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[lesask]

Hi, so got car on ramps and stands to replace exhaust. Now 3 bolts sheared off right inside the cat flanges. No way of getting them out. Its like they welded in, Ive tried everything. So to replace the cat pipes as well and replace all is a huge job. So Im scrapping my car. I see no other option. Anyone got any ideas?

[aaronjb]

Drill them out and replace them with through bolts.

[Kevin Wood]

Drill them out and replace them with through bolts.

Yep, only takes a few minutes per bolt and once it's done...

[Doctor Gollum]

Agreed makes fitting easier too

[tunnie]

Dropping down pipes on V6 is not too bad, give them a blast of plusgas before hand. Pull them out then free to attach them with ease rather than under the car 

[Migv6 le Frog Fan]

The flange bolts almost always snap off. A set of good quality dril lbits, then patiently drill them out on a slowish speed without exerting a lot of pressure on the drill.
A bit of a pain,but the only way to successfully complete the job.

[terry paget]

Oh dear. Drilling them out is not so easy, take your time, use new drill bits, begin small small holes which you can drill out larger. Others may have more advice. What you do not want to do is break off a drill bit in the remains of the old bolt; then you have a problem.

[lesask]

many thanks readers. ive ordered a centre punch, im going to flush the bolts with the cat end flanges and ive ordered a set of high tensile cobolt drill bits. i will attempt to drill out completely, im not bothered about saving the threads as i will then use through bolts when re doing, a lot easier and even if in years to come and the same job needs doing again then they could be hacksawed through. I was blooming proud of myself to get the car up completely and i got the whole lot off in about half an hour, now im stuck for days. still i think i could do this job and i never give up. Les

[aaronjb]

Good to see you're not scrapping her over this set back (I understand the temptation in the heat of the moment, though! I probably never should have sold mine either, but.. anyhoo!)

As was said, don't snap a drill bit off in the bolt or you'll really be cursing, but other than that it's straightforward enough.

When selecting drill sizes to step up through remember that you want the 'web' in the centre of the drill (the flat bit) to fit just inside the pilot hole you drilled (unless you bought expensive split-points, but I doubt that). Apologies if I'm teaching the proverbial grandma how to suck eggs

[terry paget]

On my Senators the exhaust was attached to the cat section with nuts and bolts through holes. On the Omegas there are threads in the cat section into which bolts are screwed. When the poor owner needs to change the exhaust he usually breaks off the bolts and has a problem. Why on earth did Vauxhall change to what seems to me an inferior system? Ease of original assembly?

[lesask]

many thanks readers, thanks to the man who said i shouldnt scrap it and the advice on drilling out, you lost me on split ends or something but hopefully I can do this. again, many thanks. I will update the forum as and when i manage it, or dont manage it. 

[biggriffin]

take down pipes off, drill out flanges, and re-postion pre-cat lamdas. no more problems 

[TheBoy]

When drilling out, be careful to get dead centre, and on the final drill, not go too big - there is not much metal, and easy to leave too weak. Been there, t-shirt in the cupboard.

[TheBoy]

that said, I do normally retap mine. Anal, I know.

And use proper exhaust bolts, and I coppaslip the thread.

[Andy B]

that said, I do normally retap mine. Anal, I know.

Not anal .... just correct  that's what I did when I did  mine

And use proper exhaust bolts, and I coppaslip the thread.

Is a 'proper' exhaust bolt stainless?