheap and it has never once failed, yet it comes apart easily. A 2oz bottle lasts forever!
Good enough for me! One click at Amazon, $3.22, it will be here in 48 hours. Thanks! :beer:
 
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