Old style glow plugs

Faber · Nov 25, 2023

When the end of an early type glow plug breaks and disappears into the engine should I try to take steps to retrieve the bits or hope that they will be blown out?

I am concerned about damage, don't want to take the head off, but was thinking of turning the engine over with the new glow plug out.

Probably not enough pressure?

Any ideas or just wait for nothing to go wrong!

Turboman · Nov 25, 2023

Faber said:
When the end of an early type glow plug breaks and disappears into the engine should I try to take steps to retrieve the bits or hope that they will be blown out?

I am concerned about damage, don't want to take the head off, but was thinking of turning the engine over with the new glow plug out.

Probably not enough pressure?

Any ideas or just wait for nothing to go wrong!

Can you explain a bit more clearly?

My reading of this is that the tip has broken off, and you have installed a new glow plug on top of the broken tip?

That isn't a good idea. The broken tip won't "disappear into the engine".
It is most likely still in the bottom of the hole, in which case it will be crushed in by the new plug on top of it, and very difficult to get out now.
The other possibility is that, if a very small piece has broken off the tip, it has been pushed though into the swirl chamber, in which case there is no way you will get it out without taking the head off.

Faber · Nov 25, 2023

Turboman said:
Can you explain a bit more clearly?

My reading of this is that the tip has broken off, and you have installed a new glow plug on top of the broken tip?

That isn't a good idea. The broken tip won't "disappear into the engine".
It is most likely still in the bottom of the hole, in which case it will be crushed in by the new plug on top of it, and very difficult to get out now.
The other possibility is that, if a very small piece has broken off the tip, it has been pushed though into the swirl chamber, in which case there is no way you will get it out without taking the head off.

Thanks.
It looks as if I have made a cock up!

Faber

Turboman · Nov 25, 2023

Faber said:
Thanks.
It looks as if I have made a cock up!

Faber

Yes. You should have posted up when the tip broke off, and we could have told you what to do next.

Have you tried to start it up since the tip broke off?

Faber · Nov 25, 2023

Yes.

Yesterday it was difficult to start but after a 15 sec crank it did and I went for about an hour before returning and checking the glow plugs.

It was then that I found no 4 had a broken end, and replaced it with a new one.

I was thinking of removing it, bringing the piston to tdc and inserting a thin magnetic tipped probe, but I guess that's too late or clutching at straws.

Faber

Turboman · Nov 25, 2023

Faber said:
Yes.

Yesterday it was difficult to start but after a 15 sec crank it did and I went for about an hour before returning and checking the glow plugs.

It was then that I found no 4 had a broken end, and replaced it with a new one.

I was thinking of removing it, bringing the piston to tdc and inserting a thin magnetic tipped probe, but I guess that's too late or clutching at straws.

Faber

Try removing the new plug from the hole where the broken plug was, and putting a rag over the hole, and spinning it over.
A bit of the old plug may shoot out, so keep your eyes and fingers away while you are doing it.
If nothing comes out, replace the new plug, and carry on driving it, if it runs OK the small piece inside the swirl obviously isn't doing much harm. You will probably end up taking the head off sometime anyway, and the swirl chamber cap may well fall out when you do, so you can inspect it then.

Faber · Nov 25, 2023

Turboman said:
Try removing the new plug from the hole where the broken plug was, and putting a rag over the hole, and spinning it over.
A bit of the old plug may shoot out, so keep your eyes and fingers away while you are doing it.
If nothing comes out, replace the new plug, and carry on driving it, if it runs OK the small piece inside the swirl obviously isn't doing much harm. You will probably end up taking the head off sometime anyway, and the swirl chamber cap may well fall out when you do, so you can inspect it then.

Thanks very much for your help.

Faber

Turboman · Nov 25, 2023

Faber said:
Thanks very much for your help.

Faber

No worries.

steve2286w · Nov 25, 2023

Have you got a pic of old one so show what but broke off if it’s just the pigtail would one of them magnetic screwdriver things get it

lynall · Nov 26, 2023

Pig tail type glow plugs?
You might be lucky and the coil bit may still be in the pre combustion chamber.

Turboman · Nov 26, 2023

lynall said:
Pig tail type glow plugs?
You might be lucky and the coil bit may still be in the pre combustion chamber.

Or it could have fallen through the port, into the cylinder, and out the exhaust valve.
Either way, if it is running OK, I doubt it is going to cause a problem now, so carry on as usual might be the best policy.

Faber · Nov 26, 2023

Thanks for all your advice. I tried today to retrieve any bits i) by inserting a thin magnet tipped probe and ii) turning the engine over withe the plug out, and I retrieved nothing.

A later compression test showed that the pot was OK ( at least at the moment ) and it starts well.

It is 43 years old and sometime the head will need to come off, but I am pleased it is still running and grateful for all the different advice I get from the group to enable me to keep it going.

Faber

Old style glow plugs

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