AdamQ Posted May 10, 2012 Share Posted May 10, 2012 I'm planning to have a crack at helicoiling the spark plug thread in the head of a BMW Mini Cooper tomorrow after the plug blew out and stripped most of the thread. I've read up on how to go about this - use plenty of grease when tapping to catch the swarf and stop it falling into the cylinder and what have you, and I've got the two stage tap which means no drilling thankfully. The only question I haven't been able to find an answer to is this: what stops the helicoil insert from simply being wound down into the cylinder when the plug is screwed back in? I can only think that one has to be careful not to tap the entire hole to the larger, outer, helicoil thread in order to give that something to bottom out on - is this correct? Any advice much appreciated. Adam Link to comment Share on other sites More sharing options...
Neil66 Posted May 10, 2012 Share Posted May 10, 2012 Take it to a machine shop and have it done right - if you absolutely must do it yourself - use a timesert, not a helicol... 😬 Link to comment Share on other sites More sharing options...
Eugene Posted May 10, 2012 Share Posted May 10, 2012 I did an old TR7 of mine years back (I know, I know - a TR7 😳). Had no probs, but do use a timesert, not a heicoil! Good luck - but not that difficult really Link to comment Share on other sites More sharing options...
mic Posted May 10, 2012 Share Posted May 10, 2012 Find someone with a Timesert kit. The insert can't wind down. Link to comment Share on other sites More sharing options...
AdamQ Posted May 10, 2012 Author Share Posted May 10, 2012 Thank you all for your wise words! Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted May 10, 2012 Share Posted May 10, 2012 Speak to Richard Young at Automotive Engineering in Uckfield - he saved me when No. 1 son had this happen on a spark plug thread. Link to comment Share on other sites More sharing options...
Bricol Posted May 10, 2012 Share Posted May 10, 2012 Nowt wrong with helicoils -if fitted correctly. Rarely have them come out at work - we fit them in alloy components that will be continually dismantled/assembled in machine maintenance/set-up to save wear and tear on the alloy. Friction is what keep's 'em in - the action of winding them in with the tool keeps them tightly wound and so free running. Wind in flush, stop winding, break the tang, or however your kits instructs, and use. We do use other inserts in higher force applications though. Bri Link to comment Share on other sites More sharing options...
LesG Posted May 10, 2012 Share Posted May 10, 2012 Don't be put off using the helicoil kits; Vickers in Barrow-in-Furness use them all the time in the construction of our nuclear subs! As Bricol, says, take your time, do as instructed, et voila! Link to comment Share on other sites More sharing options...
Roger Ford Posted May 10, 2012 Share Posted May 10, 2012 stop winding, break the tang Which goes where? Link to comment Share on other sites More sharing options...
captain chaos Posted May 11, 2012 Share Posted May 11, 2012 Thats just what I was thinking roger... Link to comment Share on other sites More sharing options...
AdamQ Posted May 11, 2012 Author Share Posted May 11, 2012 From what I've read, in this case you break the tag off by pulling with needle-nosed pliers as opposed to pushing it out with a punch or something similar ... Link to comment Share on other sites More sharing options...
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