cross-threaded spark plug, do I need to remove the head?

victor65

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Hi everyone, brand new to the forum..great info.
My situation is: I've got a '94 c220. About 100k and 75k miles ago, I re-tapped two seperate spark plug holes and placed threaded inserts. This worked great until I recently changed the plugs, and one of the inserts came out with the plug. When I screwed it onto the new plug and screwed it back in, I cross threaded the insert into an already re-tapped hole.
My questions: Is there another kit to re-tap another larger diameter insert that will have the same inside diameter for the plug? Am I just going to have to pull the head? If I pull the head, with 235k miles on the car, what other things should I renew while the head is off?
I appreciate anyones time on this.
 

mercmadjim

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In my area there is a guy who will come to your house and fit a helicoil, as long as he can get his device in square you can leave the head on.
My mate had his done, it cost £15, that was about 2 weeks ago.
 

kebo57

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Hi everyone, brand new to the forum..great info.
My situation is: I've got a '94 c220. About 100k and 75k miles ago, I re-tapped two seperate spark plug holes and placed threaded inserts. This worked great until I recently changed the plugs, and one of the inserts came out with the plug. When I screwed it onto the new plug and screwed it back in, I cross threaded the insert into an already re-tapped hole.
My questions: Is there another kit to re-tap another larger diameter insert that will have the same inside diameter for the plug? Am I just going to have to pull the head? If I pull the head, with 235k miles on the car, what other things should I renew while the head is off?
I appreciate anyones time on this.
Hi you must have the kit that you used for the two threaded inserts might be some sizes on the taps so we ascertain the size of the insert tap and the thread diameter of the spark plug.
Helicoil & thread inserts are different thing, different tap diameters. but an oversize insert could be made but not a oversize helicoil

Kevin
 

Irish CClass

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An old fixit

You could try cutting a cross, two cuts at right angles to each other, down through the threads of an old spark plug having removed both electrodes first. Pack the centre of the plug with grease and start screwing it in S-L-O-W-L-Y, maybe one or one-and-a-half turns at a time and then remove it going a little farther each time.

The plug should recut the thread and the slots will guide the swarf into the centre of the plug and the grease will hold it there. That's why it's important to remove the plug every few turns or so to clean out the swarf.

This worked many years ago on a Renault 12 with an aluminium cylinder head.
 

roadhog

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When I screwed it onto the new plug and screwed it back in, I cross threaded the insert into an already re-tapped hole.

A bit late in the day but you should have put the insert in the head then fitted the plug as inserts expand when you fit a bolt or plug. It might still be worth a try although without the correct tool or even a new insert you may struggle.

You could try cutting a cross, two cuts at right angles to each other, down through the threads of an old spark plug having removed both electrodes first. Pack the centre of the plug with grease and start screwing it in S-L-O-W-L-Y, maybe one or one-and-a-half turns at a time and then remove it going a little farther each time.

The plug should recut the thread and the slots will guide the swarf into the centre of the plug and the grease will hold it there. That's why it's important to remove the plug every few turns or so to clean out the swarf.

This worked many years ago on a Renault 12 with an aluminium cylinder head.

This method may work on an aluminium head but not once you've got a helicoil (steel?) in there. I'd be very worried about the swarf as well.
 

LYNALL

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Just get the correct tap for the insert run it down the threads and stick in a new insert.



Lynall
 


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