What's the end of a glow plug made of?

[dave.j.robbo]

Cos I've just changed my plugs, and number 3 cylinder had about 3/4 inch missing from the end of it, and looks well burnt out.

A few weeks ago, I heard a bit of clatter from the top end of the engine, wondered what it was, so switched off, checked the oil level, all was well, and I had to get to work, so it was started up (it started fine) and drove to work. No clatter.

Now, recently, possibly since about the same time, it's been a tad troublesome to get going in the mornings. Not surprising, really, if a glow plug was bu**ered.

I did an oil and filter change a couple of weeks ago, to eliminate the thought that it could be a dirty air filter causing the dodgy starting.


Anyway, what damage am I likely to have done?

It still seems to run ok, but there is a bit of smoke on start up. White and black smoke.

Oil and water levels haven't dropped at all.

[BUSHWHACKER]

The only problem I can see is that tiny pieces of the glowplug debris might get stuck under one or both of the valves and hold them open slightly. That maybe the cause of the smoke.
On a positive note, the pieces may be crushed small enough to be blown out of the exhaust anyway.

[dave.j.robbo]

That's what I was thinking...

I've got the new plugs in, but rain's stopped play getting the other bits back on, to check that it starts ok, now there'll be four working glow plugs, and also to check on the amount of smoke...

[dave.j.robbo]

OK, a break in the rain, so back out to the garage I go.

Get it all back together and go for a start.
Success! It starts instantly. No smoke, but the clatter is back.

Quick check of a few things, and off for a short drive (I needed some beer ).

About a mile down the road, the clatter stopped. Now it sounds just as it (mostly) always has done.

So my theory is....

A few weeks ago, a small portion of the glow plug broke off, and rattled aroun the cylinder, until it embedded itself somewhere out of harms(?) way.

Now, by removing the plugs, I reckon I dislodged this portion, or possibly another bit of the plug broke off, and that resulted in the clatter this time round.

It' must have found a nice spot to hide again....

I guess the only way to check what, if any, damage has been done, would be to take the head off.

My thinking is that if it HAS done real damage, then I'll have to take the head off pretty soon, anyway, so I'm gonna leave it and see what happens..

Any thoughts??

[BUSHWHACKER]

Something else I thought of, is the fuel injector. I don't know how much it protrudes into the cylinder head , and will it get damaged by debris. TonyN should have an idea.

[dave.j.robbo]

Something else I thought of, is the fuel injector. I don't know how much it protrudes into the cylinder head , and will it get damaged by debris. TonyN should have an idea.

Fair point.

Surely I'd 'feel' a knackered injector? By it missing, so to speak?

[BUSHWHACKER]

Fair point.

Surely I'd 'feel' a knackered injector? By it missing, so to speak?

Might cause it to dribble rather than spray.

[dave.j.robbo]

Might cause it to dribble rather than spray.

I have that problem after a few beers!!

[BUSHWHACKER]

I have that problem after a few beers!!

[TonyN]

The glow end and injector both live in the pre-cumbustion chamber, I'd expect the end of the glow plug to have been blasted out into the bore pretty quickly, and its unlikely it could make it back in, let along manage to hit the end of the injector.

If its big enough it could get welded to the piston top, and be hitting the head, causing the knocking as the rod bearing takes up the impact of the piston not managing to go all the way up. Had this problem with a washer that had got sucked into the intake and broke up and fused to the piston head. but I doubt the end of the glowplug is big or thick enough to cuase much of a problem.

Its only thin metal shell covering sand and the element wire.

If its not knocking now and running happily, It's probably got rid of the bit or its been flattened enough to not be a problem.

Like you said, the only way to check is take the head off.

[dave.j.robbo]

Thanks for that Tony!!!

Put my mind at ease.






A bit......................