Sump drain plug

[pennine]

Does anyone know if the plug should be sealed with PTFE tape or not ?

Aiming for a leak free stag engine when it goes back in .

[stustag]

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Hi Pennine

This is a NPT or BSPT thread so is Dry Seal and no need for PTFE tap.

Stuart

[al-stag]

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PTFE tape is completely inert and will help for an easier release next time you undo it

Al

[pennine]

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Thanks for the replies guys, don't suppose it will hurt to put a few turns of tape on in that case.

[Marco Polo]

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My car had a leak around the sump plug that I couldn't cure. It turned out to be the braze around the plug boss had a hairlinecrack. I only found it when I took the sump off to check/clean the oil pump strainer.

regards,

Raoul

[Andrew S]

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Never had to use tape until I bought one of those magnetic sump plugs. I use just a littleand not a drip

[loudnproud]

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If you want to use tape use it, save over straining the brazed on lug which as stated can crack if over tightened.

[15tag]

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The problem of BSP taper threads is that they are really only designed for one off use. Once used the male and female threadsare deformed into each other to form a gas or liquid tight joint. Unfortunately, second time around the threads have lost their initial forms and will not produce a perfect seal again (ask any gas fitter - they normally throw second hand fittings away because they are not worth the heartache of leaking joints). I find over the years of frequent oil changes the plug scews further and further into the sump! A temporary solution is to fit a new plug but thesump taper thread is still worn and distorted. Other cars have the better solution of a plug with a proper machined shoulder and brass washer. Works every time, particularly if a new washer is always used.

I dont see a problem of ptfe tapeor thread sealent if it works. I have just bought a new product from Loctite called "55 pipe sealing cord". Its a thin cord which you wind along the thread. Many gas fitters nowswear by it. I'm going to try it next oil change. If I ever have to take my sump off I will braze in the brass washer type plug

Robert

[stustag]

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Hi Robert

The thread in the sump should be BSPP G series parallel and the sump plug should be BSPT (Tapered). The idea is as you said each time it is used the tapered plug moves a little further into the thread to seal it. If the plug has been made to the correct gauge line taper it will take a long time and many 100's of uses to wear this out completely.

Stuart

[pennine]

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I decided to use tape as already stated the plug is going too far into the sump. I reckon I could screw it in completely and lose it if I didn't use tape.

[15tag]

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Thanks Stuart for a great reply.

You obviously know your threads! We live and learn. I have fitted new plugs in the past but they still screw too far in. I think over the yearsthe overzealous tightening to seal the plug has damaged the female thread. This may be where theory and practice diverge.

Thanks again

Robert

[Giles]

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I always use ptfe on taper thread drain plugs as without they always seem to weep a bit even if they just get a bit damp