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PTFE tape in fuel lines?
blakep82 - 6/9/11 at 08:48 PM

is it quite ok to use PTFE tape on any screw in unions on fuel pump, fuel pressure regulator etc?
can't decide if i think it will break down with petrol or not? any better sealing options?

adithorp - 6/9/11 at 09:26 PM

That really odd. Just mins ago I had a phone call from a mate who's just out of Gibratar and has a leaking fuel line. He wanted to know if PTFE is OK with diesel as the line into his fuel filter is leaking and the wind's the wrong way to rely on sail. I said it probably was but doubt it'd be OK if it was petrol.

adrian

ps. if anybody knows differently please let me know so I can warn him before he looses signal on his phone.

daviep - 6/9/11 at 09:46 PM

PTFE sealant tape is suitable for petrol and diesel (and pretty much every other liquid).

Davie

blakep82 - 6/9/11 at 09:53 PM

hmm, been doing some googling myself, you get fuel lines made of PTFE, so i'm thinking ptfe tape can't be much different.
davie, is that just standard ptfe plumbers tape then? i don't think there's any special types, but i saw something on american forum saying something about a yellow one?

stevegough - 6/9/11 at 09:56 PM

quote:
Originally posted by adithorp
That really odd. Just mins ago I had a phone call from a mate who's just out of Gibratar and has a leaking fuel line. He wanted to know if PTFE is OK with diesel as the line into his fuel filter is leaking and the wind's the wrong way to rely on sail. I said it probably was but doubt it'd be OK if it was petrol.

adrian

ps. if anybody knows differently please let me know so I can warn him before he looses signal on his phone.



If the wind is as bad in the Bay of Biscay as it is here, he'll need more than PTFE tape to get home!!!

Dingz - 6/9/11 at 09:57 PM

PTFE is inert to most things, the worst thing that could happen is small bits of tape breaking off but a filter will stop it getting too far.

Mr C - 6/9/11 at 10:21 PM

I've been advised to use PTFE on my flexible brake lines into the front calipers, I'm not keen on the idea at all, anyone have any views either way on this?

daviep - 6/9/11 at 10:34 PM

quote:
Originally posted by Mr C
I've been advised to use PTFE on my flexible brake lines into the front calipers, I'm not keen on the idea at all, anyone have any views either way on this?


If they have a tapered fitting such as NPT or BSPT then PTFE tape would be an appropriate sealant, if however it is a parrallel thread then PTFE tape would not be appropriate. Simples.

In the case of a tapered thread there are also liquid sealants which will do the job just as well and may also give a degree of locking which may be desireable if the hose is twisted due to steering action.

Davie

snapper - 7/9/11 at 06:08 AM

If you put flexi lines direct into a front caliper you need a lock nut.
Most production cars have a small length of fixed pipe that is then secured to the hub or bracket, the flexi goes into that with a spring clip and lock nut.
Just putting the flexi straight into the caliper with a bit of thread lock is not a clever idea.
I cut down an appropriate nut used it as a lock nut and used a drop of thread lock on that.

adithorp - 7/9/11 at 07:14 AM

quote:
Originally posted by snapper
If you put flexi lines direct into a front caliper you need a lock nut.
Most production cars have a small length of fixed pipe that is then secured to the hub or bracket, the flexi goes into that with a spring clip and lock nut.
Just putting the flexi straight into the caliper with a bit of thread lock is not a clever idea.
I cut down an appropriate nut used it as a lock nut and used a drop of thread lock on that.


I'm sorry but that is just not true. Not since the 70's anyway. The vast majority of production cars have flexi pipes direct into the brake calipers. In fact, I can't think of any that don't currently do it that way. None of them have locknuts at the caliper.

Having said that mine have a short ridgid pipe, so that the flexi runs to a point nearer the steering pivot line, so that the flexi isn't subject to as much change in length while turning. It does have to have suitable brakets to stop it vibrating.

PTFE shouldn't really be use on normal brake pipes as the seal is made by the taper on the end and not by the thread. If it doesn't seal there are other issues with the fitting/caliper/tube-flare. The only exception would be taper threads like those found on Wilwood calipers but even there other special thread sealing solutions might be better.

Steve, don't worry he's very experienced off-shore sailer and is well aware of the risk to his clients craft. He'll make what progress he can and put into port whenever needed.

britishtrident - 7/9/11 at 08:56 AM

Only problem is you can't be 100% sure a flake of tape will enter the fuel system and block an injector. So if i was using it after the filter I would blow the fuel lines through after assembly

Personally I would prefer to use Loctite "Loc n Seal".

britishtrident - 7/9/11 at 09:15 AM

I hate to see home builds with the wrong type of hose end screwed straight into the calliper and sealed with tape/Loctite/brute force
For many years most UK manufacturers just ran the flex straight to the calliper or wheel cylinder with a copper washer as seal, This arrangement never gave any problems, however the accepted practice gradually changed as over the last 25 years or so as manufacturers switched to floating callipers. These days nearly ever car has some sort of locking device on the calliper end of the hose (often just clipping the hose to the strut to stop it twisting) .
A proper locking device is particularly important where a banjo fitting is employed.