I'm getting ready to install my mechanical fuel pressure gauge and I'm debating on whether or not I should apply sealant to the male pipe threads. So far my searches have turned up the following products that were used as sealants: Permatex #2; Loctite PTS; plumbers pipe dope; and anti seize. My fuel line connection will be at the bottom of the fuel filter cannister and as a result I'm concerned about possible contamination into the VP44 and/or injectors from the use of any thread sealants. I would like to use a lubricant on the brass threads just to help hand tighten the fittings more securely. If I do end up with a leak, then I might try RectorSeal #5; it's diesel fuel rated and non hardening.

 

I would apply a thread sealant, I use Loctite 567. As long as you do not apply the sealant to the first two threads there is no danger of any contaminants getting into you fuel system. In fact, without the lubricating action of a sealant, galling could produce small flakes of metal from the threads which might find its way into your fuel system.

 

After years of chasing threaded fuel system leaks I've found Permatex #2 to be the best with anti-seize containing soft metals coming in second.
Both are very easy to come by at most autoparts stores.

RectorSeal #5 is my choice for water pipes but I never use it on vehicles.
Big mistake many make with threaded fittings is over tightening. Finger tight with just a couple of wrench turns, more depending on pipe size, is adequate.

 

Thanks george7941 and Infidel for the replies. That's interesting about not applying sealant to the first two threads to avoid contaminants getting into the fuel system. I figured that I would need some kind of lubricant on the threads to prevent galling, that's why I mentioned it in my post. I was thinking more along the lines of 3in1 oil or even engine oil. It would seem to me that Permatex #2 would be a good sealant but not necessarily a good lubricant for the brass threads. Infidel, I'm not disagreeing with you, just speculating because I don't know any better. I would prefer to do this job one time and not have any leaks; especially inside the cab.

 

Permatex #2 has been used in the oil field to successfully seal against petroleum products for many decades. I use it anytime I'm sealing threads against diesel fuel, gasoline, lubricating oil, etc.

Rusty