Thread Sealant

[RJ]

All -

What type of sealant (if any) is recommended for diesel fuel line fittings?

I've got a leak coming off the secondary fuel filter where there's a sending unit screwed into the filter housing.

It's not the sending unit itself, it's coming out between the housing and the NPT sender's fitting.

Yes, it's tight.

Suggestions?

TIA

[luvrbus]

Permatex #56521 or 80632 a little pricey for 4 oz but it works, both are same except the 56521 will harden , NAPA house brand is the same I have used all 3

[chessie4905]

You sure the housing doesn't have a small crack? Or the pipe thread is worn big and fitting bottoms before getting sealing tite