Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: lesask on 06 February 2017, 14:16:55
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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?
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Drill them out and replace them with through bolts.
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Drill them out and replace them with through bolts.
Yep, only takes a few minutes per bolt and once it's done...
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Agreed :y makes fitting easier too :y
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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 :y
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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.
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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.
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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
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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 :)
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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?
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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. ;D
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take down pipes off, drill out flanges, and re-postion pre-cat lamdas. no more problems :y
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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.
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that said, I do normally retap mine. Anal, I know.
And use proper exhaust bolts, and I coppaslip the thread.
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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? ::) :y
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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? ::) :y
no their mild steel with copper nuts. even on a full stainless RR system.
mine are m8, mild steel, washers n nuts, flanges drilled with 8 drill and wiggled about, :y
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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? ::) :y
no their mild steel with copper nuts. even on a full stainless RR system.
mine are m8, mild steel, washers n nuts, flanges drilled with 8 drill and wiggled about, :y
Mine were stainless on a full stainless system with s/s washers ...... courtesy of the stores at my previous place of work :D ;)
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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? ::) :y
no their mild steel with copper nuts. even on a full stainless RR system.
mine are m8, mild steel, washers n nuts, flanges drilled with 8 drill and wiggled about, :y
Mine were stainless on a full stainless system with s/s washers ...... courtesy of the stores at my previous place of work :D ;)
stainless bolts actually cost no more than mild when bought in bulk, cheapest's places to buy stainless bolts is Aberdeen, GT Yarmouth, and Lancaster, due to the offshore industry. :y
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My solution is not to break them off in the first place. I achieve this by first heating the flange and bolt to red heat with a blow torch. I allow it to cool, spray with penetrating oil, then gingerly apply torque with a spanner. If it moves a bit, and it usually does, I spray with more oil and turn it back and forth a bit to work the oil into it. Then I undo it a bit more, more oil, more to and fro, until it turns freely. Then I fully unscrew it, discard the screw, and clean the thread with a tap or better a thread cleaner. I reassemble with a new screw and copper ease.
Having broken off many in the past, I find this exercise most satisfying, and have not broken one off since I adopted this technique. It helps having a pit.
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cobalt drills good choice. If they are a decent make they probably will be split points. BUT cobalt drill bits are very brittle - do not apply any sideways force whatsoever and very little downforce. it will be a much bigger pain if they snap off in the holes - you can't drill out a stuck cobalt drill bit.
I vaguely remember using an angle grinder with thin disc to cut the bolts first.