sealing fuel tap (petcock) thread

[desros]

Am installing new fuel taps (petcocks) to replace leaking taps and wonder if any tips of what can/should be used to apply t thread to seal (gas resistant) the thread so no leaks.
Thanks.

 

[Marathon Man]

Here's what I used. THE best. I found 'em on eBay:

 

[BrianK]

Simple copper washers work fine. I anneal them each time I remove and reinstall the petcocks - 5-10 seconds with a propane torch does the trick.

 

[DogT]

I used some stat-o-seals I got from walridge, and they worked on my originals, but not on the BAP I got from OB. I ended up sealing them with Permatex Aircraft gasket sealant and the stat-o-seals. I'm sure there are other options.

Dave
69S

 

[72westie]

Go to NAPA and get some drain plug washers that have the rubber seals in the middle. I think they are like 1.50 each and use a washer in between the drain washer and the petcock nut. I found some aftermarket blade style petcocks that have longer threads that help accommodate the two washer setup.

 

[desros]

Dave.
What is BAP from OB?
Ron

 

[old-grizz]

I have tried many combinations of everything, but what finally worked for me was a heavy-duty PTFE sealing tape I got for about $5 a roll at Ace Hardware. It is in the plumbing/piping section and is used mainly for sealing natural gas lines in homes. The roll I got was yellow - don't know if they are all that color. Anyway- if you read the package carefully it will say words to the effect of "gasoline proof". An application of this stuff on the petcock threads cured a leaking/oozing problem I had been fighting on and off for years.

Good luck -

-O.G.

 

[DogT]

BAP is an Italian brand of petcock, and OB is Old Britts.

Dave
69S

 

[drones76]

Go to NAPA and get some drain plug washers that have the rubber seals in the middle. I think they are like 1.50 each and use a washer in between the drain washer and the petcock nut. I found some aftermarket blade style petcocks that have longer threads that help accommodate the two washer setup.

Just a quick followup because I was having a heluva time finding these without having to pay more for shipping than the washers. The local NAPA had them. The guy was busy so he pointed to the shelves in the stock room and let me root through them. I found what I was looking for. Napa part number is 704-1953 $1.99 each.

 

[swooshdave]

Go to NAPA and get some drain plug washers that have the rubber seals in the middle. I think they are like 1.50 each and use a washer in between the drain washer and the petcock nut. I found some aftermarket blade style petcocks that have longer threads that help accommodate the two washer setup.

Just a quick followup because I was having a heluva time finding these without having to pay more for shipping than the washers. The local NAPA had them. The guy was busy so he pointed to the shelves in the stock room and let me root through them. I found what I was looking for. Napa part number is 704-1953 $1.99 each.

Thanks, I knew NAPA had them, but I didn't know the part number.

 

[daveparry]

As OG says, ptfe tape does the trick, btw here in England the yellow ptfe is the gas version. (not gasoline but gas we use for heating boilers and cookers etc)

Dave.

 

[comnoz]

As OG says, ptfe tape does the trick, btw here in England the yellow ptfe is the gas version. (not gasoline but gas we use for heating boilers and cookers etc)

Dave.

Agreed, 6 or 8 wraps of PTFE or Teflon thread tape around the threads above the jamb nut seals then permanently.
If you have the type of petcocks with the jamb nut, the stat-o-seals or copper washers do no good. Jim

 

[mikegray660]

make sure if you use the tape you have some type of fuel filter - preferably to prevent from getting into the petock inside the tank

on the web -

""Backyard mechanics will tell you they've used regular old gas resistant teflon tape (yellow stuff) with success. This is not recommended because it risks breaking free. Liquid or paste type thread sealants are kinder to sensitive components down stream. Mechanics repairing injectors, fuel pumps and carburetors can tell you first hand it is not uncommon to trace fault in the fuel component to clogging from a piece of teflon tape that washed off the ends of the threads, clogging in the first tiny micron orifice it encounters, if not the fuel pump then an injector or carburetor gallery. Either way it's a costly repair. Liquid or paste type sealant won't clog. For gasoline, regular old gasoline resistant Aviation Form-a-gasket Number 3 is the best option. Another product also offered by Permatex is the High Temperature Thread Sealant. Tech data on this sealant says it has medium solvent resistance and is recommended for fuel sender type applications. With the advent of ethanol present in modern gasoline, I favor Form-a-gasket No. 3 which specifically states solvent resistance to gasoline, especially on modern engines that use injectors rather than carburetors such as the E-TEC and HPDI (high pressure direct injection) and any diesel engine""

 

[comnoz]

Not a problem as long as you wrap the threads withoul letting it hang off the end. Of course I wouldn't run without a fuel filter anyway. Jim

 

[DogT]

I found, like Jim said, that stat-o-seals don't work with petcocks that have the jam nut. I put some Permatec Aviation form-a-gasket (80019) on the threads and that seems to have done the trick for me. I have the BAP taps from Old Britts.

Dave
69S

 

[L.A.B.]

I found, like Jim said, that stat-o-seals don't work with petcocks that have the jam nut.

The copper/rubber type as shown in Anglophile's photo always worked 100% for me, and they are what most UK parts suppliers sell, but they do need a plain washer between the nut and the sealing washer.

 

[DogT]

..but they do need a plain washer between the nut and the sealing washer.

I'll try that the next time they come off. Thanks.

Dave
69S

 

[comnoz]

I found, like Jim said, that stat-o-seals don't work with petcocks that have the jam nut.

The copper/rubber type as shown in Anglophile's photo always worked 100% for me, and they are what most UK parts suppliers sell, but they do need a plain washer between the nut and the sealing washer.

Yes I am aware of that, I have a bin full of them. Any time I tried to use one without sealant I ended up with brown stained petcocks so I just throw them in the bin and use thread tape. I don't know how the sealing washer would be expected to seal against the threads. Jim

 

[L.A.B.]

Any time I tried to use one without sealant I ended up with brown stained petcocks so I just throw them in the bin and use thread tape. I don't know how the sealing washer would be expected to seal against the threads. Jim

Is that the copper type?

When the copper/rubber sealing washer is compressed, the rubber is forced tightly into the threads (but it should be tight to start with) so I don't see how you can't get them to seal?
When correctly tightened (with the plain washer between the nut and seal) they don't leak or allow any staining at all.
I found alloy Stat-O-Seals were too soft and tend to crush far too easily, and 'Dowty' seals do not seem to work as well either although they have a bonded insert they are not crush washers.

 

[comnoz]

Any time I tried to use one without sealant I ended up with brown stained petcocks so I just throw them in the bin and use thread tape. I don't know how the sealing washer would be expected to seal against the threads. Jim

Is that the copper type?

When the copper/rubber sealing washer is compressed, the rubber is forced tightly into the threads (but it should be tight to start with) so I don't see how you can't get them to seal?
When correctly tightened (with the plain washer between the nut and seal) they don't leak or allow any staining at all.
I found alloy Stat-O-Seals were too soft and tend to crush far too easily, and 'Dowty' seals do not seem to work as well either although they have a bonded insert they are not crush washers.

The washers that have been supplied with the petcocks I have bought here look like the common stat-o -seals. A steel washer with a bonded rubber insert in the center. They have always leaked slowly when I used them without sealant. I have some that appear to be a copper washer with a bonded insert but I don't think I have ever tried using them without sealant. Many years ago I started using thread tape and tossing the washers in the bin and have had good luck so I haven't tried any more sealing washers. I just save them for banjo fittings and drain plugs. Jim