Glow Plug Replacement 1.9 TDI AVF

Dear DIY enthusiasts,

Since I'm currently replacing the timing belt and the glow plugs in my car probably haven't been changed ever, I'm wondering if I should do it now. However, I'm still traumatized by my previous Passat (1.9 TDI engine): two stripped glow plug threads, requiring a complete overhaul, including removing the cylinder head, etc. (Some of you might remember the story). Do these problems actually occur in PD engines?

"Definitely, the current glow plugs are no longer in good condition and don't look particularly new either. However, since I don't drive much anymore and the winters here are mild, the engine usually starts quite well. Is it worth taking the risk? What happens if the threads fail and the glow plug can't be unscrewed (below the point of breakage)? Can you simply leave the glow plug in, or will it eventually shoot out? Would it be helpful to warm up the engine and apply WD-40 and freezing spray to the glow plug just before unscrewing it? Is it possible to repair the threads without removing the cylinder head (according to YouTube, it seems possible)?"

Are the spark plugs broken, yes or no? If not, then I would leave them where they are.

Warm up the engine beforehand and carefully remove the spark plugs. Let the engine cool down and reinstall the spark plugs. There is a special glow plug paste available from Beru. I used ceramic paste for the threads.

Very important:
Don't try to pull the candles out in one piece. Instead, move them "back and forth" repeatedly. In my opinion, this significantly reduces the risk of them breaking.

Rüdi wrote:

Are the glow plugs broken, yes or no? If no, then I would leave them where they are.

Hello Ruedi,

"However, it takes a few seconds for all the burners to ignite properly when the temperature is below freezing. Since this rarely happens in my area, I actually don't bother with it. I was just hoping that this problem wouldn't occur with the PD engines (e.g., due to larger igniters, etc.)."

Quote:

Warm up the engine beforehand and carefully remove the spark plugs

.
Why preheat? Aluminum has a higher coefficient of thermal expansion than steel, meaning the tensile stress on the mandrel is higher when it's warm.
hg
Herbert.

I thought it was the other way around. You're right. Then it's obviously counterproductive.

"In my 3BG PD engine, the glow plugs also came out very easily, even after high mileage. I wouldn't hesitate to remove them (if they are worn out)."
haithamina

Actually, it's more about how the spark plug seals and how the threads move against each other as they heat up.
My previous thought doesn't apply to a screw with a head that sits on top, because the GK (presumably a gasket) doesn't seal there, but rather at the bottom with the cone. Therefore, that argument doesn't fit.
hg
Herbert.

First, check each glow plug individually for continuity. If there is continuity, there's a 90% chance they are intact. Conversely, if there is no continuity, the glow plug is 100% defective.