Fuel Line
- Thread starter raffaelli
- Start date
lateapex911
Super Moderator
Smarter builders will hopefully chime in here, but I use teflon tape. I wrap it "with" the threads, if you know what I mean, although I think it's OK either way. I try to get 3 wraps, and I always start up a thread or more. I do this because I don't want any loose bits hanging in the fuel stream.
keep in mind, this is based on "Jake logic" which has NOTHING to do with established practices, LOL.
Because I use that unrecognized form of logic, I place a couple of good fuel filters in strategic locations. So make sure you have one downstream of this connection.
keep in mind, this is based on "Jake logic" which has NOTHING to do with established practices, LOL.
Because I use that unrecognized form of logic, I place a couple of good fuel filters in strategic locations. So make sure you have one downstream of this connection.
titanium
New member
When looking at a fitting and trying to decide if a thread sealer should be used, you need to look at where the 'seal' on the fitting is located.
1) If there is a mechanical seal on the fitting, like an O-ring or washer, then no additional sealer is required.
2) If there is a flare or inverted-flare on the fitting, like an AN or brake line, then no additional sealer is required.
3) If the threads of the fitting are designed to do the sealing, then you should use Teflon tape or paste.
In the fittings that you have pictured, the one on the left looks like it has an O-ring on the end. No tape needed.
In the fitting on the right, it looks like there is an inverted flare on the end. Again, no tape needed.
Rule of thumb:
A pipe-thread (tapered thread) fitting will always require a thread sealer.
A straight-thread fitting will not require a thread sealer.
As with all rules of thumb, there will be exceptions. I have seen aftermarket fuel pumps that were provided with pipe-thread barb fittings that said in the instructions to not put sealer on the threads. I followed the instructions and the fittings didn't leak!
(Fuel pump manufactures worry that a piece of Teflon tape will tear off a fitting and get ingested by the pump)
I'm not sure if I helped but there you go!
1) If there is a mechanical seal on the fitting, like an O-ring or washer, then no additional sealer is required.
2) If there is a flare or inverted-flare on the fitting, like an AN or brake line, then no additional sealer is required.
3) If the threads of the fitting are designed to do the sealing, then you should use Teflon tape or paste.
In the fittings that you have pictured, the one on the left looks like it has an O-ring on the end. No tape needed.
In the fitting on the right, it looks like there is an inverted flare on the end. Again, no tape needed.
Rule of thumb:
A pipe-thread (tapered thread) fitting will always require a thread sealer.
A straight-thread fitting will not require a thread sealer.
As with all rules of thumb, there will be exceptions. I have seen aftermarket fuel pumps that were provided with pipe-thread barb fittings that said in the instructions to not put sealer on the threads. I followed the instructions and the fittings didn't leak!
(Fuel pump manufactures worry that a piece of Teflon tape will tear off a fitting and get ingested by the pump)
I'm not sure if I helped but there you go!
Last edited:
tom_sprecher
Super Moderator
+1 for titaniums reply except I tend to always use a thread sealant on pipe threads. Use a a liquid form of teflon sealant and keep it away from the first couple of threads to keep it from getting ingested by the system being sealed.
lateapex911
Super Moderator
Disagree, guys.
The left fitting is the actual port. The hose goes on the non o ring end, and the assembly gets pushed in, releasing fuel. The O ring is the seal/break part of the port.
The other barbed fitting does have a chamfer, but thats not a sealing surface, unless there were a matching surface in the junction block thats shown, but there isn't.
here's the link for the page the products are on.
http://www.pegasusautoracing.com/productdetails.asp?RecId=3447
The threads are all listed as 1/8" NPT.
So, the threads will do the sealing, not the mating surfaces. Sealant needed.
The left fitting is the actual port. The hose goes on the non o ring end, and the assembly gets pushed in, releasing fuel. The O ring is the seal/break part of the port.
The other barbed fitting does have a chamfer, but thats not a sealing surface, unless there were a matching surface in the junction block thats shown, but there isn't.
here's the link for the page the products are on.
http://www.pegasusautoracing.com/productdetails.asp?RecId=3447
The threads are all listed as 1/8" NPT.
So, the threads will do the sealing, not the mating surfaces. Sealant needed.
tom_sprecher
Super Moderator
Your are correct. The +1 was for titanium's "rule of thumb". I must have skimmed over his comments on the pictures above. They appear to all be NPT and therefore no O-rings are used. Sealant is necessary. Batteries not included. The results are not typical. Some assembly required. If symptoms persist see your doctor. Etc, etc, etc.... 
Thanks fellas.
I went to Autozone to get some Permatex thread sealant and some new fuel line. I spoke to the 'head guy in charge' about what I was doing. He said there was no such thing as fuel resistant sealants and I will contaminate the system. He suggested making the threads tight enough The Permatex I bought says it can be used on diesel lines.
I will assemble this thing with the sealant I bought on just upper threads as you have suggested. Jake, great idea about the filter. I will add one. I am going to install the port and new filter on the return line between the fuel rail and the fire wall. It seems to be the easiest, low congestion place to install it.
I went to Autozone to get some Permatex thread sealant and some new fuel line. I spoke to the 'head guy in charge' about what I was doing. He said there was no such thing as fuel resistant sealants and I will contaminate the system. He suggested making the threads tight enough The Permatex I bought says it can be used on diesel lines.
I will assemble this thing with the sealant I bought on just upper threads as you have suggested. Jake, great idea about the filter. I will add one. I am going to install the port and new filter on the return line between the fuel rail and the fire wall. It seems to be the easiest, low congestion place to install it.
Gotta love the knowledge that gets dropped on ya at the 'Zone! 'Head up his rear guy in charge'?
Technical Data Sheets for standard Permatex thread sealant and Loctite 565 both list them as chemically resistant to gasoline. FWIW the only thing I use tape on anymore is household water plumbing. I use PST on just about everything. It works real well on brake bleeder threads too. If you're trying to use a siphon type bleeder they can pull air around the threads and make you think all those bubbles you're seeing are coming from the caliper. 
http://www.permatex.com/documents/tds/automotive/56521.pdf