stripped threads after cylinder head torque.

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baldock
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stripped threads after cylinder head torque.

Beitrag von baldock »

I thought it was the end of the engine rebuild but I should have guessed something else would go wrong.

2 of the bolts have stripped the thread in the aluminum cylinder head and 1 in the barrel ffrom one of the long bolts.

I guess this has happened before to some of you?

Is the only option to helicoil them? M6x1 with 20mm long helicoil?


Is it best to replace all of them rather than risking another going after re-assembling (google said they are much stronger than before)?
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Gunnar_HH
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Re: stripped threads after cylinder head torque.

Beitrag von Gunnar_HH »

I know no cylinder head that exists without a thread repair. I have seen a great many.
That is normal.
Repairing is easy as long as the engine is out.
Use TimeSert, HeliCoil or Ensat. Any that are too weak need to be redone. After the repair, put the cylinder head cover on and test each screw to see if it can withstand 10-12Nm. Then liquid seal DIRKO HT and final assembly.
I attach a manual for Ensat. They are Ensat SD M6 sleeves designed for an M8*1mm tap.

Cheers Gunnar
Ensat_einsetzen.pdf
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

Is ensat the one you would recommend over the other 2?

do they make them 20mm long?
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Gunnar_HH
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Re: stripped threads after cylinder head torque.

Beitrag von Gunnar_HH »

I have the best and easiest results with Ensat. Other colleagues swear on TimeSert.
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

The XL threads are all 20mm deep on M6 (I think M6x1.0 standard???). Please correct me if I'm wrong.

Do yours come in this size?
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Gunnar_HH
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Re: stripped threads after cylinder head torque.

Beitrag von Gunnar_HH »

These parts are better, because they are thinner. Outer cut just M8*1mm
https://www.ebay.co.uk/itm/264629787683 ... Swx5dhMojh
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

are they identical to the ones you use Gunnar?

My threads are 20mm deep. Do they make them that long?

Should I be looking for M6x1.0 standard pitch (20mm long) with outside of M8 fine pitch?
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Gunnar_HH
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Re: stripped threads after cylinder head torque.

Beitrag von Gunnar_HH »

Yes, I am using the thin wall parts because of the ability of a later repair (if it wont work) and the design of the cylinder head, there is not on all edges/corners enough space for drilling.
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

and you only screw in the top 10mm, leaving the remaining 10mm below untouched?
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Gunnar_HH
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Re: stripped threads after cylinder head torque.

Beitrag von Gunnar_HH »

Yes.
A screw wears optimally when you screw it in 6 times or more.
There is no need for 20 turns.
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

Thanks once again Gunnar. I'm not sure if I could have got this far without your help :top:
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Re: stripped threads after cylinder head torque.

Beitrag von volkerxl »

I am using the same like Gunnar. Outside M8x1.
When i build my new engine with the New head i used them as well.
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baldock
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

Lengthy but interesting youtube test where helicoil came out on top over Timesert (not Ensat but they look similar).
It confirms that both are stronger than the original aluminium thread would have been.
Helicoil can also be purchased 18mm long (3D).
I would have thought that the new aluminium threads are what would break if the insert goes, so the more threads gripping onto the insert the better?
As the Ensat are expensive and not available in the UK, I am going to give the 18mm helicoil a go, but I do appreciate your help with the other options.

https://www.youtube.com/watch?v=LpDduCVUy6w
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Gunnar_HH
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Re: stripped threads after cylinder head torque.

Beitrag von Gunnar_HH »

Try HeliCoil, it is also a good option. If it doesn't work, or if the HeliCoil thread comes out with the next disassembly, you can always use Ensat or TimeSert.
All three types of bushings are much better than the original material (butter aluninium).

Best regards
Gunnar
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Re: stripped threads after cylinder head torque.

Beitrag von baldock »

one of the threads is beneath a dowel. Guess that might be harder.

Can I re-use the head gasket after removing the head to do the barrel thread?
I know the engine hasn't been run yet but I guess the gasket has been squashed?
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