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Discussion Starter #1
I'm going to change all the plugs but number four has a Helicoil in it and I'm worried about it failing if we take it out. What's the fail rate of the helicoil?
 

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Why do you have to remove the valve cover gasket to change the plugs? Is the gasket leaking onto the boots and that's why you're replacing it?

If it were installed properly, it would have red loctite on it to ensure it wouldn't come off. Although, I don't know how well that holds up to engine heat.

Also, as you unscrew it, the helicoil tries to open up, but can't because the threads surrounding it are in the way. This should allow the bolt to be removed without removing the helicoil.

Basically, I've never had one come off. If it were to, you could also buy another insert unless it were to break or something. As far as it failing, the helicoil is stronger than your aluminum engine block and is less prone to galling. Just don't over-torque it and you should be fine.
 

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Discussion Starter #3
The number four spark plug hole is shot has helicoil in it worried about it pulling out I am charming all the plugs because it's a lake in there misfiring
 

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Do the work on a cold engine & you should be OK.
 

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Oh, the hole for the plug itself is helicoiled? Yeesh. Good luck!
 

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If it simply pulls out you just screw another in, the threads are already cut for it. Course it helps to have proper tools. Head pulls to cut the thread correctly. If the installer installed it right with a ding in the top thread it won't come out. Use anti-seize on the plug to help out.

More likely that conditions that lead to first plug stripping the hole will lead to another doing it I've found.
 

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Is is an actual Helicoil insert or a Time-sert? If it's a Helicoil, it may well pull out, but you can then install a Time-sert and be done with it--I think that would be a way more robust repair than installing another Helicoil.

The Time-sert involves drilling a bigger hole, so no matter what happens you'll be able to fix it pretty easily. The way the Time-sert locks in place, it's really rare that it'll thread out during a plug change.
 

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Yes you can thread another helicoil into a hole thats had one back out. As for time-sert its not a good idea to make a bigger hole in your head and insert a steel threaded plug into an aluminum head. different growth rates for the metals will cause fautigue and leakage. If you question if the helicoil will come out go to the local auto parts store and get a rethread kit, and just be preped for the worse case. If you dont need it take it back.
 

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Yes you can thread another helicoil into a hole thats had one back out. As for time-sert its not a good idea to make a bigger hole in your head and insert a steel threaded plug into an aluminum head. different growth rates for the metals will cause fautigue and leakage. If you question if the helicoil will come out go to the local auto parts store and get a rethread kit, and just be preped for the worse case. If you dont need it take it back.
While I understand the theory behind the reservations of using a Time-sert due to dissimilar metals, in practice I've never seen a problem--and I've seena few plugs come out of Time-sert hole. The burn pattern is always similar to the other plugs. Besides, if one really cared about it they could use an aluminum Time-sert insert (but I just don't think it's necessary).

OTOH, I've had pretty bad luck w/Helicoil repairs. YMMV and all that, but I'll take the Time-sert repair any day. If one really wanted to do it "correctly", they could use a Lock-n-Stitch insert.
 

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Jack, this kid is uncertain what to do with a helicoil. Handing him a hand drill with a even bigger drill bit and telling him to not mess up cause there's no fix beyond this is not a good thing. This is a very classic case of k.i.s.s. in my honest opinion. And he's prob scratching his head on the whole time-sert and lock-n-stitch brand inserts that you brought up anyhow. Seems as though you might be a fellow machinist?
 

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^^^ good point.

I've used the 'Keen-Sert" brand on Cycle heads before, but saved them for holes so buggered a helicoil wouldn't work. Good option to keep in the box until needed IMHO. If a helicoil fix gets damaged beyond repair, you've still got a potential option.
 

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A helicoil spring coming out is technically not a fail as you can turn around and put it back in again if not damaged coming out. BTDT.
 
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