Is this the remnants of a helicoil repair?

[strang]

Double checked my valve clearances today and one of the exhaust valve cover studs just started turning freely. When I tried to back the dome nut off to have a look the stud came out as well as this spiral of aluminium (?).
Is this the remnants of a helicoil repair or is this just the way they go when they strip?
I'm an idiot so if someone could walk me through how to repair this that would be great.

 

[strang]

is this what i need?
http://www.ebay.co.uk/itm/Thread-Re...139?pt=LH_DefaultDomain_3&hash=item4154f4bb63

 

[5twins]

Helicoils are stainless, what you got are the threads that used to be in the head. Yes, now it's stripped and will require a helicoil repair and yes, a kit like in your link is what you'll need.

 

[GreasyC]

Those seem to be the most strip prone bolts on my bike too. Somewhere here I read that a few of them are open to the head on the end? Anyone know if that's true? If it is you really shouldn't be doing helicoils on them without taking the head off because making some loose metal shavings is an unavoidable part of the process.

 

[strang]

I think part of the culprit with my bolt stripping is these crappy warped bent washers that were in place when I got the bike. They are a hassle to get off by themselves and you can pull them off with the cover but then you are stresses the bolt into the head join. I took all of them off today and just left the little locking washers on - the are pretty old and flat now but still do their job and come easily.

Just so no-one gets on a stress about the "bolts being open to the head" issue that had me worried overnight - they don't. End of myth.

that is just camera shine in the back and the hole is quite shallow, maybe 20mm deep, and has metal at the back.

 

[cooperxs650]

Those seem to be the most strip prone bolts on my bike too. Somewhere here I read that a few of them are open to the head on the end? Anyone know if that's true? If it is you really shouldn't be doing helicoils on them without taking the head off because making some loose metal shavings is an unavoidable part of the process.

It looks to me as if the acorn nuts were over torqued.

As far as chips getting into the head, a helicoil also has a tang that cannot be allowed to contaminate any moving components. I think some of the old timers will tell you to use a lot of grease on a drill bit and tap when you prepare the hole as a way of catching the chips so they wouldn't fall into someplace you don't want them. You can also retrieve the tang by attaching a small piece of fishing line to it before you install the helicoil. I did that on a Vstar 650 and it worked fine.

 

[5twins]

Originally, those acorn nuts had just one plain thick flat washer under them, no lock washer. You may need a special bottoming tap to install a Helicoil in a blind hole like that.

 

[Dorzok]

use these
http://www.timesert.com/index.html

 

[jd750ace]

WOW! Gorilla twisted your nutz! Looks like a feeble attempt to arrest an exhaust leak in the past. More people should get manuals, and learn about stuff like torque wrenches and exhaust gaskets!
I feel your pain bro. That's one of the risks with an older bike, and some newer ones!

 

[kvanderploeg]

I had one do that too. Used a Helicoil just fine. I would recommend using a drill bit stop collar. Just help you from getting too over zealous and drilling too deep.

Kent

 

[650Skull]

WOW! Gorilla twisted your nutz! Looks like a feeble attempt to arrest an exhaust leak in the past. More people should get manuals, and learn about stuff like torque wrenches and exhaust gaskets!
I feel your pain bro. That's one of the risks with an older bike, and some newer ones!

Tappet covers

 

[strang]

Here was my solution (?) today.
what I started with:

don't want any shavings in my valves do I:

hi-tech depth measuring tool:

first tool from a helicoil set, drill bit with tape depth guide, use spray grease as lube:

tap from helicoil kit, use tap fluid as well:

pushing in the helicoil insert:

original bolt back in:

looks good:

Had a bit of an issue though. Basically for anyone else that needs to do this - it is very easy if you get a helicoil kit and go real slow, using tap fluid and some other lubricant with the drilling. But and this is a big But - make sure you get a secondary tap and use this after the first tap that comes with the kit. The second tap has thread cutting all the way to the tip whereas the starter tap has a smooth taper to get it started. What this means with a blind tap (tapping where you are not going all the way thru the material) is that you can't cut thread all the way to the back of the hole with just the first tap. Of course I only realised this too late.

In practise today this meant that my helicoil insert wouldn't go all the way in. I then cut the bit that was jutting off and thought it would be ok. I then screwed in the original bolt which seemed to get very tight. I think this is because the helicoil gets tapered towards the back as there isn't any thread cut at the back. I wanted to pull it out and use a secondary tap but it was stuck very firm and so I just carefull screwed it in a couple of ml and it was done.

However now I'm stressed that over time it may cause a crack as the bolt is compressing against the steel helicoil in a slightly underdone hole in an aluminium head. eek. seems ok but I'm trying to care for this old girl, not cause other issues. thoughts?

 

[5twins]

Like I said, you needed what's called a bottoming tap. They're made special to tap to the bottom of a blind hole. They have full cutting threads pretty much their whole length. What's a "secondary" tap? Never heard of one. Go to the store and ask for one but just be prepared to get laughed at.

 

[weekendrider]

You should have read post #7?

 

[strang]

apologies - second tap.
from wikipedia.
"Intermediate tap, second tap,[2] or plug tap[4]
The tap illustrated in the middle of the image has tapered cutting edges, which assist in aligning and starting the tap into an untapped hole. The number of tapered threads typically ranges from 3 to 5.[3] Plug taps are the most commonly used type of tap.[citation needed] In the US, they are commonly known as plug taps, whereas in Australia and Britain they are commonly known as second taps."

from this thread I read and focused on post 3:
"Helicoils are stainless, what you got are the threads that used to be in the head. Yes, now it's stripped and will require a helicoil repair and yes, a kit like in your link is what you'll need."
I bought the kit as it was confirmed by people more experienced than me as what I needed and used it today.

post 7 contains the word "may" so I didn't focus on this as the difinitive solution:
"Originally, those acorn nuts had just one plain thick flat washer under them, no lock washer. You may need a special bottoming tap to install a Helicoil in a blind hole like that."
I have done my best today. I am where I am.
sheesh

 

[5twins]

You did fine. I've never seen a Helicoil kit that comes with the bottoming tap. They sell that extra so they can make more money on you. They also closely guard the tap sizes so you can't just buy inserts and tap your own holes with a normal tap you have on hand.

I said you "may" need the bottoming tap because if a blind hole is deep enough, the normal helicoil tap will make enough threads and the insert will go in.