Stuck exhaust studs

[MikeK]

Hi everyone,

Hope everyone is ok i havent visited the forum in a while.
I was changing my exhaust in my 1.9 z3, the middle part with the catalytic converter. It was broken inside and was rattling a lot.
I managed to break the studs because the nuts were practicaly welded from the rust and removed the manifold.
Using the 2 nut method i removed one stud, the other one i hammered it out after some heat.
Then i am stuck with the two in the picture. Been fighting them for more than a month now.
Today i cut them, drilled them and then all my bits and discs broke. I even tried cutting from the side but nothing.
I dont expect to get them out without cutting the manifold from the sides and even then i dont know how to clean them out of the hole.
I know people around here are 1000 times more experienced with things like that so if you have any advice please let me know i really appreciate it.

I was also thinking what if i dont use them, will the middle ones have enough pressure with the gasket to seal the gaps?

 

[BillyB]

They look in a right old state now ,have you thought about getting a manifold off one of our friendly breakers.

 

[MikeK]

They look in a right old state now ,have you thought about getting a manifold off one of our friendly breakers.

I am afraid that if I try to remove the manifold I will get 5 more broken studs and this time will be on the engine block and engine is rotated so will be hard to reach.
I am thinking of getting an electric chisel hammer drill and trying again.
I've spent almost 150£ on tools now manifold was 70£

 

[IainP]

Visit Toolstation Tom, their Cobalt drill bits make short work of those studs. Been there. The studs should be splined if they’re originals. Should hammer out, but I’d be loathe to try that in situ.
I welded stainless coach bolts into mine because I had the manifold off.

Ordinary bolts will work, if you can get flanged bolts you can file flats on them so they lock.
Iain
oh, the manifold flange bolts are M7, the nuts are copper coated, they should come off, if the do lock on they tend to take the whole stud out.

 

[MikeK]

Visit Toolstation Tom, their Cobalt drill bits make short work of those studs. Been there. The studs should be splined if they’re originals. Should hammer out, but I’d be loathe to try that in situ.
I welded stainless coach bolts into mine because I had the manifold off.
View attachment 205739
Ordinary bolts will work, if you can get flanged bolts you can file flats on them so they lock.

I tried those bits with my friends professional drill and it only got that far and still they're stuck in.
They are stock they look exactly like the first picture. I am going to try an electric hammer drill with the chisel. It's a bit risky while the manifold is on the engine but I don't see any other options. They should be ready to come out by now if pushed straight out with a power tool I think and hope.
I got stainless bolts and nuts. I will be monitoring them if they loosen I can add some threadlocker and tighten again. I don't have a welder so I am trying to avoid buying one for now.

Will probably do this tomorrow will post any updates!
Thanks!

 

[IainP]

The one I did get out without drilling took a fair pounding. As did the one unbroken one. The other two I pilot drilled, 4mm then stepped up to 6+8mm. One decent smack and they popped out easily.
I welded them simply because I have history trying to fix broken exhausts, always in the pouring rain, late at night, needing the car the next morning. Trying to hold the top bolt to stop it rotating whilst it’s stinking hot is not my idea of fun.

 

[MikeK]

The one I did get out without drilling took a fair pounding. As did the one unbroken one. The other two I pilot drilled, 4mm then stepped up to 6+8mm. One decent smack and they popped out easily.
I welded them simply because I have history trying to fix broken exhausts, always in the pouring rain, late at night, needing the car the next morning. Trying to hold the top bolt to stop it rotating whilst it’s stinking hot is not my idea of fun.

It's great to know that what I am doing has worked before! I have a 4-5mm hole in both bolts so a few hits may be enough.

 

[t-tony]

A split into the side of the stud is the best thing IF you don't have enough heat to heat the flange to cherry red, any less heat and you're liable to break the flange.

Tony.

 

[Andyboy]

The manifold studs won't break off in the head and will unwind with the nut. With the manifold off (40 mins work) you can drive the old studs out with the manifold in a bench vice.

I have never known heads/manifold studs snap on an M42 or M44.

 

[MikeK]

One of the studs has been removed!!!

I used an electric chisel drill I borrowed from a friend.
The other one still in it doesn't move with any hammer so I am going to make a cut on the side and see if anything changes.
While preparing the new exhaust I realized...

I got the wrong bracket
But it's weird it looks like the new one is the one e36s and z3s from 98 should have... The one I have and fits on my gearbox mount I found online listed for E46.... Maybe gearbox was changed?!

 

[MikeK]

Success!!!!!!!
Those things really didn't want to come out..

Thanks everyone!

 

[t-tony]

Success!!!!!!!
Those things really didn't want to come out..
View attachment 205859

Thanks everyone!
[/QUOTE]

Well done for persevering.

Tony.

 

[MikeK]

So all installed. With stainless bolts and nuts no leaks so far!
At the back I have a custom muffler it's two metal flanges not attached to the exhaust itself that you just tighten together with two bolts to attach the muffler to the middle section of the exhaust. There was no gasket before just some silicone like ring in between. Has anyone seen that before? It seems right enough and cant see anything escaping from that section...

 

[t-tony]

Usually it's graphite impregnated sealing ring. But if its not leaking, its good.

Tony.