Correct Sealant on NPT fuel system fittings?

[cleithau]

I am redoing the seal on the fuel system and was wondering what the correct sealant to use on the NPT threads in the fuel filter housing. Liquid teflon pipe sealant or what?

 

[icanfixall]

Just about anything will do but be very careful nothing gets off the threads between the filter outlet to the injection pump. Anything going into the pump can hurt it badly. I like using teflon tape but only use enough to wrap the threads 1&1/2 times. Any more is just wasteful and does nothing for the seal. Remember pipe threads seal by the taper cut on the threads. To understand this look at the pipe threads on any size of pipe or fitting. The starting threads are cut deep but the endind part of the threads are cut shallow. Thats what creates the seal, the threads get tighter the more you thread them together. Also remember never back off the threads if things don't line up. Thghten it one more turn. Otherwise on diesel especially it will leak. The story was if you want to find a leak use water. If that doesn't find the leak use gasoline. If that doesn't find a leak use diesel. If that doesn't find a leak you don't have one.....

 

[Dirtleg]

Loctite 565. I have used it in all kinds of industrial applications at pressures up to 5000 psi. I also used it on the turbo oil line feed and drain threaded connections for my car. Never had any issues at all. It is also rated for fuel use. You can get it at any Fastenal location or order it from Mcmaster-Carr. A small tube is only like $3.

 

[hheynow]

I like using teflon tape but only use enough to wrap the threads 1&1/2 times.

Never use Teflon tape on the fuel system. The smallest piece can easily break off causing a restriction. I suggest Permatex® High Performance Thread Sealant

 

[tonkadoctor]

Never use Teflon tape on the fuel system. The smallest piece can easily break off causing a restriction. I suggest Permatex® High Performance Thread Sealant

+1 there, No tape on fuel OR hydraulics, use a liquid teflon sealant. I use both loctite and permatex brands.

 

[93turbo_animal]

gaseola is what I use its what the pros use on gas and diesel piping for filling stations

also I gotta disagree I've had brand new fittings leak because they were'nt wrapped with enough thread tape on waterlines

 

[icanfixall]

Animal.. If teflon tape didn't seal the pipe fittings you post about then they were not made correctly..... But if you feel more is better thats fine with me. Its happened to me also but these fittings sometimes are made offshore and are suspect at best. Its just a hit and miss thing sometimes.

 

[riotwarrior]

Never use Teflon tape on the fuel system. The smallest piece can easily break off causing a restriction. I suggest Permatex® High Performance Thread Sealant

X 2 for that one, I have used that particular sealant for many years on may things including "Core/frost plugs" fuel fittings, coolant fittings, just bout everything.

 

[MIDNIGHT RIDER]

I suggest Permatex® High Performance Thread Sealant

+1 there, No tape on fuel OR hydraulics, use a liquid teflon sealant. I use both loctite and permatex brands.

X 2 for that one, I have used that particular sealant for many years on may things including "Core/frost plugs" fuel fittings, coolant fittings, just bout everything.

Here is what I have been using with good success :


http://www.permatex.com/products/au..._Permatex_High_Temperature_Thread_Sealant.htm



I am a firm believer in plenty of good old Teflon-tape, for anything else; but, for FUEL systems, it is best avoided.

It is comical to watch people try to wrap Teflon-tape when they don't know how, unless they are supposed to be working on something of mine.

 

[icanfixall]

How true Midnight. There is one correct way but two wrong ways to do it and it sure is funny to watch.... Holding the tape by the spool wrong and it gets longer and longer away from the threads. Put it on the threads backwards and then try to screw on a fitting just unwinds it... Always good for a laugh or two...

 

[93turbo_animal]

Animal.. If teflon tape didn't seal the pipe fittings you post about then they were not made correctly..... But if you feel more is better thats fine with me. Its happened to me also but these fittings sometimes are made offshore and are suspect at best. Its just a hit and miss thing sometimes.

I put in a water line and had 2 brass fittings and I ran out of thread tape after almost 2 wraps but I wanted to get it done so I put it together and ended up having to go back and take it apart cleaned the old tape off and rewrapped it and no more leak so never again will I skimp on the tape for a few cents

 

[MIDNIGHT RIDER]

I put in a water line and had 2 brass fittings and I ran out of thread tape after almost 2 wraps but I wanted to get it done so I put it together and ended up having to go back and take it apart cleaned the old tape off and rewrapped it and no more leak so never again will I skimp on the tape for a few cents

For brass fittings, such as air-lines, etc., I usually count four complete wraps.


For plumbing, such as galvanized water lines, I will go at least five wraps, more sometimes.