[70ElkySS]

I recently redid my whole fuel system and used white teflon paste sealer on all the NPT threads. Within a week, almost every joint had started leaking. When I took them apart, there was almost NO sealer left on the threads. Since I've had good luck with it in the past, I figure it must be because it was old. I just spent the morning re-doing all the threads with Teflon tape. Learn from my mistake!!!:clonk:

 

[Guest]

Get a hold of a Bulk Gasoline Dealer and ask him what kinda pipe dope they use for installing pump nozzles to their hoses b/c the stuff is made for gasoline use!!

It's different stuff than regular pipe dope..

pdq67

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[Motor Martyr]

I use only teflon tape on the NPT threads.

However the majority of my fuel system are AN lines which dont require any sealant.

 

[66 283]

I use the liquid teflon on all NPT fittings and have never had a leak. Teflon tape on nitrous systems is a no-no (or use very sparingly and carefully) as it can get into the solenoid and kill the motor.

 

[Neal Wright]

I'm not a plumber ... but man, I have never gotten pipe dope to work.

Can I ask where you're using pipe dope ... I'm a little slow today, but I can't think of any fittings that are not flared. Flare fittings NEVER use anything but maybe a little motor oil!! Even AN fittings are just another version of a flare.

I haven't put together a nitrous system, but I thought those were all flares also? Again, never tape a flare fitting.

It is true that sealer can cause problems inside NPT fittings. Truefully I've had more issues with plumbers who insist on dope (I hate that stuff). The trick to using tape though ... is to start wrapping from the back end of the threads, always wrap the same direction as turning the fitting, then stop wrapping with about 2 threads bare on the tip of the pipe fitting. This will keep the tape out of any air lines.

Thanks, Neal

 

[Doug Garland]

Work with it every day. We use 2 different kinds, but the name escapes me. The black/grey stuff we use is designed for liquid propane, and sets up extremely hard. It's properties are as such, if in 6 mos. you have to break the parts back down, you have to use a cheater bar. The other type is a yellow/silver, Gas-O-La or something like that. It has teflon in it. I think the black/gray is called John Kline, but not sure.

The only fittings that should need pipe dope are pipe fittings. All others, Flare, etc. should seal off themselves. Occasionally, like 1 out of 90-100 times , I will have to use a dab on a flare, but there is something wrong in the flare, or alignment. The dope isn't as much a sealant as it is a lubricant, to help the threads tighten down deeper in the coupling.

 

[Guest]

Fwiw, My Dad was a Master Plumber back about '60 or so before he died and his cover-alls always had "pink" "pipe dope" on them!!

That's why I call it "pipe dope" is all!!

Flared pipe/tube fittings should NOT need any sealing sort of stuff at all imho if they are flared right!!

SAE or AN or whatever too!!!!!

pdq67

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[Keith Tedford]

All the steel fuel lines on our cars have the flared ends which actually do the sealing The threaded nut just applies the pressure.

 

[70ElkySS]

All the steel fuel lines on our cars have the flared ends which actually do the sealing The threaded nut just applies the pressure.

On a stock one, yes. In my case, there are 14 NPT fittings on the tank sump, fuel filter, Mallory electric fuel pump, Mallory return-style fuel regulator, and Moroso fuel Y-block.

 

[Neal Wright]

In that case, I'd use teflon tape as I explained above ... I really dispise pipe dope

Thanks, Neal

 

[70ElkySS]

In that case, I'd use teflon tape as I explained above ... I really dispise pipe dope

Thanks, Neal

I despise dope now too. Hope the tape holds up!!!

 

[frtupchevy]

I have been a mechanic for 7 years hard and use teflon pipe sealer almost on all gaskets and NPT fittings and found it to work the longest and best. Not so sure why most of you guys are bringing down what worked the best for me. Also considering why does GM use it on head bolts that run into the water jackets, I dont know! maybe cause it works to seal the coolant!!!!! and why has my it never failed me in the trade to seal trans pan gaskets and all other. I guess i just have been lucky?? Ok i will stop using it

 

[70ElkySS]

I have been a mechanic for 7 years hard and use teflon pipe sealer almost on all gaskets and NPT fittings and found it to work the longest and best. Not so sure why most of you guys are bringing down what worked the best for me. Also considering why does GM use it on head bolts that run into the water jackets, I dont know! maybe cause it works to seal the coolant!!!!! and why has my it never failed me in the trade to seal trans pan gaskets and all other. I guess i just have been lucky?? Ok i will stop using it

I wasn't knocking it, just saying I thought that what I used may have been too old. Have you had any experience with old dope not holding up?

 

[SWHEATON]

70 elky,are your lines stainless steel,if yes thats the problem.

The stainless is a little harder material then std steel and it doent like to seal well at all.

I have seen this happen mult times before and when people would replace the stainless with std steel lines & wala all the sealing woe's would disappear,this is esp true for stianless brakelines too.

The stanless lasts longer and looks better but its very hard to get sealled up.

Scott

 

[Dean]

A drop or two of oil on any non pipe thread fittings helps a lot.

Technically (so I was taught) the tapered threads are what are supposed to do the sealing on pipe fittings and only lubrication is needed BUT "pipe dope" sure does help.

Seems like just about every plumber has their own favorite pipe dope but most all of them work just as good as the other.

I've never had teflon paste to "go bad" myself but I have had to stir in a few drops of oil sometimes when it starts to dry up, however I usually use it all up before that happens.

Over the years I've found that one of the hardest type of fittings to get to seal in everyday plumbing repair is brass pipe threads.
I learned years ago to use teflon tape AND pipe dope both to save the time of shutting everything back down, draining the system down and taking the fitting back apart do it over.

I really don't think teflon paste would be good to use on gasoline myself but then I've never tried it, I usually us Pematex form-a-gasket or Indian Head shellack on pipe fittings used for gasoline or oil.

 

[Bob West]

I've always heard that teflon tape is a big no-no in the fuel system anywhere, tends to come apart and clog stuff, filters and needles n seats?