teflon tape ?

swcejk2002

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Aug 20, 2009
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hello gang, I am cleaning up a volvo aq125 engine for my bayliner. I am wondering if teflon tape (or something similiar) should/could be used on threads such as oil pressure fitting (where it screws into engine block)? thanks
 

Don S

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Re: teflon tape ?

Teflon tape has no place on an engine.

It is not the swiss army knife/duct tape of pipe thread sealers.
 

vxtech

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Oct 11, 2008
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Re: teflon tape ?

loctite brand PST -thread sealant in a tube
 

DianneB

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Re: teflon tape ?

Teflon tape is garbage and I wont even allow it in my shop! It may work once in awhile on rolled threads but it is useless on cut threads.

The plumber's white stick is good for most jobs. If you need better, something that seals well and stands up to heat, Master's is the best stuff available but you will probably have to go to a commercial plumbing supply shop to find it.
 

paultjohnson

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Re: teflon tape ?

Teflon tape has no place on an engine.

It is not the swiss army knife/duct tape of pipe thread sealers.

NOWWW you tell me ! :eek: I did use it for a new Oil Pressure Sending unit, on both ends of that little 1 1/2 extender tube actually, Why is it bad, does it melt away? Do you suggest I remove OPSU again and remove the tape? Put it in bare, or with something else ? THX
 

We're Here

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Re: teflon tape ?

Why is it bad, does it melt away? THX

Bob Vila said:
TT50 260SS GRAY STAINLESS STEEL TEFLON-THREAD SEAL TAPE
This tape has nickel pigment color added for use on all stainless steel fittings. Prevents galling, seizing or corrosion. A high density rating, this is the tape for coarse stainless steel threads. Also carries a temperature range of -450F to +550F. Exceeds Mil. Spec. T-27730A. UL Listed

It shouldn't melt, since the top piston ring should only get up to about 320F, and the oil would be much cooler I think. The problem is with the quality, or lack of quality control, in the tape manufacture process. I bought a roll recently to install a new shower faucet, and it came with NO labeling at all. No brand name, no manufacture statement, nothing. Not even a sign over the bin to tell you what it is. We recognize the packaging. I use the stuff on water pipes only.

Note that most Mil Specs were cancelled in the late 80's. Doesn't mean they weren't any good, but the military has been trying to get out of the system engineering standards business and industry has finally started to take up the slack.
 

Brentathon

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Re: teflon tape ?

I use teflon tape quite often, and never have a problem.
You wouldn't (and can't) use it on an aircraft hydraulic system (for example), because of the chance that a piece of tape can contaminate the system, but for a pipe thread fitting on a marine engine, there should be no issues.
It's also good if you want to in effect, control the location of a fitting, as you can change the # of wraps........for example, sealing the brass T ball fitting on a T-stat housing, so the fitting lines up perpendicular to the engine.
I use teflon tape on my block drain plugs for 15 years now......seems fine.
 

JetBote

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Re: teflon tape ?

I've never had a problem with Teflon tape. 1-1/2 wraps usually does the trick. One thing to remember, the oil pressure sending unit, if electric, must be able to ground itself in the threads. 1-1/2 wraps is sufficient to seal, yet break enough on the threads for a ground. Rtv has it's place, but too much can squish between surfaces when mated. When this happens inside the engine, those pieces can break off and find their way blocking the oil pump pickup screen. Teflon should never be used on fuel fittings.
 

Brentathon

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Re: teflon tape ?

Yes, good point on the electrical bonding............I've still used Teflon tape on threads that need electrical contact (i.e. T-stat temp sender); I just make sure I check the continuity with a multi-meter, after tightening it down. I would even check continuity if I used Teflon paste, too. In fact, I go continuity-checking crazy, and buzz-out just about everything...I've been un-pleasantly surprised in the past.

And on another subject; I actually prefer to use Teflon tape (in lieu of paste) on plastic pipe threaded fittings. My theory, is that plastic pipe/fittings flex and move around more, which can continue to squeeze-out paste......I just seem to have more luck with tape in that application.
 

sasto

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Re: teflon tape ?

And on another subject; I actually prefer to use Teflon tape (in lieu of paste) on plastic pipe threaded fittings. My theory, is that plastic pipe/fittings flex and move around more, which can continue to squeeze-out paste......I just seem to have more luck with tape in that application.

Good point....we do the same, no paste on plastic, tape only.
 

HT32BSX115

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Re: teflon tape ?

hello gang, I am cleaning up a volvo aq125 engine for my bayliner. I am wondering if teflon tape (or something similiar) should/could be used on threads such as oil pressure fitting (where it screws into engine block)? thanks

You could probably use it but I have had T-tape leak in a high pressure fitting and if you're not careful it can end up where you don't want it.

A better choice is probably one of the following.


http://www.permatex.com/products/automotive/thread_compounds/a_thread_sealants.htm

http://www.ridgid.com/Tools/Thread-Sealants

http://www.rectorseal.com/chrt.htm
 

Brentathon

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Re: teflon tape ?

And there's really only ONE correct way to apply tape......if you're looking at the end of the threaded pipe (for ex), your wrapping should be clockwise, AND I always start the wrapping toward the middle of the pipe, and end the wraps at the very end of the threaded end. I also use my fingernail to go around a squeeze the tape into the root of the theads....if I want to be extra "nerdy".

Anyone ever use paste on top of tape? I have.....on occasion.......there's no law against it... :p
 

HT32BSX115

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Re: teflon tape ?

Anyone ever use paste on top of tape? I have.....on occasion.......there's no law against it... :p
Yeah. There's no law......But I did find the following at http://en.wikipedia.org/wiki/Thread_seal_tape ......(emphasis and corrections, mine)

Over-use, or mis-application of thread tape may be a hazard. An excess amount of tape can prevent mating threads from fully engaging, therefore reducing the shear point of the threads. The use of teflon tape in addition to a pipe dope compound can also be dangerous, because (there) can become to(o) much between the flanks of the threads. As the tape material is so soft, excess or overhangs may easily break off and form a foreign body contaminant that could jam a valve seat etc.
I don't always believe what I read at Wikipedia since a LOT (not all) of the info may be just someone elses opinion. The above does sound correct to me......and it does reference published papers and magazine articles.


And use too much or both together on a temp or oil pressure sender, and you probably will have "gage" problems because of a loss of electrical "ground" connection...............



Cheers,


Rick
 

Brentathon

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Re: teflon tape ?

I could agree with that....that's why I've used both on occasion.
Yes, it's a good point that you still need an appropriate amount of thread engagement, too much tape could be an issue with that.
And yes, don't use tape if a small strand can cause havoc (i.e. a hydraulic system). But, in the very unlikely event that a tiny strand of tape went into an engine crankcase, I wouldn't expect any detrimental affect. That's why I used teflon tape on my oil pressure sender unit :p

I like Wiki.
 

Bluestream

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Sep 28, 2010
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Re: teflon tape ?

Side note on pipe thread sealants: I was on a large construction site a few years back and watch the pipe fitters install the new sprinkler system inside the building. I asked one guy what they used for pipe dope, and was told " motor oil mixed with Portland cement" I questioned this stuff, and was told they had been using it for over 40 years without issues...
 

ChrisCraftJohnny

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Oct 7, 2009
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Re: teflon tape ?

Now it's time for the machinist to weigh in:

Teflon tape was only invented beacause:

The NPT pipe thread aka National Pipe Taper (Yes that's what NPT stands for.) Is a defective design. NPT is designed to lock and seal on the threads. The taper is 1.47 Deg. from center. This design requires the use of teflon tape, pipe dope or some kind of secondary sealer to ensure a seal every time. You will find that a properly machined NPT will seal satisfactory from time to time. However, you have never purchased an NPT fitting that was made to specs. The reason being, all that crap is made in China now. I have done tests in my shop with N.I.S.T. certified ring and plug gages (thread gages to you guys) and NONE of the China-made fittings gage correctly. However, all the NPT we turn out in my shop are made to these gages. Even so, a sealant of some kind is still used on all NPT fittings. Once again showing it's a flawed design and since a secondary material makes up the seal, gaging is not as critical as in most machine threads. One other point of interest: The metric system of threads had no rival to NPT. There is not a tapered metric pipe thread. And no, BSPT is not metric. Showing that metric engineers did not want to even go near the idea of a tapered thread for sealing.

CCJ
 

Don S

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Re: teflon tape ?

Teflon tape was only invented beacause:

Teflon tape was invented to replace petroleum product types of sealers when used on gasses and liquides that have a serious dislike for oil products. Like liquid oxygen.

Teflon tape when installed wrong can do the following
1. Break aluminum castings (such as fuel filter housing, fuel pumps, etc.
2. Too much Tef Tape and you can insulate the threads from the base metal which will make the sending units non-sending units.
3. To much Tef Tape will cause them to leak.
4. To little or wrong way of wraping will cause leaks.
5. Taping over the end a little will have loose tape going into the sender, or fuel system or whatever you are using it on.

Since about 90% of the poeple I have watched install the stuff, have done it wrong, So, why would anyone recommend it's use.

The ONLY good thing about it, is it doesn't leak in your tool box or get your fingers messy. It sure has nothing to do with sealing a pipe thread joint.

PS: Neither Merc, nor Volvo recommend it. And in a few manuals, it has a warning specifically saying NOT to use it.

So why do you guys like it so much??????????? Doesn't make any sense to me.
 
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