[bob d]

what is the best thread sealant for the fittings when installing a mechanical oil pressure gauge?

[steve25]

You should not need anything since it’s pipe thread, but good old Teflon tape like plumbers use works as long as you know which way to wind it and use no more then 2 wraps..

Either way just don’t make the sender too tight in the oil filter adapter since that has been known to crack them in that area.

[Trevor78]

And you still have to make sure it can ground properly or it won't work.

[bob d]

I'm talking mechanical oil pressure gauge not electrical. sorry about that.

[Cliff R]

This is what I use here when working with NPT fittings, whether it be for the house or automotive. Been using it at least 30 years now and tossed out all the teflon tape once I discovered it. I just used some the other day to install a new hot water plate exchanger for the boiler. Never had a single leak since switching to it.......:

https://www.autozone.com/sealants-gl...E&gclsrc=aw.ds

I'd add here that a few years ago my brother who does HVAC, in floor heating, etc was complaining about the poor quality of NPT pipe, fittings, etc and was having leaks on occassion and having to re-thread fittings and pipe due to poor sealing qualities. He was using teflon tape and not always able to get things to seal up which is very frustrating on a big job when you are all done and do your pressure test. I bought him a tub and he stopped using teflon tape and hasn't had any issues since the switch.....

[mgarblik]

Originally Posted by Cliff R

This is what I use here when working with NPT fittings, whether it be for the house or automotive. Been using it at least 30 years now and tossed out all the teflon tape once I discovered it. I just used some the other day to install a new hot water plate exchanger for the boiler. Never had a single leak since switching to it.......:

https://www.autozone.com/sealants-gl...E&gclsrc=aw.ds

I'd add here that a few years ago my brother who does HVAC, in floor heating, etc was complaining about the poor quality of NPT pipe, fittings, etc and was having leaks on occassion and having to re-thread fittings and pipe due to poor sealing qualities. He was using teflon tape and not always able to get things to seal up which is very frustrating on a big job when you are all done and do your pressure test. I bought him a tub and he stopped using teflon tape and hasn't had any issues since the switch.....

That same sealant Cliff mentioned also works great on head bolts that pass into the water jackets like all 34 of them on a small block Chevy. Their genius engineers thought that was a good idea.

[chuckies76ta]

Another sealer that works awesome on hydraulic lines and brake lines. I just did some brake fittings in Wilwood calipers and worked great. 1/8-27 NPT fittings. Very expensive though.

https://www.permatex.com/products/th...=936&radius=10

[Schurkey]

Originally Posted by chuckies76ta

Another sealer that works awesome on hydraulic lines and brake lines. I just did some brake fittings in Wilwood calipers and worked great. 1/8-27 NPT fittings. Very expensive though.

https://www.permatex.com/products/th...=936&radius=10

^^^ I have not tried this stuff, but I am curious.

Thread tape has NO place on an engine. None. Yes, it can "work". It can seal pipe threads. Problem is, it's a shredding mess when you eventually remove whatever it was you sealed with it, and then the little pieces and strings of the stuff get inside the oiling, fuel, or coolant system and cause problems. Used on certain home applications--the natural gas piping of a furnace or water heater, that stay in place and aren't disassembled for decades, maybe.

The "Teflon" stuff recommended by Cliff can be acceptable. Clearly, he likes it. I tend to trust Cliff, he's smarter than the average bear. But my actual experience over thirty years is different from his on this. I have used it to seal steel-shim head gaskets, and that's about the only use I have for it any more.

Sealing tapered pipe thread, or sealing straight threads like headbolts, I leave to Permatex/Loctite "PST" (Pipe Sealer with Teflon/PTFE) anaerobic sealers which "cure/harden" in the absence of air and the presence of "active" metal such as iron, steel, brass (not aluminum.) If used on aluminum or other non-"active" metals, it'd be best to spray the aluminum with Loctite/Permatex "activator" before assembly.

There are several products in this group, the easiest to source is "592". I've told the story before, about the company I worked for switching from an anaerobic sealer to the brush-top "Teflon" sealer, and then confiscating all the brush-top tubs about a week later because leakage problems went out-of-sight. The anaerobic stuff is all I'll use for thread sealing.

https://www.amazon.com/dp/B0002KKTH2...v_ov_lig_dp_it

[gtokid1968]

592 Is great stuff!
I have been using it for 27 years for oil ,fuel, vacuum, (Very DEEP vacuum) argon and nitrogen.
I always trust what Cliff says and know of other peolpe that use what he sugest with no problem.

[i82much]

i love this stuff, threadlocker and a sealant together:

https://www.permatex.com/products/th...ompound-35-ml/

[GtoFM]

I agree, Teflon tape should NOT be used. The reasons, as mentioned, it shreds and who wants that in their engine. I spent 36 yrs. in the HVAC/Plbg industry and sealant mfgs. showed us how we were incorrectly applying sealants. No sealant on the first 2 threads, read the label. Sealants, especially Teflon, are also an excellent lubricant which can lead to over tightening. Malleable pipe and fittings will stretch where aluminum, oil filter adapter (see above), and cast iron will crack!
Ck. ftg. mfgs. for recommendations especially those with a torque spec.

[Dragncar]

I think its being over complicated. Its a little 1/8" pipe oil pressure line.
Its pipe thread and you need some sealant, never dry. Even if its steel to brass, if you want it to leak, put it together dry.
When I was young at a job the owners son told me its not required with steel to brass on a hydraulic pipe fitting. So I argued with him and he kinda wanted to fire me. But it leaked, I knew better. My dad was a heavy equipment mechanic with a shop truck and I watched him a lot.
The OP can use pretty much whatever thread sealant he wants. Even good ole Pematex #2 will work fine.
I would not use teflon tape anywhere in a vehicle. Unless you want a little piece of that tape getting stuck in your check-ball.
Any of the Permatex thread sealant will work fine, its low pressure anyway. Laco Slic- Tight is good stuff. Rectorseal will work but its a little thin.
I like Gasolia thread sealant, its nice and thick.
About the only time I use the tape is when I have a issue at work where the threads are less than ideal and I need something to take up space.

[Skip Fix]

I use the Permatex #14 great stuff!

[hurryinhoosier62]

Hylomar is also a good thread sealer

[bob d]

Thanks for the replys. seems like I have a lot of good choices to pick from.

[Elarson]

Count me among those who won't use teflon tape. I've had 100% success with Loctite 567 pipe sealant over a lot of years. The stuff Cliff recommended is probably equally as good.

I've used it on steel, aluminum, brass, PVC, stainless steel. Used it on hot and cold water, gasoline, oil, nitromethane, methanol and compressed air. It dries but is still pliable and comes apart with no problem.

I've bought it at Grainger and Amazon.

Eric

[Dragncar]

My first Holley rebuild I used teflon tape on the fuel pump. A piece ended up stuck in a needle and seat. Never again, I want something that if a tiny bit gets past the threads it has a chance of mixing-making it through the system and not just getting stuck somewhere and causing a problem.
Again, pretty much anything will work for what the OP is doing. Most car guys have some Permatex in their toolbox. #1, #2 and Aviation and all of them say they work on thread fittings.
One sad thing though, Amazon shows CHINA as the country of origin for Permatex.
What is the world coming to when Permatex is made over there, shame.

[lust4speed]

Only gripe I have with the Permatex thread sealant is it gets really thick after a few months. Anyone know of a thinning solution? I tried mineral spirits and the result was a total failure with globules of white sealant floating in the mineral spirits. The thicker sealant still works for larger household pipes but trying to spread it on a 1/8" pipe plug gets interesting.

A surprising winner for thread sealant is Gasgacinch. Was at the track with just that to use and it worked great.

[Dragncar]

You thin the white Permatex with acetone. But all the brush top cans, every one, Permatex, Slic Tight, Rectorseal, Gasolia get thick with age.
Gasgacinch is a contact cement and they just dry up with age. Seen many a can of CAT Cement, the green stuff dried solid.
The stuff that comes in the little tubes seem to last, they do not get exposed to much air.
Tonight at the mill I had a 2" pipe cap that gave me trouble. Its on a spray booth for treating wood with a anti mold liquid as it goes through a planer. You have to clean this pipe once a month and the threads on the 2" pipe/cap get jacked up. It leaked with just teflon tape. Tried tightening it to the max, leaked.
Rectorseal with teflon tape on top of it fixed the leak.

[chuckies76ta]

Originally Posted by Elarson

Count me among those who won't use teflon tape. I've had 100% success with Loctite 567 pipe sealant over a lot of years. The stuff Cliff recommended is probably equally as good.

I've used it on steel, aluminum, brass, PVC, stainless steel. Used it on hot and cold water, gasoline, oil, nitromethane, methanol and compressed air. It dries but is still pliable and comes apart with no problem.

I've bought it at Grainger and Amazon.

Eric

Same here. The 567 works on all pipe threads as small as 1/8" and smaller if needed. I've been using it for years with great results. The nice thing about 567 is it's a smooth paste, goes on threads very easily.