Spark plug getting loose

[missa91]

I have a little problem with my spark plugs. I replaced the whole set about 30K km ago and ever since then the spark plug on the third cylinder is getting loose every 5-8K km. I'm talking about the second cylinder from the transmission. That's the third, right?

I tighten it down firmly, as I do all the other spark plugs, but it always gets loose. I don't know why. And if I tighten it any furhter, I'm afraid the spark plug will break. As I tighten it, it behaves the same as all the other ones.

It stars rattling as if the rockers are without oil, it scares me every time, and always turns out to be the spark plug moving around in the port. It gets so loose, so in the dark you can actually see flames come out of the port.

Is there a recommendation on solving this problem?

[SRDTURBO]

The spark plug thread must be damaged. But you don't need to change the cylinder head, just put an insert or an helicoil:

[missa91]

put an insert or an helicoil

What exactly are these? The image you added wont appear for some reason, so I can't see.
Could you put up links to images so I can understand?

Thank you SRDTURBO !!! It seems everybody else has forgotten about the forum, why is that?

[SRDTURBO]

This is an helicoil:


And this is an insert:


Not everybody else has forgotten about the forum but when you don't do anything on your car you have nothing to post.

[thefunkyboy]

Right Baptiste, we are not on a Renault forum hahaha

But also for some other reasons (a house built for example... tooks huge time!)

For your trouble, could you find a way to find a kind of "fix filet" to maintain the plug at the right place? But to do so, it is mandatory to find the weakest one. (to avoid any permanent stuck!)