Hello, I am getting ready to install Fuel Pressure, EGT, and a Boost Gauges in my truck. My question is about thread sealant on the treads of fittings and senders. I am going to install a tapped banjo bolt on top of my filter housing and a needle valve will be installed in that. I don't see a lot of recommendations for Teflon tape and I am not sure if I can get a good seal without adding something to prevent leaking. Does anyone have any suggestions? For the EGT gauge I was planning on using an anti-seize on the treads of the sensor. How about for the boost sensor? Is anything recommended for that connection? Thanks for your help.

Teflon tape

The purpose of this white, non-sticking tape is to serve as a lubricant when threaded parts of a piping system are being assembled. The inherent slipperiness of the material makes assembly easier.

Strictly speaking, Teflon tape is not a thread sealant. The tape may have the effect of clogging the thread path, but it does not actually adhere to surfaces as a true sealant should. During installation, the tape must be carefully wrapped in the direction of the threads or it unravels and tears.

Advantages

Teflon tape can be applied quickly with no mess. It supplies sufficient lubrication to enable pipe system components to be easily assembled without damage to threads. The product is easy to carry and store, and has an indefinite shelf life.

Disadvantages

Teflon tape does not adhere to thread flanks, and does not provide a secure seal. Because the tape is thin and fragile, it is prone to tearing when pipes are being assembled and tightened. Bits of torn tape can migrate into a fluid system, clogging valves, screens, and filters. Teflon tape may be dislodged during pipe adjustments, allowing leak paths to form.

Recommended uses

Widely used in plumbing, this material is adequate for assembling standard water pipes and fittings. Teflon tape offers no resistance to vibration and should be avoided in high-pressure systems.

Bottom line, you shouldn't need it with the NPT fittings, as they're tapered to start with, and are designed to seal upon tightening.

Brass on brass and brass on steel I dont use anything. Steel on steel I would rather use a sealant. Advance Auto has some that is diesel compatible. Not all thread sealants are compatible with fuels.

I never use thread sealants or teflon tape on any fittings. Just way too risky of getting a small particle into the Injection pump that might cause damage or into a injector and plug it up.All my fitting are assembled with self-sealing brass fittings that do not require any sealant or tapes.

The fittings are tapered so they don't need sealant. I never installed any whenever I do any gauges. The only one to use is anti-seize if you plan on removing the egt probe, but I have also removed them before with no problems.

Great, thanks for all the responses.

Permatex makes a good sealant. I use them on my fittings for the Fuel pressure gauge. Since I was having fuel leaks and was not allowing an accurate pressure reading.

It works like a charm. Says not to use with diesel, but it has not dissolved on me yet and its been over a year.

Just for an update....I installed my guages and like some suggested I did not use any sealant on my fuel pressure sensor. I bought a tapped banjo bolt from Geno's and installed my needle valvle into that and the sender screwed into the valvle. I torqued it all to about 18 ft lbs and no leaks, it seems to be holding fine. Thanks for advice.

I use thread sealant on everything, even on the fuel lines. Follow directions, apply carefully starting with the third thread. Never a leak.