Thread Sealant on Banjo Fittings?

[Midnight Specialist]

Does anyone know if the banjo fittings for the fuel lines need any sealant or is the copper washer sufficient?

[Helirich]

Copper washer is sufficient. But you may need a new one. I suggest you buy an assortment of metric washers from the bay. The metric sizes are harder to come by and can sometimes be expensive. The big assortment I bought was dirt cheap and had many of most sizes that we use.

[Michael]

Copper washers are designed to be used only once. Any more and you have to torque them tighter(and on a 10mm banjo you don't want to do that).

Never put teflon tape or any of that junk on it as the gas will dissolve it and either cause a leak or push it through your fuel system.

[Helirich]

Copper washers are designed to be used only once. Any more and you have to torque them tighter(and on a 10mm banjo you don't want to do that).

Never put teflon tape or any of that junk on it as the gas will dissolve it and either cause a leak or push it through your fuel system.

While I agree, do not put Teflon tape on the threads of banjo bolts, gas does not dissolve it. There is no reason to put it on banjo bolts because they are not sealing anyways.

[Michael]

While I agree, do not put Teflon tape on the threads of banjo bolts, gas does not dissolve it. There is no reason to put it on banjo bolts because they are not sealing anyways.

I don't put teflon tape on ANY fuel fittings. It will break it down enough to turn it into slime(I've seen it) and you don't want to push teflon bits through your fuel distributor and injector screens. I did assume the OP was referring to tape but he may have been referring to liquid sealant.

[Helirich]

I don't put teflon tape on ANY fuel fittings. It will break it down enough to turn it into slime(I've seen it) and you don't want to push teflon bits through your fuel distributor and injector screens. I did assume the OP was referring to tape but he may have been referring to liquid sealant.

I've used a lot of tape on fuel fittings on helicopters. (Pipe thread) I suppose there's differnt quality tape. I agree, it would suck to get a piece in your fuel injection. The main point is the fuel can leak completely through the threads on a banjo bolt and it still hasn't got out of the line.

[Michael]

I've used a lot of tape on fuel fittings on helicopters. (Pipe thread) I suppose there's differnt quality tape. I agree, it would suck to get a piece in your fuel injection. The main point is the fuel can leak completely through the threads on a banjo bolt and it still hasn't got out of the line.

Jeez I wish you would just shut up. I mentioned banjo bolt because of higher torque tolerances for reusing old seals. You jumped all over that for some reason. Fuck banjo bolts. Put teflon on every single fuel fitting and wrench that shit down with a breaker bar for all I care. Your posts are Bill Robertson and DT all rolled up into one self absorbed asshat.

[DMCMW Dave]

I've used a lot of tape on fuel fittings on helicopters. (Pipe thread) I suppose there's differnt quality tape. I agree, it would suck to get a piece in your fuel injection. The main point is the fuel can leak completely through the threads on a banjo bolt and it still hasn't got out of the line.

The threads are not the seal. The seal is the two copper washers. So sealing the threads won't really do any good.

[Michael]

The threads are not the seal. The seal is the two copper washers. So sealing the threads won't really do any good.

Exactly. With an A/N fitting for example, taping the threads will prevent you from getting a proper seal. Sure It might not leak for the first week or so, after that it's game over.

[Helirich]

The threads are not the seal. The seal is the two copper washers. So sealing the threads won't really do any good.

That was my point. The fuel can leak from one side to the other and not get out of the line. They are not the seal. So why would you use sealant on them?

Michael, you need to have another drink. The only thing we don't agree on here is that fuel will dissolve Teflon tape.

https://www.calpaclab.com/teflon-ptfe-compatibility/

[Helirich]

Exactly. With an A/N fitting for example, taping the threads will prevent you from getting a proper seal. Sure It might not leak for the first week or so, after that it's game over.

You lost me here. An A/N fitting is like a banjo bolt in that the threads aren't the seal. You could put Teflon tape on both A/N fittings and banjo bolts and it has no effect on the seal. In the case of A/N fittings, the threads don't even come in contact with the liquid you are sealing. As I mentioned before pipe threads will benifit from Teflon.

[Michael]

You lost me here. An A/N fitting is like a banjo bolt in that the threads aren't the seal. You could put Teflon tape on both A/N fittings and banjo bolts and it has no effect on the seal. In the case of A/N fittings, the threads don't even come in contact with the liquid you are sealing. As I mentioned before pipe threads will benifit from Teflon.

The tape could prevent the mating flared surface from making full contact. You may have it torqued at the correct flats and the flanges could be barely touching. Like I said, you guys do what you want with your car.

[DrWin]

Does anyone know if the banjo fittings for the fuel lines need any sealant or is the copper washer sufficient?

Like everyone else has already pointed out: The thread is not the seal, the (one use) copper washer is. Also, be very, very concentious with the torque values (everywhere). I made my car inop for 6 weeks by breaking a banjo bolt and ordering the wrong one (as you know). That stuff is just stupid. :)

[David T]

You should not use teflon tape on the fuel system. Pieces (shards) can get loose and plug things up and teflon tape doesn't dissolve. Besides, unless you try to put it on the copper gaskets, it is of no use on the threads of the banjo bolt. If the copper gaskets leak you either have dirt in the joint, a bad or used copper gasket, or something is cracked. The reason you should not reuse a copper gasket is that they get work-hardened when used. They are no longer soft. They will not reseal now unless you use a higher torque and if you try to stop the leak by over-tightening you break the banjo bolt. It is possible to anneal (soften) the copper gaskets by heating and slowly cooling them but it isn't worth it. It makes no sense to take the chance of burning the car up over a copper gasket.

[Midnight Specialist]

Thanks for all the info. I ask because we used tape on the fuel feed line. I have since removed it and cleaned out the line and all the fittings. Now a bigger issue. The 90 degree elbow under the filter has the conical shaped tip stuck in it and the threads are messed up and not allowing the nut to thread on with cross threading. Any ideas how to get that tip out? Ideally, I want to relocate this filter to the engine bay


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[81dmc]

Only type of threads that can get sealing tape or dope are npt. I only use yellow petroleum rated sealing tape for npt in autos. You cannot overdo it either or else pieces can break free. I usually leave a few mm of threads at end of npt without yellow tape for that reason.

As stated previously, white Teflon will disintegrate real quick when exposed to gasoline or diesel. Also no sealing tape should be used in place of the proper washer or flare, period.


Only upgrade/replacement for copper washers are dowty washers imo.