Radiator bleed screw.

There are invariably things about our cars that irritate, for me a number of those are displays of ineptitude usually, but not exclusively by previous owners. The radiator filler screw was one such thing, it looked like it had been set upon firstly by false teeth, then the sort of Stiltson usually reserved for dump trucks.
The part number is PYP100500 & on eBay, they are £9-25 which is simply too much for something which is plastic & has the propensity to cross thread. However for a more reasonable £4-30 you can have a M12 x 1.25mm Steel Drain Plug Blanking with Recessed Rubber Sealing Washer, again from eBay supplied by mcconnectors (213). It looks nicer also. QED

I've never tried it myself but someone once told me that an old spark plug will work... :-o

Should do; same thread. My preference is for the plastic fitting as it is mugh easier to drill out if it gets stuck. Radiators tend to be fragile.

Valid point, mind it’s stainless so shouldn’t corrode, a little graphite grease on the threads usually makes for trouble free removal at a later date.

Looked to me like zinc plated which I would fit but NEVER would I fit a stainless screw into an aluminium radiator. Electrolytic corrosion would be guaranteed within months. Graphite grease is another no-no. Homebuilt aeroplanes have their aluminium bits marked in felt marker and never pencil. Graphite penetrates the pores of aluminium and cannot be removed. Once it gets damp, a corrosion cell is formed and you don't want that in your wing spar! Why do you think that the obscenely parsimonious Rover company use an expensive piece of plastic instead of a cheap steel screw? Better to turn one up in brass if you want something different.

Very interesting prior to this post I would have opted for a SS replacement, now I'm torn between 24K gold and plastic although gold is also easy to drill out.

Fourteen carat would of course be better as the zinc content will neutralise the copper and it is nowhere near as soft so less likely to strip. A cheaper alternative would be Argentium which would be fine from the corrosion perspective. It is ductile, doesn't tarnish and will withstand most chemical attack. I use it to make watch cases for people with allergies to conventional silver.

There’s a lot of stuff there to digest & you’re never to old to learn. The screw is stainless according to my magnet & I’ve used molyslip ever since I could get the lid off my dads tub. We’re a Land Rover family & anything would be used to mark out the Birmabright ali when doing repairs, never considering the possibility of a wing falling off, I suspect that the chassis would have decomposed long before something as spectacular as that took place.
Replacing the old plastic plug has nothing to do with aesthetics & all to do with finding a replacement that seemed to represent better value & I wished to pass that nugget on, it now transpires to be poor advise & to all those who have rushed out to “upgrade “ I apologise.
I could indeed turn up a brass equivalent, however my lathe is a venerable Myford & is calibrated in imperial units, thus thread cutting a 12mm x 1.25mm thread isn’t as straightforward as rattling up a Whitworth thread.
Thank you for the advice, I shall ponder. M

Land Rover family and the moniker Airportable does that mean you have a lightweight LR, if so I'm jealous.

You're jealous.

It's just peeping out over the top of the f, it's not been on the road for a while. I could handle it when I was younger but it's generally too heavy for me now, my legs are shot & I can't hop up into the driver's seat. Getting out is easy, I simply cascade out into a snotty heap on the pavement.
It wasn't unusual for there to be a couple of lightweights, a couple of forward control 101s & S1,S2 & S3s sat outside on a Saturday. We weren't always popular then, my neighbours much prefer the shouty exhaust on the f over the two101s V8s etc. M

If you can’t manage the Landies any more you’d better send them to me to look after……….. yeah I know, my ambitions exceed my capabilities….