I recently had the engine on my VW Golf TDI replaced with a reconditioned engine.

After having start up problems for a while, I asked an independent mechanic to have a look. He found that one of the glow plugs was the wrong type - it was longer than the others.

I've included an image of it, showing some damage.

enter image description here

Since replacing with the correct glow plug, the car won't start. I'm worried that using the wrong glow plug for so long may have caused damage to the piston.

Does anyone have experience with the damage that can be caused by using a glow plug that is too long?

Many thanks.

  • 1
    Have you checked the fuses and relays to ensure they are still working? I'm wondering if the mechanic somehow disrupted the power circuit going to the glow plugs. Commented Mar 13, 2016 at 17:31
  • So it has been working with the wrong plug fine and when it was replaced the car no longer starts? Commented Mar 14, 2016 at 9:21
  • @IhavenoideawhatI'mdoing, I'd have a good look over the electrics in case the mechanic disconnected something and forgot to reconnect it, yes.
    – Chris H
    Commented Mar 14, 2016 at 15:53
  • What kind of damage is that anyways, doesn't look like it was hit by a piston. What is that thing on it? Commented Mar 14, 2016 at 17:11

1 Answer 1


If there was any significant contact between the glow plug and the piston, I think you'd know it right away (horrible noise followed by horrible quiet). I'd double-check the glow plug wiring and electrically check the fuses -- fuses can fail without blowing, and the only way to know for sure is to check for continuity. I'd also suggest you double-check your fuel pump relay, or check your fuel pressure if you can. Can you hook up the glow plug while it's removed and verify that it does glow (or at least heat up)?


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