200tdi Exhaust Stud

I had a leaking manifold gasket on my disco 200tdi recently. I have previously replaced all of the studs with stainless versions so I was not worried things coming apart. On refitting however the two central exhaust studs just pulled out of the ali casting in the head rather than tightening down. It is currently fitted and running but obviously still has a slight manifold leak due to this not lightening down adequately. I know to repair I will need to remove the head but what are my options with this?
Is it going to be possible to get a machine shop to helicol, (or attempt to do this myself) or am I going to be needing a replacement head?

Helicoil you can diy, have a look on yoututbe for videos on how to, not scary all all, practice on a scrap piece of alloy, you will need square on acess for a drill bit to get into the hole, dont go nay deeper than existing hole! green loctite is seriously good gear.
I like stainless a lot but cannot see stainless studs being any good for that job? what hardness/strength is the studding you used?

As above ref helicoil.
I've used stainless bolts and nuts on mine with no issues.

Helicoil is easy DIY, you just need to make sure you have sufficient access to be able to drill dead straight

Flossie said:

As above ref helicoil.
I've used stainless bolts and nuts on mine with no issues.

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On the manifold studs?

lynall said:

On the manifold studs?

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Original steel studs I've left there with stainless lock nuts, the original bolts are now stainless steel. Got them on the turbo to manifold and turbo to downpipe too.
It's been that long since I did it, it's possible that some of the original studs wound out with the nuts rusted to them and I've replace that set up with bolts instead. I've got them everywhere and only had one bind up on me causing grief but I can't remember where that particular stainless bolt was.

Flossie said:

Original steel studs I've left there with stainless lock nuts, the original bolts are now stainless steel. Got them on the turbo to manifold and turbo to downpipe too.
It's been that long since I did it, it's possible that some of the original studs wound out with the nuts rusted to them and I've replace that set up with bolts instead. I've got them everywhere and only had one bind up on me causing grief but I can't remember where that particular stainless bolt was.

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I have found with stainless fixings grease/oil helps a lot to stop the galling, and do not use air/battery guns it does not end well!
Bolts instead of studs are not a good idea especially in aluminium.

lynall said:

I have found with stainless fixings grease/oil helps a lot to stop the galling, and do not use air/battery guns it does not end well!
Bolts instead of studs are not a good idea especially in aluminium.

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I agree but I kept finding the studs came out with the nuts even using studlock.
Manifolds 'shouldnt' have to be removed frequently that's why I did it.
I removed them around 4 times at least over 16yrs but never for manifold problems, head gaskets, turbo, starter motor replacements usually.

Flossie said:

I agree but I kept finding the studs came out with the nuts even using studlock.
Manifolds 'shouldnt' have to be removed frequently that's why I did it.
I removed them around 4 times at least over 16yrs but never for manifold problems, head gaskets, turbo, starter motor replacements usually.

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Def 90 starter motor great job, if you are a gynacologist!