Use of PTFE tape

I'm going to fit a (used) oil pressure gauge to my Spitfire. I have all the necessary fittings, but I've read that PTFE tape is advisable on the threads.

I have some tape, but I have no real idea what I'm supposed to do with it. I obviously wrap it round the thread, but how much, and in what direction?

If this used gauge doesn't work and needs to be removed, is there any danger of the tape falling into the sump/blocking the oilways etc?

Many thanks,

David

Reply to
David Balfour
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David,

PTFE tape is one of the best ways of sealing a thread hydraulically, I use it on steam fittings successfully. Put it on your fitting so that the end of the tape you apply is going away from the direction you will turn the fitting. You can never use to much but within reason wind it on the threads until you have at least gone five times around the thread. If you have to remove the fitting most of the PTFE will come off and it is unlikely to get into the oilways unless you poke it in.

Mart> I'm going to fit a (used) oil pressure gauge to my Spitfire. I have

Reply to
Campingstoveman

Depending on how thick and chunky your PTFE tape is, make 4 to 6 or more tight turns of it around the thread, keeping close to the open end of the pipe fitting. Wrap it clockwise, looking into the open end of the pipe, if it's a normal right-hand thread. Then the threading on of the female (hehe) thread won't tend to unspool it.

Remember, you shouldn't, and don't need to, torque it up to two grunts and a fart levels to get a good seal.

Reply to
Dean Dark

Personally I wouldn't use PTFE tape. It will do the job, but IMO it's a plumbers solution to sealing a thread rather than an engineers one. I would advise the use of 'Loctite Hydraulic Sealant' An anaerobic liquid sealant. A small tool supplier should have it in stock. Has the advantage that a union does not have to be tight for it to seal. Something like a guage can be rotated to the correct position, and even if that means backing off, the sealant will still give a pressure resistant seal after a few minutes. I use it regularly at work with hydraulic systems running at far higher pressures than the oil pumps fitted to car engines, so I can assure you it's more than capable of sealing an oil pressure gauge. Plus it's a lot easier to apply than PTFE tape. Although tight when it sets, removal can still be affected with normal tools. Mike.

Reply to
Mike G

I have used PTFE tape, though on domestic hot water fittings rather than on a car, and it works. The fitting advice in this thread is good. I have never tried Mike's hydraulic sealant, but personal experience is usually worth noting.

But - isn't the oil pressure tapping on this block tapered? Every oil pressure switch I have personal experience of has gone into a tapered hole. In which case, you shouldn't need PTFE tape or sealant. Try finger tight then a quarter turn, which should give you an oil-tight seal. If not, tighten SLIGHTLY more.

Jim

Reply to
Jim Warren

The sealant has one draw back over PTFE, expensive.

Mart>> I'm going to fit a (used) oil pressure gauge to my Spitfire. I have

Reply to
Campingstoveman

Campingstoveman ( snipped-for-privacy@btopenworld.com) gurgled happily, sounding much like they were saying :

Exactly. PTFE tape is dirt cheap, available everywhere, does the job, and damn near *everybody* has a roll in their toolbox anyway...

Reply to
Adrian

Compared to PTFE tape you are right, but even a small bottle should last a hobbyist for years, so only a few pence more per union. Enough IMO to justify it's ease of application and the better appearance of the finished joint. Mike.

Reply to
Mike G

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