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Sheared exhaust manifold studs/warped manifold


petrolhead63

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Doing the warped manifold at last seeing as its off road with corroded coolant pipe. All studs looked good.....but have now concluded one at least has sheared but not dropped out. It looks sheared in line with cylinder head face.

Has anyone had experience of extracting the remains, is it likely to be seized in making it a drill job? and hard to get at too.

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Assuming its a Td5 you're talking about?

I had a stud snap with about 5 mm above the face, I tried every method available to get it moving and it just kept breaking further down the thread, I ended up drilling it out by hand.

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Be very careful if you use an extractor.

I had the same problem at the beginning of the year. 2 studs had broken - both flush with the head.

I drilled both out to 4.5 or 5mm ( can't remember which) & 1 just unscrewed with absolutely no effort - fantastic !

2nd 1 didn't budge at all & I stupidly, tried a bit harder. The extractor went bang & I then I had a very hard broken chunk of extractor inside the stud.

I tried cobalt & tungsten carbide drills on the visible end of the extractor & only polished it. I eventually managed to use a specially modified dremel grinding bit to get the extractor out.

In the end I had to drill the hole large enough to pick the bits of stud thread out. I was really lucky I only damaged a small bit of thread & couls tighten a replacement stud in.

Afterwards I was told by someone who's done quite a few that the best way is to build up the broken end of the stud with a TIG welder until there's enough to weld a bolt onto. Then unscrew.

The stud extractor has the potential disadvantage that if too large it cancause the stud to expand & grip the thread in the head even tighter.

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well, no TIG and had started before reading the post. I tried an extractor but having snapped one in the past I realised it was not going to budge so gave up. I have now drilled right through the stud to 5mm from memory...had hoped to peel the remains away from the thread which has worked before but so far not happening. The hole of course has gone very slightly off centre.

Its getting a little worrying, I do have thread repairs so could overdrill if required and use an insert.

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The allen key will expand the remainder of the stud into the softish aluminium head & not help removal.

I ended up drilling out to possibly 6.5mm (core diameter of M8 thread).

I also was slightly off-centre, but probably only about 0.5mm.

I managed to pick the remsinder of the stud out & the threads were only slightly damaged over about 20 degrees of the circumference.

Screwing a new stud in proved it was strong enough, but plan B was to drill larger for a M8 helicoil insert or if no good for an oversize M10 stud

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Glad you got it sorted. I was certainly getting worried after the extractor broke on ours.

I was happy the problem stud was at the front of the head, rather than the 1 @ the back - which would have been much worse to get the drill or Dremel at !

The only positive for me was that I finally justified buying a Dremel - after years of wondering what people did with them - lol.

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Thanks for your concern...I find the dremel itself a nice little thing...but rarely use it, the tools are not up to anything but working on toys I feel......I used the demel this time to grind the stud carefully from inside the hole I drilled but of course the stone fell off the tool and I had to get that out the hole too then! haha

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