Stripped threads from block - headbolts!

[Baxter]

Had a bit of a scare the other day with a customers Westy..

Stripped head off due to bubbles and pressurising the cooling system, some bolts not massivly tight, one quite slack really, thought nothing of it, head was recent and presumed whoever fitted it didn't do the correct torquing sequence.
Sent it off for checking. Came back f**ked, so ordered a new one (not cheap) went to put it on, dropped head bolts in, finger thightened the lot.
 Went for 1st torque and one bolt would not tighten!

 :shock:

Head back off....

Threads from block stripped out on one hole!

Scarey biscuits, now what?!

Ended up using a helicoil, which I was a bit dubious of, didn't think it would be up to the job.
But, By Jove it seems to have done the trick, head on and has just been back for it's 500 mile retorque, as usual a little bit of settling but all went well.

Fingers crossed eh, hope it carries on working!

Was just a quick post to say if this happens to anyone else it's not the end of the world.

 

[tylernt]

That's encouraging. I have now heard of one failed helicoil and one success. I still think head studs would be a good choice if a helicoil is necessary... eliminates all that twisting force on the helicoil.

Thanks for the report!

[55mpg06]

Good to know. That has been the one bolt I have always feared stripping.  :shock:  Thanks for sharing the info.

[clbanman]

When used properly, the helicoil results in an as strong or stronger than original threaded hole.  http://www.emhart.com/products/helicoil.asp They also have a stud-lock type that is specifically designed for applications such as head bolts.
We have used some in applications requiring torques over 2000 lb-ft. with no problems.  Beats scrapping a $37,000 casting.

[jtanguay]

When used properly, the helicoil results in an as strong or stronger than original threaded hole.  http://www.emhart.com/products/helicoil.asp They also have a stud-lock type that is specifically designed for applications such as head bolts.
We have used some in applications requiring torques over 2000 lb-ft. with no problems.  Beats scrapping a $37,000 casting.

how does one attain 2000 lb-ft torque?  :shock:

[lyeinyoureye]

200lbs 10 feet away.  

[clbanman]

Well I'm over 200, so I don't need 10 full feet.  We used to do it manually so torque multipliers came in real handy.  Now we use hydraulic torque machines which makes it very easy.

[somolovitch3]

umm......

if i may point out.....

thats just one kilo at.....

294 meters.....

umm....

 :twisted:

[hillfolk'r]

When used properly, the helicoil results in an as strong or stronger than original threaded hole.  http://www.emhart.com/products/helicoil.asp They also have a stud-lock type that is specifically designed for applications such as head bolts.
We have used some in applications requiring torques over 2000 lb-ft. with no problems.  Beats scrapping a $37,000 casting.

how does one attain 2000 lb-ft torque?  :shock:

a bigass torque multiplier

i remember on  certain deutz engines  a certain crank bolt needing like 260 ft pounds,then another 3/4 turn or something crazy like that
i do remember "testing" with a 600ft pound torque wrench,and i still needed like  half of the turn required
  :wink:

[bigblockchev]

I agree that helicoils are better than the original threads if done correctly. They have a greater pullout strength due to the larger diameter of the actual  bearing surface of the thread which is the outer side. Also the helicoil wire is produced by rolling which gives a better finish to the internal surface of the thread than a cut thread. Also you can stack torque multipliers on top of each other to give an even greater force. Cheers Dan

[madmatt]

yeh ive used alot of helicoils most aircraft engines use them.