I should have known better !

[LittleShip]

I posted a question on P.B.O.

"I have used PTFE to seal the threads on my fuel lines and now find that this may not be suitable for the job.
What should be used to seal threads on diesel fuel lines??"

Wasteful lot over on PBO. Got told to use olives,olives indeed Ha! sod that everybody knows that olives go in the gin.
Seriously though, what can I use to seal the threads if PTFE isn't suitable.
Come on Mobo show the overall brigade up and give me the answer /forums/images/graemlins/smile.gif

Tom

 

[powerskipper]

ask Col, he will know or boatone.

 

[LittleShip]

Julie.................for a moment I thought you had gone techie on us?? /forums/images/graemlins/grin.gif

Tom

 

[Col]

I use face seals, and here's the contraversial bit, ... PTFE tape as well (just as a back up) The face seals do the actual sealing though. As others have said, olives on compression joints.

 

[Sammo]

If you have a male thread to go into matching female thread PTFE is the way.

Say a flexible fuel pipe to a fitting.

cheers

 

[Freebee]

loctite make a super thread sealant Ithinks its 561 or summat Ive proved it on diesel and kerosene and petrol. liquid when it goes on, exclude the air and it goes solid but only use for permanent jointing.

 

[jumbo]

If itsa good tight fit tom it should not need a thing ,i will check it out for you at the marina when the sun shines!

 

[studgies]

The seal on fuel pipes comes from the olive being compressed and needs no sealant or thread compound added.

If there is a leak it is more likely that either the pipe has weakened and the olive spins on it or the pipe or olive itself has a crack somewhere, these can be difficult to spot.

On diesel engines you need a good seal for 2 reasons, firstly the obvious one so it doesn't leak fuel, but if the poor seal is before the priming pump you'll have difficult starting, smoking etc due to air being drawn into the fuel line.

I hope this helps.

 

[cliff]

[ QUOTE ]
I posted a question on P.B.O.

"I have used PTFE to seal the threads on my fuel lines and now find that this may not be suitable for the job.
What should be used to seal threads on diesel fuel lines??"

Wasteful lot over on PBO. Got told to use olives,olives indeed Ha! sod that everybody knows that olives go in the gin.
Seriously though, what can I use to seal the threads if PTFE isn't suitable.
Come on Mobo show the overall brigade up and give me the answer /forums/images/graemlins/smile.gif

Tom

[/ QUOTE ]If you had been more specific as to what you are trying to seal perhaps you would have received an appropriate answer. If you are talking about banjo unions then annealed copper washers are used, if you are talking of compression joints then olives are used, if you are talking of male fittings being screwed into female receptacles such as filter/separators then taper threads do not need any seal but straight threaded fittings will normally have a shoulder on them for an annealed copper washer. Other types still going around require a lead seal like a cup or lead foil. The main reason for NOT using PTFE tape is little bits can (and frequently do) break off and wind up blocking the injectors as can happen with hylomar and loctite type products if applied too liberally to unions downstream of the filters.

Finally if you want to use PTFE tape for sealing Diesel lines I suggest you use "red 3 or yellow 3" type tapes which are specifically manufactured for the oil & gas industry and are resistant to diesel fuel amongst other things unlike the plumbers PTFE tape which can degrade in contact with organic solvents (diesel)

If you have any further questions please contact your local HGV repair shop and ask what they use for sealing diesel lines on trucks.
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