Citroen XM Forum

Update - my original plug has been so badly damaged that I completely misunderstood how it locked into place, resulting in my first few posts in this thread being quite wrong. See my post of April 21 (2024) for correct information - end update

I have an SII hatch, with the ES9J4 V6 engine. I have broken the bottom off the radiator top filling/bleeding plug so that it no longer locks into place (photo below). This plug fits into the N/S (passenger side) end of the top tank.

The parts diagram doesn't list it as a separate part, so I don't have a part number.
However in the following diagram it is #5.
Any suggestions? Googling only brings up radiator drain plugs, which sadly are not interchangeable. I have tried glueing it in place with silicon, but that only seems to work for a while...

Either wait and see if one turns up, or contact a radiator remanufacturer and see if they have them, or a solution, or drill the thread out and install a shanked bolt and O ring after cutting a suitable thread.
If you have the threaded part, so you know what thread it is, you could have one made in either plastic, or metal.

That's part of the problem - there's no thread. I should have taken a photo of the hole in the radiator, but the bit missing off the bottom of the plug is basically the head of a 'T'.

The bottom of the hole looks something like this:
so obviously the head of the Tee locks under those lugs.

No idea where the broken off bit is - floating around in the cooling system?

I'm sure what you see down the hole is the broken plug, still screwed into the threads.

The plug is thinned to allow water to pass through before it is full unscrewed, however this creates a weak point...as you have found.

See if you can unscrew the rest of the plug, measure the thread diameter and pitch and make a suitable replacement.

Thanks Dieselman for taking an interest and offering suggestions - your daily efforts to help anyone and everyone with whatever problems they come up with are deeply appreciated. It would be a very quiet forum without you!

This is not the bottom drain plug - it is on top of the radiator, on the LH (passenger side) end of the top tank. It is #5 in the diagram above, and the text (which I should have also copied) describes it as a "bleed screw". The radiator drain plug is #14.

I got it out successfully once or twice, so I saw what is looks like - which is why I describe it as an inverted Tee. It was plugged into the radiator, sealing nicely and minding it's own business, when I bumped it, snapping it off at the thin neck. If it was a bleed screw I'd certainly have no trouble finding something that would screw in, but this #$@^&* thing seems to be unique!!!

I have checked the parts diagrams for Xantias, 406s and 605s that had this engine in the late '90s - Xantia had moulding that looked like it could have been designed for this plug, but was left blanked off. 406 & 605 might have the plug - parts diagrams are not particularly clear.

Here is an attempt to improve the picture of the socket - the black tabs are the lugs that the Tee locks under, the green is coolant just below .

I understand it now, the fitting is a bayonet fitting.

You could have a plug made specifically in either plastic, or metal, but it would be simpler to drill the barbs out and cut a thread in, and install a bolt and O ring.

I am still in need of this part, but now have a much better idea of what it should look like. I have tried using various sealants to "glue" the plug into place, without any success. It is really irritating not to be able to use my Xm because of something so trivial!!!

I have found that the same plug is also used in Pug 406s, even with the later ES9J4S engine. There is also some evidence that 2.0 litre engined Peugeots (& presumably Citroens) from around the year 2000 may also have this plug.

Here is a photo of an undamaged plug:
As can be seen, the section below the o-ring has lugs, which lock into the hole in the radiator. The "feet" (missing on my damaged plug) are only there to keep the plug from falling out when unscrewed.

The expensive option would be to replace the whole radiator. It appears Nissens can still supply a replacement (listed by Spareto as available, but with a 28 day lead time), although by the time I pay freight it will be over $400 (Australian).

I am told that the Nissens radiator has an equivalent bleed plug, but that it is bigger, so there is no point in me contacting them in search of just the plug for my radiator.

Can you not drill and tap for a tapered, or straight, plug to be screwed in?