Tread sealant for diesel?

Ian_Edwards

Ian_Edwards

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Hi, I'm making up some 3/8th inch BSP pipe fittings for the diesel fuel supply, engine, generator and heater. Speaking to the local mechanic he advised not to use PTFE tape, he'd had problems with bits of tape coming adrift and causing problems.
What should I use, bearing in mind that the fitting are mixture of SS and brass, and parallel and tapered threads?
Cheers Ian
 
I bought a tube of Hylomar Blue when I refitted my diesel fuel float but I tried it first without the sealant and the nitrile gasket sealed without any problem.

The Hylomar is still unopened but a small tube of that will do the trick on threads.

Richard
 
Very bad practice to use sealant on fuel systems, I did an apprenticeship with shipping companies, wewe not permjtted to use any sealant on fuel systems. Fuel has a habit carrying detritus through the system and blocking the fine tolerances found in the system. Do not do it.
 
third engines said:
Very bad practice to use sealant on fuel systems, I did an apprenticeship with shipping companies, wewe not permjtted to use any sealant on fuel systems. Fuel has a habit carrying detritus through the system and blocking the fine tolerances found in the system. Do not do it.
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That's impossible to achieve I'm afraid. A tapered thread on a diesel connection will leak if there is no sealant or tape on it ..... absolutely guaranteed!

Sealant is usually preferred to tape for the very reasons that you suggest.

Richard
 
RichardS said:
That's impossible to achieve I'm afraid. A tapered thread on a diesel connection will leak if there is no sealant or tape on it ..... absolutely guaranteed!

Sealant is usually preferred to tape for the very reasons that you suggest.

Richard
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Hah! Is that why I've always had the very smallest of drips from the tapered 'plug' going into my fine fuel filter? I've chickened out of tightening it any more. result. So Hypalon Blue or the rediculously (sp?) expensive Loctite 572?

Donald
 
RichardS said:
That's impossible to achieve I'm afraid. A tapered thread on a diesel connection will leak if there is no sealant or tape on it ..... absolutely guaranteed!

Sealant is usually preferred to tape for the very reasons that you suggest.

Richard
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Im with you Richard. Texaco forbade teflon eventually after it was discovered that bits floated around systems causing blockages. My preference is blue Hylomar. Just a smidgeon.
Used on gas turbines and aero engines etc.
Beats red Stag which was all we had when I was an apprentice!
Stu
 
I use JetLube V-2 Plus on these types of threaded connection. Useful stuff because you can also use it with gas and potable water. Another good thing is that years down the line when you come to undo the connection it is easy to clean off.
It should be avaliable in your local diy store or plumbers merchant.
Use on the male threaded part leaving the first thread clean.
 
Aja said:
Hah! Is that why I've always had the very smallest of drips from the tapered 'plug' going into my fine fuel filter? I've chickened out of tightening it any more. result. So Hypalon Blue or the rediculously (sp?) expensive Loctite 572?

Donald
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Put that spanner down Donald ...... you're on a hiding to nothing I'm afraid. :)

A touch of Hylomar Blue round the thread, but not on the very end thread, will stop it.

Richard
 
I always use compression couplings for fuel - for pipework. Copper olives - dry. Anything else is either banjo type or - if hose to copper - a proper hosetail - not a stub of pipe.

I thought the proper fitting for fuel were flared type - as in brake pipes ?
 
Just how often do you see this sealant bodge on your new out of the box engine? Ssystems should be correstly engineered, taper to taper, banjo or couplings with soft metal or fibre washers, nuts and nipples in preferance to olives. A well engineered systdm should not need any help to seal. Sealant however has its place as a thin smear on face to face joints, VP sumps to name but 1 or as a mid atlantic get you home when a replacement is not available.
 
third engines said:
Just how often do you see this sealant bodge on your new out of the box engine? Ssystems should be correstly engineered, taper to taper, banjo or couplings with soft metal or fibre washers, nuts and nipples in preferance to olives. A well engineered systdm should not need any help to seal. Sealant however has its place as a thin smear on face to face joints, VP sumps to name but 1 or as a mid atlantic get you home when a replacement is not available.
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Absolutely right. My fuel lines have no sealant on any of the fittings and there are no leaks.
 
third engines said:
Just how often do you see this sealant bodge on your new out of the box engine? Ssystems should be correstly engineered, taper to taper, banjo or couplings with soft metal or fibre washers, nuts and nipples in preferance to olives. A well engineered systdm should not need any help to seal. Sealant however has its place as a thin smear on face to face joints, VP sumps to name but 1 or as a mid atlantic get you home when a replacement is not available.
Click to expand...

I'm sorry Third Engines, but this is getting painful. You have clearly never had to use a tapered fitting so you really should not be posting on this thread. :ambivalence:

And it's no good saying "I wouldn't use a tapered fitting" as some fuel/gas/water components are supplied by the manufacturer with BSP, or similar, tapered pipe fittings so you don't have a choice. If you don't use tape or sealant on a tapered fitting then it will never seal with fuel or gas.

Richard
 
I was introduced to liquid PTFE by my son, who used it on refrigeration and air conditioning systems on superyachts. He told me that once he began to use it he never suffered a leak, whether on refrigerant or water joints. I have found it to be superb, even sealing worn O-rings on my Jabsco pumps. It has none of the problems of PTFE tape, so no risk of strands being driven downstream (although I'm not sure I would use it on fuel pipe joints downstream of the secondary filter)

Screwfix sell it, although my tube of it came from Spain.
 
parsifal said:
Absolutely right. My fuel lineshave no sealant on any of the fittings and there are no leaks.
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I'm just unlucky I guess. My tapered connection has leaked from new. Supplier advised me just to nip it up a bit

Donald
 
skipper_stu said:
Im with you Richard. Texaco forbade teflon eventually after it was discovered that bits floated around systems causing blockages. My preference is blue Hylomar. Just a smidgeon.
Used on gas turbines and aero engines etc.
Beats red Stag which was all we had when I was an apprentice!
Stu
Click to expand...

Stag paste was great, as long as you didn't want to undo the joint again, without the use of a hacksaw! :encouragement:
 
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