Exhaust Manifold Problem

[TouringMatt]

This is a pisser, investigated the blowing on cold start-up, only to find that the two end studs on the exhaust manifold have been sheared off sometime in the cars life - hence the blowing.

Its a complete f'kin mess, esp as someone has put exhaust putty over the area to try and hide it.

Apart from the fact the bolts are a c*nt to get at - cant get a socket on them - one other looks seized and the head is rounded, another came out the head with nice bits of ally thread on it

I'm guessing my only option is to lift the head off complete and get a recon jobbie

Matt

[Davenotouring]

The head will need to come off to have the old studs drilled out and rethreaded...

This was a problem on my 2.0 engine, a couple of studs were missing and it was making a nasty noise!

You should be able to get a socket to them...

This is a common problem on the 6 pots

I know where there is a 325i head with both manifold and no snapped studs for a ton....

[Brianmoooore]

It's possible to drill out snapped studs and helicoil stripped stud holes without removing the head, if you can get the manifold off.
Whether it's easier than removing the head to do so, is another matter.
Use a nut splitter / hacksaw blade / grinder to remove any remaining nuts, rather than twist the stud off.

[TouringMatt]

I cant see how i'd get to em once/if i got the manifold off.

Not enough room to get a drill in - or do helicoils not work like that?

Im not 100% sure my heads ok anyway, i get lots of condensation even when warm - ran the engine with the expansion cap off and noticed a stream of small bubbles coming off the return pipe from the top of the radiator at fast idle

Cheers
Matt

[Turbo-Brown]

Yeah, to Helicoil a hole you drill the old hole out to stightly larger than the root of the old thread, then tap it again with an oversize tap.

Then you wind the helicoil insert in and lastly break the little tang off.

It's actually not a bad idea to helicoil all the studs if you've got the head off as the inserts spread the load of the studs making them less likely to pull out.

[Simon13]

i think standard they are 8mm thread, upgrading to 10 or 12mm makes it alot stronger and easier to do again if the need arises