Strange glow plug death: Regelwendel glows

Hi!

It happens from time to time, but it's been happening more frequently lately (with two cases on the same AFN).
I wanted to ask you all what you think might be the cause, or whether you've experienced this before.

"In some Bosch Duraterm glow plugs, the heating element remains cold, while the control element becomes hot/glowing after a longer period and increased current draw. This means that when testing the glow plugs while they are still installed, they may appear to be working correctly, but the engine still fails to start in extremely cold temperatures (or..." Engines with higher mileage may have difficulty starting, especially in temperatures below -10°C. They may also experience occasional misfires in individual cylinders after a cold start and emit bluish smoke.

It appears that a housing closure is forming at the transition between the control coil and the heating coil. However, this only seems to happen with Bosch Duraterm GSK spark plugs; I've never noticed anything like it with Beru or Champion spark plugs, for example (although those are not as commonly used).
Does anyone know the explanation for this?


Greetings.
vwSchrauber: VW car enthusiasts/mechanics/tinkerers.

Carefully disassemble using the thin flexible disc and inspect the parts.

Yes, I'll do that as soon as I have time. Now that it's getting cold, and all the vehicles are acting up, I hardly have time to put the tools down .

I believe that with the development goal of always increasing the temperature to 1000 degrees, the amount of material used is being reduced, which makes everything more delicate and prone to failure.
Possibly only for your specific GK type or brand?
I usually sell Beruka candles, and I haven't had any returns yet.

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I think that with the development goal of always reaching 1000 degrees, the amount of material used is being reduced, which makes everything more delicate and fragile. Possibly only for your specific GK type or brand?

That's another point: so far, this only applies to Bosch products, and they maintain the full material thickness (except for the slight taper) almost all the way to the tip. Champion's comparison models, on the other hand, are noticeably different about 3mm before the tip, and do not have this problem.
Beru should, as far as I know, have a very similar design to Bosch.

Okay, I've spiced it up a bit now.

It seems to be a rather hard material, because the cutting disc is gradually disappearing, while the CNC machine is happily running .

It appears that the sealant material within the glow plug has "sintered" with the heating element, and coincidentally, it's located precisely where the injector spray passes. Since this issue only occurred in 2 out of the total number of machines, I will check the spray pattern of the nozzles and see if the alignment of the spray is unfavorable for those specific machines.

Super recognized.
It works better with the thin stainless steel flex discs.
Can you rotate the nozzle by 10 degrees?

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It works better with the thin stainless steel flex discs.

I had a 1mm steel washer... If I had known how hard that stuff was, I would have approached it completely differently, but once you've already started using the flex, laziness prevents you from re-orienting it.

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Can you rotate the nozzle by 10 * degrees?

What do you mean by that? It can only carry as much as the support brackets allow – it's an AFN (VP37) model.
With a PD engine, I would have adjusted the relevant PDE values further away from the critical range, but it's not that simple with a VP37 TDI .

Yes, it's a steel disc, but not a stainless steel disc.
If it's not rotatable, then remove it and press it out, if the effort isn't too much for you.

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If it's not rotatable, then remove it and press it out, if the effort isn't too much for you.

I'll do that as soon as everything is "winterized." However, the (series-)nozzles have only been in for 35,000 km .
I set those back then to 230 bar in the first stage, making sure all the gauges showed the exact same reading.

vwSchrauber wrote:

The (series) nozzles, however, have only been installed for 35,000 km . I set them back then to 230 bar in the first stage, making sure that the needle width was exactly the same for all of them.

Does that mean that larger (tuning nozzles) were installed before?

Or "mass-produced nozzles" from China?

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Does that mean that previously, larger (tuning nozzles) were installed?

No, just old nozzles.

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Or "mass-produced nozzles" from China?

I thought Bosch manufactured those products in India?

It appears that the sealant material in the glow plug has been 'sintered' with the heating element.

According to my professor (who used to be a development engineer at Bosch), the coils are inserted into the casing along with fine-grained magnesium oxide, and then the casing is compressed around the circumference until nothing moves inside.

However, I don't know if that's still state-of-the-art; the candles he was handing out still had a thread and nut around the contact to screw them in.