300tdi stuck glow plug

[strewth]

Gents, Hi.

Been having trouble starting disco in the cold weather. Put some new glow plugs in. Three swapped no worries. Fourth will turn but won't come out and won't retighten either.

It will wobble in the hole but won't move in or out.

Thoughts?

Thread gone on the head?

Thread gone on the plug?

But then why won't it pull out?

Any suggestions on what I've managed to do and how I might get the stupid thing to work again would be much appreciated.

Thanks

[BogMonster]

I think you have to bite the bullet and get it sorted properly. This means try to get it out and if it won't come out, don't start the engine or even turn it over, get the head off, and get all of it out which may require a milling machine to drill down precisely through the middle of the plug (just missing the threads) and then clean up the threads. It isn't a Black & Decker job, you can't do it with the head on the engine (risk of swarf and bits in the bore) and the job needs proper gear but it can be done. I've seen a TDV6 that needed all six done like this, every one snapped off. Good old boy with a milling machine and a steady hand had it sorted in a day or so, good as new.

Nice present for all those happy D3 owners in a few years because they are all going to do it, a very weak/thin steel bodied plug that is a very very tight fit in an alloy head

If the threads in your head are fked you may need to get it Helicoiled which will save the head.

If you can't hear any tss tss tss when the engine is running you might get away with using it like that but equally the nose might drop off the plug into the cylinder when the engine is running and trust me that is a horrible noise which will make you jump a yard in the air and probably write off the engine (bore chewed up, alloy head with dents in). You don't want that, heard it once on a Td5 and I was standing next to it when it dropped, cheap non gen glow plug only in there for about 4 months and the end fell off, bang bang bang new engine needed in about 10 seconds.

[JimAttrill]

I broke a 'county' plug the same way a few years ago. Although mine is fixed in the head. So now I have only 3 glow plugs that work. My engine has 290k kms on it and I will eventually get the plug out when the engine is reconditioned (soon). As it still starts fine and runs fine I will have to wait. Maybe sometime next year. So don't worry about having only 3 glow plugs. After all, the TD5 has four!

[nicedayforit]

This might be of help if worst comes to worst and you need to get the glowplug out.

http://www.peachparts.com/Wikka/OM606BrokenGlowPlug

[tonka12]

i had the same on a merc 300d and it was the very rear heater plug.it snaped just under the nut.so nothing left to turn.i welded a nut on it several times and it came out after two hours swearing and bloody knuckels hope this is some help russ

[JimAttrill]

Reminds me of when I was in Germany in the early '70s. A friend had bought an old Merc 190 and brought it to show us. I said "It's not too noisy for a diesel" and he said "It's a petrol!" A nut had fallen off the air cleaner and was rattling up and down in the bore