Diesel Drip Best Sealant Please.

[Guest]

very briefly, slight drip on the tank diesel tap today and it stinks, as well as messing up the bilges. There is a barrel nipple screwed into the (female) tap and that is where the leak is. It is currently (not) sealed with PTFE (pipe tape for engineers) but I find this is crap for diesel. Also as once told it was bad practice to use it. So brethren of the forum, is there a sealant in a tube that would do a better job? Hylomar, Red Hermetite etc?

I hate boats.

Many thanks

[RLWP]

Just nip it up. It doesn't need glues and potions

 

Richard

[andyb116]

Locktight 572, designed for LPG in its liquid form, works brilliantly with diesel and unleaded under high pressure, bit pricey though.

[ditchcrawler]

Is it on the tank side of the valve or the down stream side?

[Tony Brooks]

or from the spindle - is it a taper plug type tap or O ring type?

[Silebyman]

Try Rectorseal Tru Blu - you can get it in little tubes so you don't need to buy big tins of the stuff.

 

I used it recently when I tapped a fitting into my diesel tank. It's resistant to diesel, and suitable for vibration prone environments.

 

It's available from amazon, and probably other places too - can't remember where I got mine from.

 

https://www.amazon.co.uk/Other-Tru-Blu-50g/dp/B00P2FY8XS/ref=sr_1_2?ie=UTF8&qid=1469183594&sr=8-2&keywords=tru-blu

[Guest]

Thanks so far. The leak is after the valve which has female thread with a (I believe) taper fitting that receives the copper pipe and olive. Tried nipping up but no improvement. It appears to be a taper thread into the valve with ptfe around it. Not sure now if leaking at that interface or olive. Am going to dismantle the thing tomorrow when near chandlers.

Edited July 22, 2016 by Guest

[Bill]

Thanks so far. The leak is after the valve which has female thread with a (I believe) taper fitting that receives the copper pipe and olive. Tried nipping up but no improvement. It appears to be a taper thread into the valve with ptfe around it. Not sure now if leaking at that interface or olive. Am going to dismantle the thing tomorrow when near chandlers.

 

Turn off valve, unscrew taper nut and pull out of valve, if the olive looks OK (not deformed), check how much pipe is protruding from olive (if its too long the olive will not seat properly). As it has been previously tightened the olive will probably be solid on the pipe and hard to move, the joint may have been over tightened in the past and the pipe crushed quite a bit. in most cases replacing the olive (and the pipe if necessary) will cure the leak. No need for PTFE or any other potions. Do check inside the valve where the pipe fits for burrs or damage (unlikely). Couple of quid for pipe and a few olives (if you replace the pipe you will need one for the other end as well) should see you leak free and a happy bunny.

[Guest]

Many thanks should be able to get olives tomorrow so will have a go then

[Drayke]

Thanks so far. The leak is after the valve which has female thread with a (I believe) taper fitting that receives the copper pipe and olive. Tried nipping up but no improvement. It appears to be a taper thread into the valve with ptfe around it. Not sure now if leaking at that interface or olive. Am going to dismantle the thing tomorrow when near chandlers.

You forgot to put Swindlers between near & chandlers.

[Guest]

What a bloody job that turned out to be! A job that should have taken an hour took most of the afternoon. The original fitting had been tightened up by Guy the Gorilla who had cross threaded the thing and used about a yard of shitty PTFE tape to try and seal it. this had degareded and a lot had found its way into the valve; just hope not too much has got in the fuel line; time will tell. The only susprising thing is that it didn't pull air in, and never leaked for 12 years (until now.) Undoing the thing was awkward but i managed by sort of lying on my side. The new 1/4 BSP x 5/16 fitting was a bit too long to fit in the female valve so I had to saw it down a little. Luckily I was able to reroute the pipe slightly and just saw a bit off including the knackered olive. I used Blue HYlomar to seal the tapered thread into the valve. Seems OK now but will check for a while.

One question; is Gas Safe PTFE tape better for diesel, or does this degrade too?

Thanks to everyone who posted.

Forgot to say the Chandlers at Norbury Junction where extremely helpful and had everything I needed.

Edited July 24, 2016 by Guest

[Bill]

I don't think PTFE tape or the Gas version (which is just thicker) is actually degraded by diesel. PTFE goes stringy because the actual threads chew it to bits as the joint is tightened giving the impression that is is rotting.

[Guest]

I don't think PTFE tape or the Gas version (which is just thicker) is actually degraded by diesel. PTFE goes stringy because the actual threads chew it to bits as the joint is tightened giving the impression that is is rotting.

Thanks, wasn't sure TBH. It did look like it had somehow degraded, but as you point out may be just an illusion. Certainly the other connectors into the tank seem OK and they are sealed with PTFE, so will keep an eye on them.

I learned today that Blue hylomar is available in a thinner version for this very job.

[rjasmith]

Just to add another alternative which I've found works well for me - Rocol "Oil Seal" - this is specially formulated to seal up threads and other fittings wherever anything oily is involved.

 

I've used it on all my diesel day tank pipework and got everything leak tight at the first go which is not always achieved with my plumbing techniques!

 

Richard

[Guest]

Just to add another alternative which I've found works well for me - Rocol "Oil Seal" - this is specially formulated to seal up threads and other fittings wherever anything oily is involved.

 

I've used it on all my diesel day tank pipework and got everything leak tight at the first go which is not always achieved with my plumbing techniques!

 

Richard

Mental note made, my plumbing is not the best technique either! That said,I can do a better job than whoever fitted this plumbing connection to my engine