Re-coil or Helicoil needed

[FlyingDutchMan]

I seem to have a problem. One of the threads has been stripped from a head bolt recess. I've tried several auto shops/engineering places and helicoil/re-coil suppliers and none of them have an M7 helicoil in stock. Yes its a 7mm thread at 1mm pitch. A few people seem to have 6 and 8mm, but not 7. I could potentially get one ordered in for an undisclosed sum of money (I find out how it costs when they get it - and with such an oddball size I prefer to know whats it going to cost me before ordering).

Does anyone have a 7mm set or know of anyone or a shop who has one? Preferably in Canterbury/Chch - I don't plan on sending the engine block all around the country.

Or a handy suggestion on how to fix the problem with some alternative method. (I'm not going to use #8 fencing wire though!)

[Warr]

I seem to have a problem. One of the threads has been stripped from a head bolt recess. I've tried several auto shops/engineering places and helicoil/re-coil suppliers and none of them have an M7 helicoil in stock. Yes its a 7mm thread at 1mm pitch. A few people seem to have 6 and 8mm, but not 7. I could potentially get one ordered in for an undisclosed sum of money (I find out how it costs when they get it - and with such an oddball size I prefer to know whats it going to cost me before ordering).

Does anyone have a 7mm set or know of anyone or a shop who has one? Preferably in Canterbury/Chch - I don't plan on sending the engine block all around the country.

Or a handy suggestion on how to fix the problem with some alternative method. (I'm not going to use #8 fencing wire though!)
Mm Well I know you have thought of it.. But you havent given a reason why you wont.
BUT can you just take it out to 8M and use a larger bolt ?

[imdying]

Try ringing either Paykels or George Henrys.

/edit: Or Saeco or South Island Bearings.

[NinjaNanna]

In Auckland at least I have found EDL Fasteners to be fantastic, give them a try, at the very least I would expect them to tell you how much it will cost prior to getting them in

Here's a link to the phone number of the Christchurch store

http://www.yellowpages.co.nz/Pages/Search/Results/0,2878,a6001_m0,00.html?category=&businessName=edl+fasteners&location=christchurch&findit.value.x=0&findit.value.y=0

Cheers

NN

[FlyingDutchMan]

Mm Well I know you have thought of it.. But you havent given a reason why you wont.
BUT can you just take it out to 8M and use a larger bolt ?

8M? no. 8mm? Tempting... but I rather not. If I was to get one, I would have to get a 70mm long bolt, that has a 14mm flange and a small enough head on it so that a socket no wider than 15mm can tighten/loosen it (at the bottom of 70mm deep recess between valve spring guides). Why did Honda have to make everything so bloody difficult to get to?

With an 8mm bolt will probably have to use insert as 7mm dia is too big to tap to 8mm - it should be around 6.75mm. Using a 8mm insert - I don't want to take too much meat off the engine block because it only has so much... an 8mm insert will have ~10mm outside thread which would reduce the meat around it down to 1.5-2mm. Not really desirable.

Pics of bolt and stripped hole (two pics on right):
http://www.kiwibiker.co.nz/forums/showthread.php?t=41537

[Motu]

I think you might have a bit of trouble finding a 7 mm Helicoil,that's not a common size.But head bolts are often odd numbers...7mm,9mm,11mm - so try an engine reconditioning shop,they will be repairing stripped blocks.

[Warr]

Thanks for the link to the troublesome bolt.
Sux big time for sure. Keep us posted on progress.
I know you arent this desperate ...Yet
But just thinking outside the square a bit more .....
Would it be possible to put in a stud. With washer and nut on top?
That way you could tap the block to whatever size will give good connection and have it stepped to 7mm so you dont have to drill anything.

Next option is to alloy weld the block and drill and tap to 7mm

[FlyingDutchMan]

Thanks for the link to the troublesome bolt.
Sux big time for sure. Keep us posted on progress.
I know you arent this desperate ...Yet
But just thinking outside the square a bit more .....
Would it be possible to put in a stud. With washer and nut on top?
That way you could tap the block to whatever size will give good connection and have it stepped to 7mm so you dont have to drill anything.

Next option is to alloy weld the block and drill and tap to 7mm

That idea had been mentioned to me buy Blacks Fasteners... But that will be an expensive route... the block will have to skimmed after doing that and thats and easy $70+ gone right there... and thats as long as nothing gets too warping from getting heated up by welding...

The stud idea however, could well work out. I could tap it out to 9mm easy enough, get a 9mm to 7mm stud made up, and then try and find a nut which fits in the hole...

Here are some pics to better explain the situation... yes thats a 8mm 12 pt Koken socket with a 1/4" extension in it. The extension twisted a lot before the most of the bolts came loose... between 45-60 degrees.

[Warr]

Yes to your reservations on the alloy welding scenario. mmm
How about an 10mm insert. That would give enough meat for the original stud to attach to.

But thinking back to the original delema... if you could just find a 7mm helicoil without breaking the bank. Were you going to do it yourself or get a shop to do it ?
Did you try EDL Fasteners as already suggested ??

[FlyingDutchMan]

George Henry has quoted me $84 + GST. I really don't like spending that sort of money on a tool I'm in all likely hood only going to use once, but at the moment its a lot better than any other option. I'm going to check at the machine shop here at work to see if they have any.

[FlyingDutchMan]

Well ordered yesterday afternoon, and they have in already. Pretty darn quick! So will be picking it up this afternoon.

[NinjaNanna]

Well ordered yesterday afternoon, and they have in already. Pretty darn quick! So will be picking it up this afternoon.


I presume that you ordered a recoil kit through George Henry? So are you going to tackle it yourself or take the kit and block to a workshop to have it done???

[FlyingDutchMan]

I presume that you ordered a recoil kit through George Henry? So are you going to tackle it yourself or take the kit and block to a workshop to have it done???

I'll do it myself - cheaper and its a good learning experience. Have used taps and dies in the past before so I should be right.

[FlyingDutchMan]

Well I've picked it up now... Pleasant surprise. George Henry only charged me $75.95 inc GST. Much better than the $94.50 they were quoting. I'll see if I get time tonight to stick it in. If not, I'll give it a shot tomorrow. I'll post up some before + after pics.

[FlyingDutchMan]

Well took a shot at it this morning. Had to go get a 9/32 drill bit to drill it out before tapping. I hate bloody imperial things!

Anyway pics:

#1 I duct taped every thing up to make swarf and crap wouldn't get into the cylinders.

#2 Then drilled it out - the drill bit actually pulled straight into the hole... must be something to do with following a thread (or what was left of it). Had to pull back a bit to make sure it wasn't going to go straight through the bottom.

#3 Then got out the tap from the kit. 1/2 turn forwards, 1/4 turn back etc... with grease. Should have taken note how deep the hole was before starting, so would know when I'd reached the bottom. Just had to feel for when it got harder.

#4 Tap out, nice wee hole. Huge problems getting the crap out. Use grease and put the tap in out several times. CRC etc... Theres still a little left in there, but more effort than its worth to get it out.

#5 Inserts in. Note for future reference - they have been designed to go in. Not come out... you can't reverse them out. Broke of the tang. Put in the next one. broke off the tang. All done! Had to use two as they're only 9mm or so and the thread area on the bolt is about 20mm. Trialled it with a bolt and it sits lower in the hole than the next bolt over so no clearance issues. Could turn it all the way in and out using only finger power. Success! Will have to wait for other bolt from Mr Honda before re-assembling the thing.

All in all, a damn easy process. Notes for future reference though:
1. Measure how deep the hole is before you start. Put limit thingie on drill bit before drilling hole.

2. Mark how high the hole should come on the tap before starting. Will ensure you don't go too far and strip the newly tapped thread.

[scumdog]

Good one, keep us all posted.

Gotta get that chainsaw-with-rabies machine going again eh?

[cromagnon]

I stripped the 7mm thread on a camshaft journal holder :facepalm:, I ended up getting it helicoiled at Motor Reconditioners http://www.motorreconditioners.co.nz on hills rd, christchurch after searching around half a dozen different places. Nobody had the 7mm helicoil and didnt want to do it myself due to the huge cost of getting it wrong. Got motor reconditioners to buy in a kit for me especially and install the helicoil for me, knowing that i would be paying for the kit plus installation. But ending up doing a cheaper deal which meant they kept the 7mm helicoil kit even though they would mostly likely never need to use it again which was pretty good of them. So if you need a 7mm helicoil they have the kit to do it for anyone that has the same problem in the future.

[marsheng]

If there is enough material, drill out and tap an M9 or M10 thread. Make a steel or aly M10 to M7 slug and loctite it in.
Cheers Wallace