Glowplug (cross threaded)

dirtydog · Post by **dirtydog** » 05 Oct 2002, 13:32

Hi
Im sure most are aware of the problem of changing the glow plugs on a xantia TD, well the so called most difficult was changed but the 2nd one in from the cam belt end hasnt been changed for a while by the previous owner, the reason being it was cross threaded! I have managed to get it nearly a 3rd of the way out but now there isnt any nut to get hold of it has reduced from a 12mm to a 11mm and now it is only as thick as the rest of the plug.
So now for the request for help. Has any one had this problem before and have they managed to get it out without taking the cylinder head off? and how did they do it with out snapping the plug in two?
Thanks
Regards
DD

alan s · Post by **alan s** » 05 Oct 2002, 16:46

Have you tried the tool they use to remove snapped head bolts? It's hard to describe but it has a small wheel like a couple of small gears that grab it from the sides. The harder you turn, the harder it bites into it.
I assume you have a tap on hand to redo the thread once it's out & if it's gone too far, what are you like at fitting helicoils? If the thread is totally cactus, you may have to take the head off to get a helicoil fitted it you're not tooled up to do it; if this is the case, I'd suggest whipping the head off and letting somebody else have all the aggro<img src=icon_smile_blackeye.gif border=0 align=middle><img src=icon_smile_blackeye.gif border=0 align=middle>
Alan S

Dave Burns · Post by **Dave Burns** » 05 Oct 2002, 17:32

Just because its stiff doesn't necessarily mean its cross threaded, can just as easily be corrosion, especially where steel and aluminium come together.
I'd take the pump off, lightly tap the side of the plug all the way round, soak it with penetrating oil and screw it back in, then out hopefully distributing the oil along the threads, and keep tapping the side of it to loosen it in the threads on the head.
If however you are sure it is crossed, then the only safe solution is to take the head off, not wise to attempt a thread repair in situ as you may not be able to prevent swarf getting in, and if it does after all your hard work, the problems it can cause are far more reaching the initial fault.
Dave

dirtydog · Post by **dirtydog** » 05 Oct 2002, 20:55

Thanks for the assistance.
I will have another go before the cold weather gets here.
Regards
DD

sooty · Post by **sooty** » 06 Oct 2002, 00:18

I had a similar problem some time ago with a 309 with a 1.9d.
It was rust in the cyl.head in the threads.
As dave say's, use some penetrating oil or the next best thing is a drop of Diesel. Leave it for a few hours and then try to screw it back in a bit also rocking it back forth (screw in then back out) and slowly working your way in.
I don't like the idea of tapping the sides, as these are basically a tube and if you are heavy handed, hitting these too many times, they will snap off, likewise if they are that tight to twist them off when trying to screw or unscrew.
The tool Alans was refering to is a 'stud extractor', but you will have to remove the pump to use one.
If you are successful in removing it or them, refit them with Copper grease on the threads.
Good luck
sooty
Edited by - sooty on 05 Oct 2002 19:21:07

davethewheel · Post by **davethewheel** » 06 Oct 2002, 04:01

like dave suggested probably seized rather than cross threaded, had the same prob on a zxtd plenty of freeing oil and working the plug did the job good luck dave

NiSk · Post by **NiSk** » 07 Oct 2002, 13:38

Just a couple of words of advice, having had similar problems with the glow plugs on my XM TD12 (2,1l). Use Plus Gas penetrating oil - it really is the best. And use aluminium paste instead of copper paste - there's enough trouble with electrolitic dissimilarities with just two different metal types - don't make it worse by introducing a third!
//NiSk