glow plug snapped

[NiftyNev]

Probably platinum, Iridium or some exotic metal like that.

Nev

[NiftyNev]

The Glow Plugs are a "Sheathed Coil" construction.

Nev

Diagram from here -

http://www.ngk.de/Sheathed_type_glow_plugs.691.0.html

[NiftyNev]

Here's some info about glow plugs.

http://www.google.com.au/url?sa=t&so...6MAUkA&cad=rja

Nev

[potif]

garage is flat out at the moment so haven't done any more than put it back together with the broken tip still in situe and the centre-drilled body screwed into the hole.

I'm going to run the surf back and fore to work for a few days to see if it will dislodge but after that i'll take the chance on drilling out the tip.

Whatever the tip casing is made from, it is slightly magnetic (304 stainless?)so they may be able to pick it out if it falls in. If the piston is at TDC, then it should stay in the pre-combustion chamber and be easier to get?

[dieselboy]

The Glow Plugs are a "Sheathed Coil" construction.

Nev

Diagram from here -

http://www.ngk.de/Sheathed_type_glow_plugs.691.0.html

Thanks Nev. When I pulled mine out I had a bout a metre of coil trailing back to inside the glow plug hole!
Whats the heater tube made from in this case? I think it isnt metal at all, as it just cracked / snapped and was very dull even on the freshly snapped bit.

[dieselboy]

Glow plugs can and do break of in the head sometimes. Can't really blame the mechanic unless you can prove they were negligent.

I would have tried to epoxy something into the broken tip where it has been partially drilled such a a thin threaded rod, let it set, then sprayed a bit of diesel in the hole and then tried gentle outward pressure while rotating the tip.

Nev

Mercedes are known for this. Their glow plugs are apparently about 2 or 3 times longer than the Surfs, and the soot just cokes them up and grabs them - word from a mechanic.

[NiftyNev]

Whats the heater tube made from in this case? I think it isnt metal at all, as it just cracked / snapped and was very dull even on the freshly snapped bit.

Titanium or Berilium or possibly other metals. Depends on the brand of plug I suppose and the cheaper ones might be made of very dodgy metals. The link I posted has some very interesting info on glow plugs so I suggest everyone take a look before tackling the job of removal. I have yet to break one.

Nev

[dieselboy]

This is how I broke mine:
- used the correct sized socket on a ratchet extension to crack the glow plug loose.
- was slowly winding out the thread
- got about halfway on the thread when we heard the CRACK. I knew immediately something had just broke. There was no resistance on the socket, it was loose and the threads were still being wound out so there was no way possible I had put any sideways force on it.

The one that cracked was the 3rd one I did, the other 3 came out fine.

[potif]

update on snapped glow plug

Garage left tip in to see if it would come out on its own - over a week later and no movement. So yesterday tried to pull it out using an allen key glued in with som plastic metal. Firstly drilled out and blew out any remaining ceramic, leaving a hollow tip about 15mm long. tried to put in the allen key but as I (gently) pushed it in the tip dropped in. So found myself in the same position as dieselboy.
There was no way I was removing my head either, so I crossed everything and turned the key. Firstly, all I could here was the tip rattling around in the pre-combustion chamber. Stopped and started again, rattling stopped then a few revs later heard a rattling sound as it went into the exhaust.
The only damage that appears to have been done is that I have a tappet noise. This may be because the tip stuck in the exhaust valve on the way out and the valve shim slipped out??
No other obvious problems (smoke, power loss etc) and the cold starting is excellent now I have 4 working plugs.
Does anyone know where to get valve shims and what the what the valve clearances should be?

[dieselboy]

EXACTLY what happened to me, down to a T. Exactly!

My biggest mistake is answering the Diesel specialists questions when they asked things like "why is just one valve making noise?" or "why do you think the tappets need shimming?".

If I were you, I would go and buy a feeler gauge. They are cheap. Find the inlet and exhaust valve clearance values and tolerances and check the clearances yourself, before taking it to a garage to have them all done.

When I took mine to a garage, I specified "please measure every valve clearance and adjust IF NECESSARY". I eventually gave in and believed they must be true, which cost me.

I didnt put much pressure on the tip and it went in as well. I drove around for a month, during winter with no glow plug in. I even went along the M25, pedal to the floor to try and get it blown out.

What I am unsure of, is if the tappet noise you have now is either, wear on a shim or the valve has slightly bent? What has possibly happened (how I can picture it) is the tip has been sandwiched between the piston crown and the valve. The cam lobe / shim has worn slightly causing noise when the valve is lifted due to there being more of a gap.

Did you verify that it is in fact ceramic tip?

I also noticed no drop in fuel economy or power. Other than the slight tappet noise, which could only really be heard or noticed when driving. The noise couldnt be heard when the engine was ticking over, and certainly couldnt be heard outside of the car. Any passengers didn't notice even when pointing it out. Obviously we notice (you and I) as we know that there is a different noise than what was before!


I still think you should have got a long screw driver, started the engine and gently tapped the tip to loosten it.
50 / 50 chance that the compression would have blown it out once free! Otherwise you would be in the same situation now.

Can you keep us updated? I'm not sure on how to properly check the valve clearances on this engine though. I've only ever done it on 4 cylinder OHV engines.

Hopefully someone else will comment?

[potif]

I hope it hasn't bent the valve but surely if it had it I would have poor compression and some misfiring. I've had a look for info on valve shims but there is suprisingly little. From what I can gather, the cam pushes down on a cup which pushes down the valve and holds the shim that sets the valve clearance.
Does the shim sit on top of the cup or below it and how thick is it?? If it is quite thin and sits on top my theory about throwing a shim due to lack of pressure holding it in place is fine but if it is fairly thick or sits below the cup then you may be right about the bent valve.

The tip is not ceramic. The metalic casing which encases the ceramic powder and heater elements, goes all the way down to a metal tip. I drilled out all the ceramic until all I could see was a clean metal base.

With regard to working free the tip with the engine running - I wouldn't - if you'd heard the bang as the allen key left the glow plug hole you wouldn't want to be holding it.

tappet is noisy when idling, so sounds worse than yours.

If I can live with the noise (though I probably can't) is this likely to cause further damage. Exhaust valves aren't expensive and, although I really don't want to take the head off, I'll be quite happy to set aside some weekend time to do the job (starting to wish I'd done the plugs myself in the first place).

Any advice appreciated - thanks