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Stripped Plug thread
wicket - 15/1/08 at 11:34 PM

I have friend with a 'K' series that has stripped a plug thread. He considering buying from Namrick a repair kit that consists of a tap, a fitting tool & helicoils. Anybody had experience doing this, any tips/problems to pass on. Any help much appreciated.

Jon Ison - 15/1/08 at 11:53 PM

Never fitted "helicoils" my self but have the odd one done here and there, I remember a gearbox mount on an Audi and a stripped spark plug thread on an old 2 stroke, both repairs lasted the lifetime of the car/bike without any problems.

Is it worth buying the kit as apposed to just taking the head to someone that has one ?

thunderace - 15/1/08 at 11:58 PM

UMMM take off the head as you will fill it with alloy from the tap
it will work .
done it on high comp 2 stroke.

russbost - 16/1/08 at 12:01 AM

The ones we used to use weren't actually a helicoil but a complete thread which was cold rolled into the drilled out plughole, we used to blast the cylinder out with a blowgun b4 refitting the plug - fitted dozens never had any probs other than occaisionally the thread would come back out with the plug when next removed - quickly resolved with some loctite on the thread when refitted

britishtrident - 16/1/08 at 07:32 AM

Big problem is that on the K16 like most other twin camshaft 16 valve engines the plugs are deeply recesssed.

Here is the alternative type to helicoils.
http://www.agriemach.com/product_info.php?cPath=34&products_id=722

All goes to underline the leason that if you suspect a plug isn't going in straight take the plug out and run a thread chaser down the threads.

PS the plug thread length on the K is long reach 3/4" long.



[Edited on 16/1/08 by britishtrident]

David Jenkins - 16/1/08 at 08:48 AM

And also start the plug by hand - if it won't go most of the way with just your fingers, there's something wrong!

r1_pete - 16/1/08 at 12:49 PM

quote:
Originally posted by David Jenkins
And also start the plug by hand - if it won't go most of the way with just your fingers, there's something wrong!


and for deep seated plugs use a bit of rubber hose which is a light push fit on the insulator, itl'll slip before shagging the threads.

Coose - 16/1/08 at 01:04 PM

And don't forget a dab of oil on the threads....

As mentioned, a well-fitted helicoil insert should last the lifetime of the head. In fact, you do quite often see helicoils fitted as standard on automotive threads into alloy (motorbikes are a good example). Even if the fastener size is up to the job, the thread may not be so by fitting a helicoil you're actually increasing the threaded area.