Exhaust manifold stud holes and water jackets.

[Foetoid]

Hey guys. I recently discovered when taking off my turbo manifold to replace with a tubular one, that three of the manifold stud holes were stuffed. I got a mate of mine who's done it plenty of times, to come out and helicoil them. One was great but the other two are off-axis, which of course isn't ideal. I could remove the helicoil but the hole itself was drilled off-axis.

So what happens now. I could get a professional to come out and maybe turn them in to M10 stud holes but i wanted to know if this would foul into any water jackets.

I read somewhere they used Locktite on a stud to secure it in, cut off the end flat, then just used that as a solid base for a new hole drilled correctly. Other have filled it up with aluminium weld etc.

There is a guy local to me who's renown locally for being able to fix any thread anywhere, my main concern was if he's forced to go up to M10 if that would foul anything else inside the head. I'm going to be getting him to come out anyway to helicoil the turbo oil feed line bolt hole from the top corner of the head as overtightening the banjo bolt has stripped out the thread from the softer aluminium.

Ideas? Thoughts? Advice?

Thanks guys!

 

[iceman69510]

Which locations? It is commonplace to replace the end two studs with M10 and I have never heard of anyone having issues. Mitsu changed to this later.

I used Timeserts in my head and those require drilling out to a larger diameter as well. I did not have any issue doing that. If they are not too far of axis you might try the timeserts, but accuracy with them will be key.

 

[tektic]

I used studs that were m10 on one side and m8 on the other. The can be purchased from a vw dealer as part of a timing belt kit for a golf but can be purchased separately for like $2.

 

[Foetoid]

It's the top one second from the right, and the bottom one also second from the right. I know the middle bottom one ends in an oil return pocket, i just wondered about those two spots. I know going from M8 to M10 is marginal but i know nothing about the internals of these things.

Maybe the water jackets don't actually run either side of the stud holes anyway, so going wider and not deeper would be all good?